This PDF file contains the front matter associated with SPIE Proceedings Volume 9722 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Nanoparticles (NPs) are attracting interest in nanomedicine due to their potential medical applications, ranging from optical biolabels and contrast agents for magnetic resonance imaging to carriers for drug and gene delivery for disease therapy.^[1] Rare earth (RE) based nanophosphors exhibit important advantages compared with other available luminescent materials, such as quantum dots and nanostructures functionalized with organic dyes, due to their lower toxicities, photostabilities, high thermal and chemical stabilities, high luminescence quantum yields, and sharp emission bands.^[2] Yttrium orthovanadate NPs doped with Eu³⁺ and Bi³⁺, functionalized with poly acryl acid (PAA), and excitable by near-ultraviolet light have been synthesized by homogeneous precipitation at 120 °C from solutions of rare earth precursors (yttrium acetylacetonate and europium nitrate), bismuth nitrate, sodium orthovanadate, and PAA, in an ethylene glycol/water mixture. Quasispheres with sizes from 93 to 51 nm were obtained. The as synthesized NPs were already functionalized with PAA. The NPs showed the typical red luminescence of Eu³⁺, which can be excited with near-UV light through an energy transfer from the vanadate anion. The presence of Bi³⁺ shifts the maximum of the broad excitation band from 280 nm to 342 nm. This excitation path is much more efficient than the direct excitation of the Eu³⁺ electronic levels, and results in a much higher luminescence. The NPs can be uptaken by HeLa cells, and are eventually located in the lysosomes after being internalized. Finally, the functionalization with PAA provides -COOH anchors for adding functional ligands of biomedical interest that can be used for sensing applications.

We introduce a new set of amphiphilic polymers as multifunctional, metal-coordinating ligands adapted to surfacefunctionalize quantum dots (QDs), iron oxide nanoparticles (IONPs) and gold nanoparticles/nanorods (AuNPs/AuNRs). The ligand design relies on the introduction of several anchoring groups, hydrophilic moieties and reactive functionalities into a polymer chain, via one-step nucleophilic addition reaction. Such synthetic scheme also allows the insertion of target biomolecules during the ligand synthesis. This functionalization strategy yields nanocrystals that exhibit long-term colloidal stability over a broad range of biological conditions, such as pH changes and when mixed with growth media. When zwitterion groups are used as hydrophilic motifs, this provides compact nanocrystals that are compatible with conjugation to proteins via metal-polyhistidine self-assembly. In addition, we show that QDs ligated with these polymers can engage in energy or charge transfer interactions. Furthermore, nanocrystals coated with folic acid-modified polymers could promote the delivery of nanoparticle-conjugates into cancer cells via folate receptormediated endocytosis.

Colloidal semiconductor nanocrystals are ideal fluorophores for clinical diagnostics, therapeutics, and highly sensitive biochip applications due to their high photostability, size-tunable color of emission and flexible surface chemistry. The relatively recent development of core-seeded semiconductor nanorods showed that the presence of a rod-like shell can confer even more advantageous physicochemical properties than their spherical counterparts, such as large multi-photon absorption cross-sections and facet-specific chemistry that can be exploited to deposit secondary nanoparticles. It may be envisaged that these highly fluorescent nanorods can be integrated with large scale integrated (LSI) microfluidic systems that allow miniaturization and integration of multiple biochemical processes in a single device at the nanoliter scale, resulting in a highly sensitive and automated detection platform. In this talk, I will describe a LSI microfluidic device that integrates RNA extraction, reverse transcription to cDNA, amplification and target pull-down to detect histidine decarboxylase (HDC) gene directly from human white blood cells samples. When anisotropic colloidal semiconductor nanorods (NRs) were used as the fluorescent readout, the detection limit was found to be 0.4 ng of total RNA, which was much lower than that obtained using spherical quantum dots (QDs) or organic dyes. This was attributed to the large action cross-section of NRs and their high probability of target capture in a pull-down detection scheme. The combination of large scale integrated microfluidics with highly fluorescent semiconductor NRs may find widespread utility in point-of-care devices and multi-target diagnostics.

Pulsed laser ablation in liquid (PLAL) is nowadays gaining popularity as innovative, reliable and efficient technique to produce high-purity nanoparticles (NPs) of many inorganic and organic materials. In this context, attention has been recently focused on luminescent up-conversion NPs (UCNPs) which, being characterized by sharp emission bands in ultraviolet (UV)-to-near-infrared (NIR) range upon NIR irradiation, are in fact of great interest in many biological and biomedical applications. Moreover, with respect to organic dyes NPs and quantum dots, UCNPs show less toxicity, increased chemical stability, long-lifetime decays and lack of photo-bleaching. Our research focuses on generation of UCNPs of rare earth lanthanide-doped crystalline material, namely 18%Yb:1%Er:NAYF₄, by PLAL in water. It is well known that optical properties of NPs strongly depend on their features, as for instance size and shape, which in turn may be controlled by laser ablation parameters. Therefore, two different laser sources are used for the ablation processes in order to find the set of laser parameter, i.e. pulse duration, laser fluence and repetition rate, for which the luminescence of UPNPs is optimized: (i) Amplitude Satsuma HP3 system: 330 fs pulse duration, 1030 wavelength and (ii) Eolite Hegoa system: 50 ps pulse duration, 1030 nm wavelength. UCNPs are finally characterized by spectrophotometer analyses to define emission range and intensity under NIR light and by transmission electron microscopy (TEM) to determine their size and shape.

Complex metal nanoparticles offer a great playground for plasmonic nanoengineering, where it is possible to cover plasmon resonances from ultraviolet to near infrared by modifying the morphologies from solid nanocubes to nanoframes, multiwalled hollow nanoboxes or even nanotubes with hybrid (alternating solid and hollow) structures. We experimentally show that structural modifications, i.e. void size and final morphology, are the dominant determinants for the final plasmonic properties, while compositional variations allow us to get a fine tuning. EELS mappings of localized surface plasmon resonances (LSPRs) reveal an enhanced plasmon field inside the voids of hollow AuAg nanostructures along with a more homogeneous distributions of the plasmon fields around the nanostructures. With the present methodology and the appropriate samples we are able to compare the effects of hybridization at the nanoscale in hollow nanostructures. Boundary element method (BEM) simulations also reveal the effects of structural nanoengineering on plasmonic properties of hollow metal nanostructures. Possibility of tuning the LSPR properties of hollow metal nanostructures in a wide range of energy by modifying the void size/shell thickness is shown by BEM simulations, which reveals that void size is the dominant factor for tuning the LSPRs. As a proof of concept for enhanced plasmonic properties, we show effective label free sensing of bovine serum albumin (BSA) with some of our hollow nanostructures. In addition, the different plasmonic modes observed have also been studied and mapped in 3D.

Ligands made of lipoic acid (LA) appended with a polyethylene glycol (PEG) chain have been used in the aqueous phase growth of luminescent gold clusters with distinct emission from yellow to near-IR, using two different routes. In the first route, the gold-ligand complex was chemically reduced using sodium borohydride in alkaline medium, which gave near- IR luminescent gold clusters with maximum emission around 745 nm. In the second method, LA-PEG ligand was photochemically modified to a mixture of thiols, oligomers and oxygenated species under UV-irradiation, which was then used as both reducing agent and stabilizing ligand. By adjusting the pH, temperature, and time of the reaction, we were able to obtain clusters with two distinct emission properties. Refluxing the gold-ligand complex in alkaline medium in the presence of excess ligand gave yellow emission within the first two hours and the emission shifted to red after overnight reaction. Mass spectrometry and chemical assay were used to understand the photo-chemical transformation of Lipoic Acid (LA). Mass spectroscopic studies showed the photo-irradiated product contains thiols, oligomers (dimers, trimers and tetramers) as well as oxygenated species. The amount of thiol formed under different conditions of irradiation was estimated using Ellman’s assay.

Here, we reported a novel and facile thermal decomposited method to prepare NaMnF3 :Yb,Er/Tm upconversion nanoparticles (UCNPs). In this method, Rare earth acetate and manganese(II) 2,4-pentanedionato were used as raw material. The as-synthesized NaMnF3 :Yb,Er/Tm nanoparticles were monodispersed, uniform and their sizes were both smaller than 10 nm. The NaMnF3 :Yb,Er and NaMnF3 :Yb,Tm nanoparticles radiated intense pure red emission and near-infared emission under the excitation of 980 nm laser. Then, the core/shell structured NaMnF3 :Yb,Er/Tm@NaMnF3 nanoparticles were prepared to enhance the UC emission effectively.

Over recent years, gold nanorods (GNRs) have emerged as a promising material in biomedical optics and have been proposed as contrast agents for the photothermal therapy and the photoacoustic imaging of tumors. A pioneering approach to target tumors is the use of cellular vehicles, i.e. cells of the immune system that exhibit an innate tropism to tumors and that can be serve as Trojan horses. This strategy relies on cell types, such as tumor-associated macrophages or T cells, that are recruited by or naturally traffic to the microenvironment of tumors and that can be isolated from a patient and loaded with plasmonic particles in vitro. In this work, GNRs were synthesized and designed to combine high optical and photo-stability and the ability to accumulate into cells of the immuno system. Particles were silanized, PEGylated and conjugated with cationic moieties. Different cationic compounds were tested and the cell viability and uptake of the particles were studied on complementary cell types. The cytotoxicity test was based on a colorimetric WST-8 assay while the intracellular amount of gold and the optical absorbance of the cells were quantified by spectrophotometry. Moreover, we investigated the effect of GNRs on the cell migration and the production of cytokines in the presence of pro-inflammatory stimuli, which provide a functional overview on the feasibility of this approach to target.

The covalent integration of fluorescent and photoswitchable components within the same molecular skeleton can be exploited to activate fluorescence under optical control. Specifically, a photoswitchable oxazine heterocycle can be connected to either a coumarin or a borondipyrromethene fluorophore. Illumination of the resulting molecular dyads at an appropriate activation wavelength either opens the heterocycle reversibly or cleaves it irreversibly, depending on the relative positions of its methylene and nitro substituents. These photochemical transformations shift bathochromically the main absorption band of the fluorophore and allow its selective excitation at a given wavelength. These hydrophobic molecular dyads can be entrapped within the hydrophobic interior of self-assembling nanoparticles of amphiphilic polymer. The supramolecular envelope around the switchable compounds enables their transfer into aqueous environments and their operation under these conditions with minimal influence on their photochemical and photophysical properties. The reversible fluorescence activation, possible in one instance, imposes intermittence on the detected emission and offers the opportunity to resolve closely-spaced nanocarriers in time to reconstruct images with subdiffraction resolution. The irreversible fluorescence activation, possible in the other, maintains emission on after the activation event and permits the monitoring of the diffusion of the activated nanocarriers in real time with the sequential acquisition of images. Thus, these operating principles to solubilize and operate photoswitchable fluorophores in aqueous environments with the aid of supramolecular nanocarriers can lead to valuable protocols to image specimens with subdiffraction resolution and to monitor dynamic events noninvasively.

Plasmonic nanostructures serve as the main backbone of surface enhanced sensing methodologies, yet the associated optical losses lead to localized heating as well as quenching of molecules, complicating their use for enhancement of fluorescent emission. Additionally, conventional plasmonic materials are limited to operation in the visible part of the spectrum. We will elucidate how nanostructures consisting of conventional and polar dielectrics can be employed as a highly promising alternative platform. Dielectric nanostructures can sustain scattering resonances due to both electric and magnetic Mie modes. We have recently predicted high enhanced local electromagnetic field hot spots in dielectric nanoantenna dimers, with the hallmark of spot sizes comparable to those achievable with plasmonic antennas, but with lower optical losses. Here, we will present first experimental evidence for both fluorescence and Raman enhancement in dielectric nanoantennas, including a direct determination of localized heating, and compare to conventional Au dimer antennas. The second part of the talk will focus on the mid-infrared regime of the electromagnetic spectrum, outlining possibilities for surface enhanced infrared absorption spectroscopy based on polar and hyperbolic dielectrics.

Perhaps one of the most intriguing aspects of nanotechnology is the ability to create multimodal and multifunctional nanostructures that can open new venues in solving challenging biomedical problems. Here, we present multimodal magneto-plasmonic nanoparticles (MPNs) with a strong red-NIR absorbance, superparamagnetic properties and a high magnetic moment in an external magnetic field. Our design is based on self-assembly of 6 nm primary particles which consist of 5 nm diameter iron-oxide cores coated with a very thin ca. 0.5 nm gold shell. The assembly results in spherical highly uniform MPNs. We developed antibody targeted MPNs to address two highly challenging applications: (i) development of real-time assays for capture, enumeration and characterization of circulating tumor cells (CTCs), and (ii) enhancement of adoptive cell immunotherapy (ACT). Our results showed that MPNs can be used for simultaneous magnetic capture and photoacoustic (PA) detection of cancer cells in whole blood with no laborious processing steps. Furthermore, we demonstrated that MPNs conjugated with anti-CD8 antibodies, which are specific for cytotoxic T cells used in ATC, label CD8+ T cells with high specificity ex vivo and in vivo. Labeled T cells can be easily manipulated by a small magnet in suspension and under flow conditions. In addition, MPNs generate high contrast in MRI and PA imaging with the potential to detect just few cells per imaging voxel. These results show that immunotargeted MPNs can be explored for simultaneous visualization and magnetic guidance of T cell subsets in vivo for cancer treatment.

We characterize energy transfer between luminescent 1.5 nm diameter gold nanocrystal (AuNC) acceptors and three structurally/functionally-distinct classes of emissive donors including organic dyes, metal chelates and semiconductor quantum dots (QDs). Energy transfer efficiencies within the donor-AuNC assemblies were evaluated with steady-state and time-resolved measurements. Donor quenching was observed for every donor-acceptor pair although AuNC sensitization was only observed from metal-chelates and QDs. Results were analyzed with Förster’s dipole-dipole coupling model (FRET) and dipole-metal damping models including nanosurface energy transfer (NSET) and nanovolume energy transfer (NVET). FRET dramatically underestimated energy transfer efficiencies while the damping models provided qualitatively better fits to the data although neither fully reproduces the experimental data. Analysis suggests that organic dye donor quenching without corresponding AuNC sensitization results from enhanced intersystem crossing between dye singlet and triplet states driven by AuNC magnetic dipoles. We further consider factors that account for the unique electronic properties of the ultra-small luminescent AuNCs including the high excited state densities, rapid dephasing time and strong electron confinement as well as paramagnetic properties. Overall, the results provide insight into requirements necessary for realizing applications based on AuNC acceptor sensitization.

In this paper we present our recent studies on creating a nano-probe for the detection of all mRNA sequences in epithelial cells using nanoparticles coated with dye-labeled DNA strands. The nanoparticles are stable in biological conditions and they have the ability to enter the cells in high numbers.

The multivalent nature of commercial nanoparticle imaging agents and the difficulties associated with producing monovalent nanoparticles challenge their use in biology, where clustering of target biomolecules can perturb dynamics of biomolecular targets. Here, we report production and purification of monovalent gold and silver nanoparticles for their single molecule imaging application. We first synthesized DNA-conjugated 20 nm and 40 nm gold and silver nanoparticles via conventional metal-thiol chemistry, yielding nanoparticles with mixed valency. By employing an anion-exchange high performance liquid chromatography (AE-HPLC) method, we purified monovalent nanoparticles from the mixtures. To allow efficient peak-separation resolution while keeping the excellent colloidal stability of nanoparticles against harsh purification condition (e.g. high NaCl), we optimized surface properties of nanoparticles by modulating surface functional groups. We characterized the monovalent character of the purified nanoparticles by hybridizing two complementary conjugates, forming dimers. Finally, we demonstrate the use of the monovalent plasmonic nanoprobes as single molecule imaging probes by tracking single TrkA receptors diffusing on the cell membrane and compare to monovalent quantum dot probes.

Nanosensors employing quantum dots (QDs) and enzyme substrates with fluorescent moieties offer tremendous promise for disease surveillance/diagnostics and as high-throughput co-factor assays. Advantages of QDs over other nanoscaffolds include their small size and inherent photochemical properties such as size tunable fluorescence, ease in attaching functional moieties, and resistance to photobleaching. These properties make QDs excellent Förster Resonance Energy Transfer (FRET) donors; well-suited for rapid, optical measurement applications. We report enzyme sensors designed with a single FRET donor, the QD donor acting as a scaffold to multiple substrates or acceptors. The QD-sensor follows the concrete activity of the enzyme, as compared to the most common methodologies that quantify the enzyme amount or its mRNA precursor. As the sensor reports on the enzyme activity in real-time we can actively follow the kinetics of the enzyme. Though classic Michaelis-Menten (MM) parameters can be obtained to describe the activity. In the course of these experiments deviations, both decreasing and increasing the kinetics, from the common MM model were observed upon close examinations. From these observations additional experiments were undertaken to understand the varying mechanisms. Different enzymes can present different deviations depending on the chosen target, e.g. trypsin appears to present a positive hopping mechanism while collagenase demonstrates a QD caused reversible inhibition.

The nanometer-scale sensitivity of plasmon coupling allows the translation of minute morphological changes in nanostructures into macroscopic optical signals. In particular, single nanostructure scattering spectroscopy provides a direct estimation of interparticle distances in gold nanoparticle (AuNP) dimers linked by a short DNA double-strand [M. P. Busson et al, Nano Lett. 11, 5060 (2011)]. We demonstrate here that this spectroscopic information can be inferred from simple widefield measurements on a calibrated color camera [L. Lermusiaux et al, ACS Nano 9, 978 (2015)]. This allows us to analyze the influence of electrostatic and steric interparticle interactions on the morphology of DNA-templated AuNP groupings. Furthermore, polarization-resolved measurements on a color CCD provide a parallel imaging of AuNP dimer orientations. We apply this spectroscopic characterization to identify dimers featuring two different conformations of the same DNA template. In practice, the biomolecular scaffold contains a hairpin-loop that opens after hybridization to a specific DNA sequence and increases the interparticle distance [L. Lermusiaux et al, ACS Nano 6, 10992 (2012)]. These results open exciting perspectives for the parallel sensing of single specific DNA strands using plasmon rulers. We discuss the limits of this approach in terms of the physicochemical stability and reactivity of these nanostructures and demonstrate the importance of engineering the AuNP surface chemistry, in particular using amphiphilic ligands [L. Lermusiaux and S. Bidault, Small (2015), in press].

Conjugation of oligonucleotides or aptamers and their corresponding analytes onto plasmonic nanoparticles mediates the formation of nanoparticle assemblies: molecularly bound bundles of nanoparticles which cause a measurable change in the colloid’s optical properties. Here, we present further optimization of a “SERS off” competitive binding assay utilizing plasmonic and magnetic nanoparticles for the detection of the toxin bisphenol A (BPA). The assay involves 1) a ‘target’ silver nanoparticle functionalized with a Raman reporter dye and PEGylated BPA-binding DNA aptamers, and 2) a version of the toxin BPA, bisphenol A diglycidyl ether (BADGE), PEGylated and immobilized onto a silver coated magnetic ’probe’ nanoparticle. When mixed, these target and probe nanoparticles cluster into magnetic dimers and trimers and an enhancement in their SERS spectra is observed. Upon introduction of free BPA in its native form, target AgNPs are competitively freed; reversing the nanoparticle assembly and causing the SERS signal to “turn-off” and decrease in response to the competitive binding event. The assay particles were housed inside two types of optofluidic chips containing magnetically active nickel pads, in either a straight or spotted pattern, and both Fe₂O₃ and Fe₂CoO₄ were compared as magnetic cores for the silver coated probe nanoparticle. We found that the Ag@ Fe₂O₃ particles were, on average, more uniform in size and more stable than Ag@ Fe₂CoO₄, while the addition of cobalt significantly improved the collection time of particles within the magnetic chips. Using 3D Raman mapping, we found that the straight channel design with the Ag@ Fe₂O₃ particles provided the most uniform nanoparticle organization, while the spotted channel design with Ag@ Fe₂CoO₄ demonstrated a larger SERS enhancement, and thus a lower limit of detection.

Recently, plasmonic-based biosensing has experienced an unprecedented level of attention, with a particular focus on the nucleic acid detection, offering efficient solutions to engineer simple, fast, highly sensitive sensing platforms while overcoming important limitations of PCR and microarray techniques. In the broad field of plasmonics, surface-enhanced Raman scattering (SERS) spectroscopy has arisen as a powerful analytical tool for detection and structural characterization of biomolecules. Today applications of SERS to nucleic acid analysis largely rely on indirect strategies, which have been demonstrated very effective for pure sensing purposes but completely dismiss the exquisite structural information provided by the direct acquisition of the biomolecular vibrational fingerprint. Contrarily, direct label-free SERS of nucleic acid shows an outstanding potential in terms of chemical-specific information which, however, remained largely unexpressed mainly because of the inherent poor spectral reproducibility and/or limited sensitivity. To address these limitations, we developed a fast and affordable high-throughput screening direct SERS method for gaining detailed genomic information on nucleic acids (DNA and RNA) and for the characterization and quantitative recognition of DNA interactions with exogenous agents. The simple strategy relies on the electrostatic adhesion of DNA/RNA onto positively-charged silver colloids that promotes the nanoparticle aggregation into stable clusters yielding intense and reproducible SERS spectra at picogram level (i.e. the analysis can be performed without the necessity of amplification steps thus providing realistic direct information of the nucleic acid in its native state). We anticipate this method to gain a vast impact and set of applications in different fields, including medical diagnostics, genomic screening, drug discovery, forensic science and even molecular electronics.

Semiconductor quantum dots (QDs) serve as a valuable platform for understating the intricacies of nanoparticle cellular uptake and fate for the development of theranostics. Developing novel internalization peptides that maximize cellular uptake while minimizing the amount of peptide is important to allow space on the nanoparticle for other cargo (e.g. drugs). We have designed a range of branched, dendritic internalization peptides composed of polyarginine (Arg₉) branches (1 to 16 repeats) attached a dendritic wedge based on the sequence WP9G2H6. By attaching these branched dendritic peptides to QD’s, we can study the influence of branching on cellular uptake as a function of time, ratio, and degree of branching.

Recent interest in quantum dots (QDs) stems from the plethora of potential applications that arises from their tunable absorption and emission profiles, high absorption cross sections, resistance to photobleaching, functionalizable surfaces, and physical robustness. The emergent use of QDs in biological imaging exploits these and other intrinsic properties. For example, quantum confined Stark effect (QCSE), which describes changes in the photoluminescence (PL) of QDs driven by the application of an electric field, provides an inherent means of detecting changes in electric fields by monitoring QD emission and thus points to a ready mean of imaging membrane potential (and action potentials) in electrically active cells. Here we examine the changing PL of various QDs subjected to electric fields comparable to those found across a cellular membrane. By pairing static and timeresolved PL measurements, we attempt to understand the mechanism driving electric-field-induced PL quenching and ultimately conclude that ionization plays a substantial role in initiating PL changes in systems where QCSE has traditionally been credited. Expanding on these findings, we explore the rapidity of response of the QD PL to applied electric fields and demonstrate changes amply able to capture the millisecond timescale of cellular action potentials.

Gold nanoparticles (GNPs) can be used as a model NP system to improve the interface between nanotechnology and medicine since their size and surface properties can be tailored easily. GNPs are being used as radiation dose enhancers and as drug carriers in cancer research. Hence, it is important to know the optimum NP size for uptake not only at monolayer level but also at tissue level. Once GNPs leave tumor vasculature, they enter the tumor tissue. Success of any therapeutic technique using NPs depends on how well NPs penetrate the tumor tissue and reach individual tumor cells. In this work, multicellular layers (MCLs) were grown to model the post-vascular tumor environment. GNPs of 20 nm and 50 nm diameters were used to elucidate the effects of size on the GNP penetration and distribution dynamics. Larger NPs (50 nm) were better at monolayer level, but smaller NPs (20 nm) were at tissue level. The MCLs exhibited a much more extensive extracellular matrix (ECM) than monolayer cell cultures. This increased ECM created a barrier for NP transport and ECM was also dependent on the tumor cell lines. Smaller NPs penetrated better compared to larger NPs. Transport of NPs was better in MDA-MB231 vs MCF-7. This MCL model tissue structures are better tools to optimize NP transport through tissue before using them in animal models. Based on our study, we believe that smaller NPs are better for improved outcome in future cancer therapeutics.

The effect of 30nm Gold Nanoparticles (GNP) based on concentration and incubation time with respect to their cellular uptake kinetics was studied with Vero and HeLa cells . Photoirradiation effect of GNPs in combination with light emitting diode(LED) found to be remarkable and this work concentrates on optimizing concentration and light source. The effect of Gold nanoparticles alone and in combination with LED in malignant and normal cells lines were studied.

Dense inorganic nanoparticles have recently been identified as promising radiosensitizers. In addition to dose enhancement through increased attenuation of ionizing radiation relative to biological tissue, scintillating nanoparticles can transfer energy to coupled photosensitizers to amplify production of reactive oxygen species, as well as provide UVvisible emission for optical imaging. Lanthanum fluoride is a transparent material that is easily prepared as nanocrystals, and which can provide radioluminescence at a number of wavelengths through simple substitution of lanthanum ions with other luminescent lanthanides. We have prepared lanthanum fluoride nanoparticles doped with cerium, terbium, or both, that have good spectral overlap with chlorine6 or Rose Bengal photosensitizer molecules. We have also developed a strategy for stable conjugation of the photosensitizers to the nanoparticle surface, allowing for high energy transfer efficiencies on a per molecule basis. Additionally, we have succeeded in making our conjugates colloidally stable under physiological conditions. Here we present our latest results, using nanoparticles and nanoparticle-photosensitizer conjugates to demonstrate radiation dose enhancement in B16 melanoma cells. The effects of nanoparticle treatment prior to 250 kVp x-ray irradiation were investigated through clonogenic survival assays and cell cycle analysis. Using a custom apparatus, we have also observed scintillation of the nanoparticles and conjugates under the same conditions that the cell samples are irradiated.

Persistent luminescence nanoparticles have recently been proposed as innovative optical probes for small animal in vivo imaging. The main advantage of such probes is their ability to emit light for a long time after the end of their excitation, allowing in vivo imaging with low background. This work reports new information on the physico-chemical characterizations of Cr doped ZnGa₂O₄ nanoprobes in terms of synthetic procedure, luminescence properties as well as colloidal stabilities in different aqueous media and over the time.

Magnetic nanoparticles (MNPs) have been utilized in magnetic hyperthermia to treat solid tumors. Under an appropriate AC magnetic field, energy can be transferred to the MNPs to heat up the intended tissue target while sparing non-targeted healthy tissue. However, a sensitive monitoring technique for the dose of MNP thermal therapy is desirable in order to prevent over-treatment and collateral injury. Typical hyperthermia dosimetry often relies on changes in imaging properties or temperature measurements based on the thermal distribution. Alternative dosimetric indicators can include the biomechanical properties of the tissue, reflecting the changes due to protein denaturation, coagulation, and tissue dehydration during hyperthermia treatments. Tissue stiffness can be probed by elastography modalities including MRI, ultrasound imaging, and optical coherence elastography (OCE), with OCE showing the highest displacement sensitivity (tens of nanometers). Magnetomotive optical coherence elastography (MM-OCE) is one type of OCE that utilizes MNPs as internal force transducers to probe the tissue stiffness. Therefore, we examined the feasibility of evaluating the hyperthermia dose based on the elasticity changes revealed by MM-OCE. Superparamagnetic MNPs were applied to ex vivo tissue specimens for both magnetic hyperthermia and MM-OCE experiments, where temperature and elastic modulus were obtained. A correlation between temperature rise and measured stiffness was observed. In addition, we found that with repetitive sequential treatments, tissue stiffness increased, while temperature rise remained relatively constant. These results potentially suggest that MM-OCE could indicate the irreversible changes the tissue undergoes during thermal therapy, which supports the idea for MM-OCE-based hyperthermia dosage control in future applications.

SiC nanoparticles by carbothermal reduction show promising properties in terms of second harmonic and multiphoton excited luminescence. In particular, we estimate a nonlinear efficiency < d < = 17 pm/V, as obtained by Hyper Rayleigh Scattering. We also present results of cell labelling to demonstrate the potential use of SiC nanoparticles for nonlinear bioimaging by simultaneous detection of second harmonic and luminescence.

In addition to maintaining the structural integrity of the cell, the plasma membrane regulates multiple important cellular processes, such as endocytosis and trafficking, apoptotic pathways and drug transport. The modulation or tracking of such cellular processes by means of controlled delivery of drugs or imaging agents via nanoscale delivery systems is very attractive. Nanoparticle-mediated delivery systems that mediate long-term residence (e.g., days) and controlled release of the cargoes in the plasma membrane while simultaneously not interfering with regular cellular physiology would be ideal for this purpose. Our laboratory has developed a plasma membrane-targeted liquid crystal nanoparticle (LCNP) formulation that can be loaded with dyes or drugs which can be slowly released from the particle over time. Here we highlight the utility of these nanopreparations for membrane delivery and imaging.

Photodynamic therapy (PDT) is a clinically approved method for the treatment of cancer by using singlet oxygen, a highly reactive oxygen generated from a photosensitizer drug upon photoactivation. Limited light penetration depth into to the tissue means that PDT is unsuitable for deep tissue cancer treatments. This can be overcome by using X-ray /gamma rays activated nanoparticles able to trigger the photosensitizer drug and generate singlet oxygen. Additionally, inorganic nanoparticles interact more strongly with X and/or gamma rays than the tissue, allowing to concentrate the effects of radiation near nanoparticle surface and they can also be molecularly targeted to cancer cells. In this work we synthesized and characterized CeF3 nanoparticles, a well-known scintillator material. The nanoparticles were conjugated with Verteporfin, a photosensitizer drug by electrostatic interaction. We assessed the performance of CeF3 and the conjugates to generate singlet oxygen exposed to X-ray radiation. The X-ray singlet oxygen quantum yield of the nanoparticle-photosensitizer system was accurately quantified for the first time. This provided realistic estimates of the singlet oxygen dose taking into consideration the dose partition of the radiation between CeF3 and the tissue. Furthermore, we investigated gold nanoparticle-photosensitizer systems. We confirmed that pure gold nanoparticles itself generate singlet oxygen which is attributed to plasmonic effects. We found enhanced singlet oxygen generation from gold-Rose Bengal conjugates and gold nanorod–verteporfin conjugates. These singlet-oxygen-generating nanomaterials add a new dimension to radiation-assisted PDT.

The importance of microRNA (miRNA) dysregulation in the development and progression of diseases has made these short-length nucleic acids to next generation biomarkers. Tb-to-QD Förster resonance energy transfer (FRET) has several unique advantages over organic dye-based FRET systems for biomolecular sensing. Large Förster distances (6-11 nm) offer much high FRET efficiencies, exceptionally long Tb excited-state lifetimes (ms) enable time-gated detection void of autofluorecence background, and the narrow, symmetric, and tunable emission bands of QDs provide unrivaled potential for multiplexing. Here we report a rapid and homogeneous method to sensitively detect three different miRNAs (hsa-miR-20a-5p, hsa-miR-20b-5p, and hsa-miR-21-5p) from a single 150 µL sample based on multiplexed FRET between a luminescent Lumi4-Tb complex and three different QDs. The biosensing approach exploits both base pairing and stacking. Careful design and optimization of sequence lengths and orientations of the QD and Tb-DNA conjugates was performed to provide maximum selectivity and sensitivity for all three miRNA biomarkers. The assays work at room temperature and were designed for their application on a KRYPTOR diagnostic plate reader system.Only 30 min of sample incubation and 7.5 s of measurement are required to obtain ca. 1 nM (subpicomol) detection limits. We also demonstrate precise multiplexed measurements of these miRNAs at different and varying concentrations and the feasibility of adapting the technology to point-of-care testing (POCT) in buffer containing 10% serum. Our assay does not only demonstrate an important milestone for the integration of quantum dots to multiplexed clinical diagnostics but also a unique rapid miRNA detection technology that is complimentary to the rather complicated high-throughput and high-sensitivity approaches that are established today.

Hepatocarcinoma and esophageal squamous cell carcinomas threaten human life badly. It is a current issue to seek the effective natural remedy from plant to treat cancer due to the resistance of the advanced hepatocarcinoma and esophageal carcinoma to chemotherapy. Berberine (Ber), an isoquinoline derivative alkaloid, has a wide range of pharmacological properties and is considered to have anti-hepatocarcinoma and antiesophageal carcinoma effects. However its low oral bioavailability restricts its wide application. In this report, Ber loaded solid lipid nanoparticles (Ber-SLN) was prepared by hot melting and then high pressure homogenization technique. The in vitro anti-hepatocarcinoma and antiesophageal carcinoma effects of Ber-SLN relative to efficacy of bulk Ber were evaluated. The particle size and zeta potential of Ber-SLN were 154.3 ± 4.1 nm and −11.7 ± 1.8 mV, respectively. MTT assay showed that Ber-SLN effectively inhibited the proliferation of human HepG2 and Huh7 and EC9706 cells, and the corresponding IC₅₀ value was 10.6 μg/ml, 5.1 μg/ml, and 7.3 μg/ml (18.3μg/ml, 6.5μg/ml, and 12.4μg/ml μg/ml of bulk Ber solution), respectively. These results suggest that the delivery of Ber-SLN is a promising approach for treating tumors.

Timely detection of cardiac biomarkers is needed to diagnose acute myocardial infarction, implement the appropriate early treatment, and significantly reduce the chance of mortality. Ideally, for maximizing patient impact, a point of care device needs to be designed that is fast, sensitive, reliable, and small enough to be used in the ambulance and emergency department. Surface enhanced Raman spectroscopy (SERS) is a sensitive optical technique that can potentially be used to quantify the cardiac biomarkers of interest. In this work, silver nanoparticles were functionalized with a Raman reporter molecule and human cardiac Troponin I (cTnI) as an essential component of binding assays. Aggregated nanoparticles with the Raman reporter molecules were encapsulated in a silica shell to form SERS hotspots. Besides having a specific Raman spectra and binding affinity to cardiac Troponin I antibodies, the nanoparticles were designed to exhibit stability by using silica and polyethylene glycol (PEG) as part of the bioconjugation strategy. The specific narrow peaks from the Raman reporter molecule SERS signal allow for potential multiplexing capabilities as different Raman reporter molecules can be used in functionalized nanoparticles with different cardiac biomarkers. The SERS spectrum of the functionalized nanoparticles was measured to assess its potential to be used in an assay.

Complex biological samples such as serum contain thousands of proteins and other molecules spanning up to 13 orders of magnitude in concentration. Present measurement techniques do not permit the analysis of all pair-wise interactions between the components of such a complex mixture to a given target molecule. In this work we explore the use of nanoparticle tags which encode the identity of the molecule to obtain the statistical distribution of pair-wise interactions using their Localized Surface Plasmon Resonance (LSPR) signals. The nanoparticle tags are chosen such that the binding between two molecules conjugated to the respective nanoparticle tags can be recognized by the coupling of their LSPR signals. This numerical simulation is done by DDA to investigate this approach using a reduced system consisting of three nanoparticles (a gold ellipsoid with aspect ratio 2.5 and short axis 16 nm, and two silver ellipsoids with aspect ratios 3 and 2 and short axes 8 nm and 10 nm respectively) and the set of all possible dimers formed between them. Incident light was circularly polarized and all possible particle and dimer orientations were considered. We observed that minimum peak separation between two spectra is 5 nm while maximum is 184nm.

Cellular damage induced by free-radicals like reactive oxygen species has been implicated in several diseases. 2, 2-azobis(2-amidino-propane) dihydrochloride(AAPH) generates two potent ROS capable of inducing lipid peroxidation: alkoxy radical(RO-) and peroxy radical(ROO-). These radicals are similar to those that are physiologically active and thus might initiate a cascade of intracellular toxic events leading to oxidation, lipid peroxidation, DNA damage and subsequent cell death. Hence naturally anti-oxidant play a vital role in combating these conditions. In this study, resveratrol loaded nanostructured lipid carriers (Res-NLC) was prepared by hot melting and then high pressure homogenization technique. The effects of Res-NLC on free radical scavenging capacity and antioxidative damage is investigated. The particle size and zeta potential of Res-NLC were 139.3 ± 1.7 nm and −11.21 ± 0.41 mV, respectively. By free radical scavenging assays, the IC₅₀ value of Res-NLC were 19.25, 5.29 μg/mL with DPPH, ABTS assay respectively, and 0.161 mg ferrous sulfate/1 mg Res-NLC with FRAP assay; and by AAPH-induced oxidative injury cell model assay, Res-NLC showed the strong protective effect against the human liver tumor HepG2 cell oxidative stress damage. These results indicated that the antioxidant properties of Res-NLC hold great potential used as an alternative to more toxic synthetic antioxidants as an additive in food, cosmetic and pharmaceutical preparations for the oxidative diseases treatment.

ZnO is a well-known luminescent material that reacts with light to generate free radicals enabling its use in cancer treatment by Photodynamic Therapy (PDT). Unfortunately, up to know, the photo-excitation of ZnO-based materials’ requires excitation with ultraviolet light, which limits their biomedical applications. In this regard, this work investigates the effect of Ti species incorporation into the lattice of ZnO nanoparticles (NPs) with the aim of improving the corresponding optical properties and enabling the two-photoexcitation with 690nm-light (near infrared light). A modified polyol-based route was used to synthesize pure and Ti-doped (9% at.) ZnO NPs. X-ray diffraction confirmed the formation of ZnO-wurtzite whereas Scanning Electron Microscopy confirmed the formation of monodispersed 100-nm NPs. Raman Spectroscopy measurements evidenced the presence of zinc interstitials (Zni) and oxygen vacancies (VO) in the host oxide strcuture. Asynthesized NPs were excited using the technique of two-photon fluorescence microscopy (TPFM). The photoluminescence (PL) spectra generated from the analysis of TPFM images revealed a high emission peak presence in the green region (555 nm) that was assigned to VO. Also, a weak but noticeable band at 420 nm was detected, which is attributed to electron transition from the shallow donor level of Zni to the valence band. These PL transitions will favor triplet states formation necessary to yield cytotoxic reactive oxygen species. Furthermore, the presence of the PL peaks confirmed the Ti-ZnO NPs capacity to be excited by 690-nm light, thus, opening new possibilities for this NPs to be used in lightinduced bio-medical applications.