Plasmonic nanoparticles have several applications ranging from catalysis to super-resolution imaging and information storage. Maximum density of optical states is confined on the nanoparticle surface, which are collectively excited by electromagnetic wave and are called surface plasmons. Using nanoparticle based plasmonic interaction with biological cells in an optical fiber integrated microfluidic chip, we show enhancement of fluorescence intensity. Signal from in situ imaging is analyzed with various controls to understand the mechanism. The present study is focused on nanoparticle interaction with cells and on optimization strategies to maximize the fluorescence enhancement at the vicinity of the nanoparticles, for important applications such as fluorescence-based biochip platforms. Result is also correlated ZnO nanoparticle effect on fluorescence enhancement, which has different optoelectronic properties compared to gold nanoparticles. Electromagnetic wave field model is employed to simulate the effect of gold and ZnO nanoparticle on cell with the assumption that the nanoparticles are a collection of discrete dipoles, which are ordered with the fluorescence molecules on cell wall. Simulation model shows enhancement of fluorescence intensity is occurred in presence of gold nanoparticles rather than ZnO nanoparticles, which is confirmed with experimental data.
Proc. SPIE. 9708, Photons Plus Ultrasound: Imaging and Sensing 2016
KEYWORDS: Oncology, Cancer, Tumors, Tissues, Nanoparticles, Chemical species, Molecules, Magnetism, Radiotherapy, Functional imaging, Finite element methods, Systems modeling, In vitro testing, Temperature metrology
Chemotherapy and radiation-therapy are conventional treatment procedure of cancer. Though radiation therapy is very common practice for cancer treatment, it has limitations including incomplete and non specific destruction. Heating characteristics of magnetic nanoparticle (MNP) is modelled using molecular dynamics simulation setup. This model would give an understanding for the treatment of cancer cell through MNP associated radiation-therapy. In this paper, alternating magnetic field driven heat generation of MNP is studied using classical molecular dynamics. Temperature is measured as an ensemble average of velocity of the atoms. Temperature stabilization is achieved. Under this simulation setting with certain parameters, 45°C temperature was obtained in our simulations. Simulation data would be helpful for experimental analysis to treat cancerous cell in presence of MNP under exposure to radiofrequency. The in vitro thermal characteristics of magnetite nanoparticles using magnetic coil of various frequencies (5, 7.5, 10 and 15 kHz), the saturation temperature was found at 0.5 mg/mL concentration. At frequency 50 kHz the live/dead and MTT assay was performed on magnetite nanoparticles using MC3T3 cells for 10 min duration. Low radio frequency (RF) radiation induced localized heat into the metallic nanoparticles which is clearly understood using the molecular dynamics simulation setup. Heating of nanoparticle trigger the killing of the tumor cells, acts as a local therapy, as it generates less side effects in comparison to other treatments like chemotherapy and radiation therapy.
The emission intensity of fluorophore molecule may change in presence of strong plasmon field induced by nanoparticles. The enhancement intensity is optimized through selective clustering or functionalization of nanoparticles in closed vicinity of fluorophore. Our study is aimed at understanding the enhancement mechanism of fluorescence intensity in presence of gold nanoparticles to utilize it in molecular sensing and in situ imaging in the microfluidic lab-on-chip device. Related phenomena are studied in situ in a microfluidic channel via fluorescence imaging. Detailed analysis is carried out to understand the possible mechanism of enhancement of fluorescence due to nanoparticles. In the present experimental study we show that SYTO9 fluorescence intensity increased in presence of Au nanoparticles of ~20 nm diameter. The fluorescence intensity is 20 time more compared to that in absence of Au nanoparticles. The enhancement of fluorescence intensity is attributed to the plasmonic resonance of Au nanoparticle at around the fluorescence emission wavelength. Underlying fundamental mechanism via dipole interaction model is explored for quantitative correlation of plasmonic enhancement properties.
Optofluidic schemes of inhibition, transport and activation by carrier molecules through cell membrane have interesting applications. Through plasmonic excitation of nanoparticles integrated in microfluidic channel, we observe cell membrane structural changes. Related phenomena are studied in situ in a microfluidic channel via fluorescence imaging. Detailed analysis is carried out to understand the possible application of this scheme in optically induced transport and expression of cell membrane protein. Optical properties of the cells undergoing plasmonic transport are monitored and correlated to cell expression assay. Plasmonic charge transport and optical transmission are measured in the microfluidic lab-on-chip along with in-situ imaging.
Detection of pathogens from infected biological samples through conventional process involves cell lysis and
purification. The main objective of this work is to minimize the time and sample loss, as well as to increase the
efficiency of detection of biomolecules. Electrical lysis of medical sample is performed in a closed microfluidic channel
in a single integrated platform where the downstream analysis of the sample is possible. The device functions involve,
in a sequence, flow of lysate from lysis chamber passed through a thermal denaturation counter where dsDNA is
denatured to ssDNA, which is controlled by heater unit. A functionalized binding chamber of ssDNA is prepared by
using ZnO nanorods as the matrix and functionalized with bifunctional carboxylic acid, 16-(2-pyridyldithiol)
hexadecanoic acid (PDHA) which is further attached to a linker molecule 1-ethyl-3-(3-dimethylaminopropyl) (EDC).
Linker moeity is then covalently bound to photoreactive protoporphyrin (PPP) molecule. The photolabile molecule
protoporphyrin interacts with -NH2 labeled single stranded DNA (ssDNA) which thus acts as a probe to detect
complimentary ssDNA from target organisms. Thereafter the bound DNA with protoporphyrin is exposed to an LED of
particular wavelength for a definite period of time and DNA was eluted and analyzed. UV/Vis spectroscopic analysis at
260/280 nm wavelength confirms the purity and peak at 260 nm is reconfirmed for the elution of target DNA.
Quantitative and qualitative data obtained from the current experiments show highly selective detection of biomolecule
such as DNA which have large number of future applications in Point-of-Care devices.