Traditional in vitro diagnostics requires specialized laboratories and costly instrumentation, both for the amplification of nucleic acid targets (usually achieved by PCR) and for the assay readout, often based on fluorescence. We are developing hybrid nanomaterials-based sensors for the rapid and low-cost diagnosis of various disease biomarkers, for applications in portable platforms for diagnostics at the point-of-care. To this aim, we exploited the size and distancedependent optical properties of gold nanoparticles (AuNPs) to achieve colorimetric detection. Moreover, in order to avoid the complexity of thermal cycles associated to traditional PCR, the design of our systems includes signal amplification schemes, achieved by the use of enzymes (nucleases, helicase) or DNAzymes. Focused on instrument-free and sensitive detection, we carefully combined the intrinsic sensitivity by multivalency of functionalized AuNPs with isothermal and non-stringent enzyme-aided reaction conditions, controlled AuNPs aggregates, universal reporters and magnetic microparticles, the latter used both as a substrate and as a means for the colorimetric detection. We obtained simple and robust assays for the sensitive (pM range or better) naked-eye detection of cancer or infectious diseases (HPV, HCV) biomarkers, requiring no instrumentation except for a simple heating plate. Finally, we are also developing non-medical applications of these bio-nanosensors, such as in the development of on-field rapid tests for the detection of pollutants and other food and water contaminants.
The interactions between biological systems and nanostructured materials are attracting great interest, due to the
possibility to open up novel concepts for the design of smart nano-biomaterials that actively play a functional biological
role. On the other hand, the assessment of the potential toxic effects arising from such interactions is gaining increasing
attention, and a new field known as nanotoxicology is strongly emerging. In this frame, we investigated the response of
human neurons to gold surfaces with different levels of nanoroughness, finding out that neurons are capable to sense and
actively respond to these nanotopography features. These nanostructured substrates were also investigated to explore the
impact of nanotopography on morphology and genomics of adherent bacteria. A multidisciplinary approach was
exploited to characterize bacteria-nanostructured surface interactions, observing that type-1 fimbriae disappear in
bacteria grown onto nanorough substrates. We also show how nanoparticles interact with biomolecules in culture media
and <i>in vitro</i> and <i>in vivo</i> biological systems, by investigating the toxic effects of a wide range of nanomaterials (AuNPs, QDs, SiO<sub>2</sub> NPs), demonstrating the key role of size, shape, and surface coating.
Knowledge of the molecular mechanisms underlying the interactions between nanomaterials and living systems is
fundamental for providing more effective products for nanomedicine and drug delivery. Controlling the response of
cells/bacteria (such as activation of inflammatory processes or apoptosis/necrosis in tumor cells or pathogenic bacteria)
by tuning specific properties of the nanomaterials is ultimately the challenging goal. Notably, this may also provide
crucial information in the assessment of any toxic risks induced by nanoparticles on humans. However, in studying the
nano-biointeractions, it is imperative to take into account the dynamic evolutions of nanoparticles in the biological
environments (in terms of protein corona formation, size and charge changes) in synergy with the dynamic events
occurring in cells, including signal transduction, metabolic processes, homeostasis and membrane trafficking. In this
context, we discuss the impact of analytical technologies, especially in the field of proteomics, which can provide major
insights into the processes affecting the NPs surface as well as the cells and bacteria functionalities. In particular, we
show that a precise control of the chemical-physical characteristics of the interacting nanoparticles or nanostructures may
impact the cells by inducing changes in the proteomic profiles with direct consequences on their viability.