This PDF file contains the front matter associated with SPIE Proceedings Volume 11977, including the Title Page, Copyright information, and Table of Contents.

Quantum dots were encapsulated in polymeric phospholipid micelles conjugated to multiple ligands of SARS-CoV-2 spike protein to form fluorescent biomimetic nanoparticles for SARS-CoV-2 (COVID-QDs). Phosphatidylethanolaminepolyethylene glycol (PE:PEG) was appended with bis(4-methylphenyl)sulfone to form PE:PEG:bis-sulfone and selfassembled into micelles around CdSe/CdS core/shell quantum dots via thin-film rehydration. The introduction of the bissulfone group the surface of the micelle-encapsulated quantum dots provides multiple sites for conjugation to his-tagged SARS-CoV-2 spike protein via a bisalkylation mechanism. Based on the eluted unconjugated fraction, we estimate that an average of seven spike proteins are conjugated per COVID-QD. We treated an in-vitro model system for the neurovascular unit (NVU) with these COVID-QD constructs to investigate the COVID-QDs, and by proxy SARS-CoV-2, may modulate the NVU leading to the COVID-19 associated neuropathophysiology.

N-heterocyclic carbenes (NHCs) have attracted tremendous attention over the past decade, as it is expected to form strong coordination to transition metal complexes and surfaces. Here, we investigate the interactions between colloidal gold nanoparticles (AuNPs), or luminescent quantum dots (QDs) and a multidentate NHC-based polymer ligand. The ligand design relies on the nucleophilic addition reaction between several NHC anchoring groups, short polyethylene glycol (PEG) blocks, and a polymer chain. We find that such NHC-decorated ligands rapidly coordinate onto both sets of nanocrystals, which is attributed to the inherent σ-donating nature (soft Lewis base) of NHC groups combined with the soft Lewis acidic character of nanocrystal surfaces. We combine NMR spectroscopy, fluorescence spectroscopy, high-resolution transmission electron microscopy and dynamic light scattering to characterize the NHCstabilized nanocrystals and gain insights into the nature of the binding interactions. In particular, we find that the newly coated nanocrystals exhibit long-term colloidal stability over a broad range of conditions with no sign of degradation or aggregation build up, while preserving their photophysical properties, for at least one year of storage.

Superferromagnetic iron oxide (SFMIOs) is a new paradigm for Magnetic Particle Imaging (MPI) as it approaches the ideal imaging agent characteristics of a steep, step-like magnetization curve. Other than the expected 10-fold SNR and spatial resolution improvements from the square-like hysteresis curve, we demonstrate other unique qualities of SFMIOs that enable robust "chemical-shift-like" color multiplexing to potentially enable a range of magnetic "dyes" that work for at-depth imaging. We also demonstrate the extremely high sensitivity of SFMIO signal to the proximity of SFMIOs to each other, and explain how this could potentially be used as a FRET-like nanoscale ruler.

Fluorescent probes are extensively used in oncology for diagnostic applications, particularly for intra-operative tumor delineation. However, one of the biggest challenges of fluorescent contrast agents is the need for high signal-to-noise ratio in order to overcome background autofluorescence and be able to identify the tumor from surrounding normal tissue. Here we present a novel core-shell nanoparticle contrast agent, based on perovskite quantum dots (PQDs), which are gaining popularity due to their high quantum yield (<90%), size tunability and the ability to alter the emission spectrum by changing the halide ion. However, the biological applications of perovskites are almost non-existent due to their vulnerability in aqueous environment, as they rapidly disintegrate, even in the presence of moisture. Our approach involves developing nanoparticles with hydrophobic matrix containing a high density of PQDs in its core. We explore the efficiency of different hydrophobic polymers including polystyrene, silica and poly(lactic-co-glycolic acid) in protecting the PQDs from water and compared their long term effectiveness, observed over a period of two months. The feasibility of utilizing these nanoparticles as contrast agents was tested on breast cancer cells. The small size of the nanoparticles, which is typically ~60-70 nm, facilitate their intake inside cells via receptor-mediated endocytosis, thereby selectively lighting up the cancer cells green. This method will open new applications of perovskite nanocrystals in biomedical imaging including tumor detection, both pre- and intra-operatively, as well as therapy monitoring by aiding in tracking of drugs/nanoparticles.

The performances of a porous silicon nanorods / gold nanoparticle combination for high sensitivity plasmonic sensing was assessed. First, an innovative synthesis technique was developed in a view to obtain porous silicon particles (nanorods due to their elongated shape) with homogeneous size and shape. The porous silicon nanorods were then spin coated on a glass substrate covered with gold nanoparticles. The combination of the high specific surface area porous silicon nanorods and the plasmonic effect of the Au nanoparticles was tested to form a highly sensitive ellipsometric sensing device. The porous silicon nanorods could be attached to both the plane Au surface and the Au nanoparticles with a specific spectral shift in the reflected polarized light.

Nano formulations of anti-cancer natural products have revolutionized anti-cancer therapy and its challenges such as short half-life, low therapeutic index, non-specificity, efficiency, and bioavailability. Chrysin (Chr), a dihydroxyflavone isolated from a marine fungus Chaetomium globosum, is a known anti-cancer natural product. However, its free use in clinical scenarios is disadvantaged due to poor water solubility, rapid metabolism, and non-specific toxicity. In this study, Chr-nanoparticles (NPs) were prepared by the emulsion-diffusion evaporation technique. The optimized formulation of Chr-NPs was characterized for zeta size, potential, polydispersity index, transmission electron microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR). Chr-NPs had an average zeta size of 217.93 ± 3.45 nm, and a zeta potential of -15.63 ± 3.9 mV. As seen under the TEM, Chr-NPs measured an average size of 98.55 ± 4.01 nm. The NPs demonstrated an initial burst followed by a sustained release behaviour. The anti-cancer effects of Chr-NPs were investigated in human cervical cancer cells (HeLa) and human embryonic kidney (HEK) cells. MTT and propidium iodide live/dead flow cytometry assays demonstrated an improved IC50 value over the free drug treatment. An interplay of apoptosis and autophagy cell death mechanisms in Chr-NP treated HeLa cells was observed by Acridine Orange and MDC staining, visualized by confocal microscopy. Chr-NPs induced structural changes in the HeLa cell surface proteins and lipids were studied by FTIR spectroscopy. Natural products are the largest source of drug discovery; this study can pave the way to improve their chemistry sustainably and explore the cell death mechanisms.