AVS 72 Session BI-ThP: Biomaterial Interfaces Poster Session

Thiocyanate (SCN^-) is a weakly hydrated anion that can interact relatively strongly with lipid membranes compared to other anions in the Hofmeister series. To date, the specific mechanisms governing this processes remain poorly characterized. To shed light on ion-lipid membrane interactions, we introduced KSCN into the subphase below 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) monolayers. This saturated lipid was chosen because it remains in the fluid phase at room temperature. Both the two-dimensional pressure of the monolayer and the salt concentration were varied. SFG was used to follow vibrational signals associated with the interfacial water structure, the lipid headgroups, the ordering of the alkyl chains, as well as the SCN^- anions. Such data are vital for characterizing the system, but the concentration of interfacial ions is not directly quantifiable. As such, we also employed total reflection X-ray fluorescence which can monitor the interfacial concentration of both K⁺ and SCN^- concentrations. Details of these interactions as well as their implications for Hofmeister chemistry will be discussed.

The investigation of how drugs or toxins alter cell mechanics is gaining significant traction in biomedical science, driven by the dual objectives of elucidating their mechanisms of action and enhancing drug screening processes. In this study, Atomic Force Microscopy (AFM) was employed to examine and analyze the mechanical responses of cells exposed to the neurotoxin Vipoxin. This method enables the precise measurement of key mechanical parameters such as cell stiffness and viscoelasticity before and after toxin introduction in the cell culture. It was demonstrated that the cells' stiffness and viscosity decreased with increasing Vipoxin concentration. Additionally, Total Internal Reflection Fluorescence Microscopy (TIRFM) was utilized to monitor morphological changes in the cells over time. These morphological changes were quantitatively analyzed using fractal analysis of the acquired images. The observed changes in cell shapes implied the reorganization of the cell cytoskeleton, thus providing insight into the cell mechanics under the influence of Vipoxin.

The efficient intracellular delivery of nucleic acids remains limited by the lack of vectors that are both effective and biocompatible. In this study, we synthesized silver nanoparticles, that were surface-engineered using low-pressure pulsed RF plasma polymerization with acrylic acid in vapor phase to introduce carboxylic functionalities, followed by covalent coupling to chitosan oligosaccharide (COS) through EDC chemistry, yielding metallo-polymeric nanocarriers (MPNCs). Surface functionalization characterization confirmed successful functionalization: FTIR and XPS evidenced carboxylation and amide bond formation, while DLS showed an increase in hydrodynamic size from AgNPs to AgNPs/COOH (166.3±23.04 nm) and then to MPNCs with attached DNA (276.0±17.75 nm). Zeta potential shifted from negative values for AgNPs (-13.4±1.39 mV) to strongly positive values for MPNCs, supporting electrostatic complexation with plasmid DNA (27.0±1.1 mV). Gel retardation assays demonstrated stable nanoplex formation at a plasmid:MPNC ratio of 1:6, and the complexes remained stable across a broad pH range. Importantly, the MPNCs protected plasmid DNA against both DNase I degradation and sequence-specific restriction digestion. Cell viability assay demonstrated that the COS used to encapsulate the modified nanosilver using EDC (92.05±9.46% and 102.79±2.85%), was substantially less cytotoxic than bare AgNPs (0% and 0%), and AgNPs/COOH (0% and 0%) equivalent to Triton X-100 (positive control); MPNCs at 0.5 mg/ml (87.06±3.98% and 93.55±1.65%) maintained high viability in A549 and HeLa cells respectively. Cellular uptake studies (in-vitro) further showed that MPNC-bound plasmid-DNA was internalized efficiently, with GFP expression detected in A549 cells and quantified by flow cytometry, reaching about 10% transfection efficiency at 24 h. Overall, the work demonstrates that pulsed plasma surface functionalization, combined with COS conjugation, can transform silver nanoparticles into a stable, biocompatible, positively charged non-viral vector with meaningful gene delivery performance.

The clinical translation of gold nanoparticles (GNPs) in nanomedicine hinges on a mechanistic understanding of their pharmacokinetics (PK) at the nano–bio interface. Traditional ADME (Absorption, Distribution, Metabolism, Elimination) model is effective for small molecules and biodegradable polymers. But it fails to capture the unique behaviour of inorganic GNPs, which are non-biodegradable, and not subject to enzymatic metabolism. Also, the interactions of GNPs in-vivo are not random biochemical processes. This Perspective introduces the ADIE (Absorption, Distribution, Immune interaction, and Elimination) framework. Immune interaction replaces metabolism as the pivotal phase. The journey of GNPs in-vivo is governed by transport physics and interfacial energetics. Convection and diffusion dictate distribution of the GNPs. While the collision of the nanoparticles with blood biomolecules and protein corona (PC) formation is governed by stochastic Brownian motion. The PC dictates immune recognition through competitive adsorption and thermodynamic binding energies. Also, it determines opsonization and clearance pathways. The elimination of GNPs is mainly via renal elimination. This is governed by size-exclusion physics and stealth coating (surface chemistry) property of the inorganic nanoparticles. While hepatic sequestration results from immune recognition. ADIE model offers a predictive foundation for designing GNPs with optimized biodistribution and clearance. Also, it advances the rational development of nanomedicines by integrating principles of transport physics, interfacial thermodynamics, and immune interaction.