Molecular and Biocompatibility Characterization of Red Blood Cell Membrane Targeted and Cell-Penetrating-Peptide-Modified Polymeric Nanoparticles.

Red blood cells (RBCs) express a variety of immunomodulatory markers that enable the body to recognize them as self. We have shown that RBC membrane glycophorin A (GPA) receptor can mediate membrane attachment of protein therapeutics. A critical knowledge gap is whether attaching drug-encapsulated nanoparticles (NPs) to GPA and modification with cell-penetrating peptide (CPP) will impact binding, oxygenation, and the induction of cellular stress. The objective of this study was to formulate copolymer-based NPs containing model fluorescent-tagged bovine serum albumin (BSA) with GPA-specific targeting ligands such as ERY1 (ENPs), single-chain variable antibody (scFv TER-119, SNPs), and low-molecular-weight protamine-based CPP (LNPs) and to determine their biocompatibility using a variety of complementary high-throughput in vitro assays. Experiments were conducted by coincubating NPs with RBCs at body temperature, and biocompatibility was evaluated by Raman spectroscopy, hemolysis, complement lysis, and oxidative stress assays. Data suggested that LNPs effectively targeted RBCs, conferring 2-fold greater uptake in RBCs compared to ENPs and SNPs. Raman spectroscopy results indicated no adverse effect of NP attachment or internalization on the oxygenation status of RBCs. Cellular stress markers such as glutathione, malondialdehyde, and catalase were within normal limits, and complement-mediated lysis due to NPs was negligible in RBCs. Under the conditions tested, our data demonstrates that molecular targeting of the RBC membrane is a feasible translational strategy for improving drug pharmacokinetics and that the proposed high-throughput assays can prescreen diverse NPs for preclinical and clinical biocompatibility.

Charge-selective Raman scattering and fluorescence quenching by "nanometal on semiconductor" substrates.

Ag nanoparticles synthesized on n and p-type Si were shown to exhibit charge-selective surface-enhanced Raman scattering and fluorescence quenching. As revealed by electric force microscopy, the polarity and magnitude of the nanoparticle charge is controllable with the metal-semiconductor Fermi level difference and nanoparticle size. It is inferred that the Fermi level alignment is dominantly contributed by the charge-induced nanoparticle voltage. Nanoparticle charging also accounts for self-inhibition of coalescence during chemical reduction, allowing strong plasmon hybridization.

Thermoset-cross-linked lignocellulose: a moldable plant biomass.

The present work demonstrates a high biomass content (i.e., up to 90% by weight) and moldable material by controlled covalent cross-linking of lignocellulosic particles by a thermoset through epoxide-hydroxyl reactions. As an example for lignocellulosic biomass, Eastern redcedar was employed. Using scanning fluorescence microscopy and vibrational spectroscopy, macroscopic to molecular scale interactions of the thermoset with the lignocellulose have been revealed. Impregnation of the polymer resin into the biomass cellular network by capillary action as well as applied pressure results in a self-organizing structure in the form of thermoset microrods in a matrix of lignocellulose. We also infer permeation of the thermoset into the cell walls from the reaction of epoxides with the hydroxyls of the lignin. Compression tests reveal, at 30% thermoset content, thermoset-cross-linked lignocellulose has superior mechanical properties over a commercial wood plastic composite while comparable stiffness and strength to bulk epoxy and wood, respectively. The failure mechanism is understood to be crack propagation along the particle-thermoset interface and/or interparticle thermoset network.