Layer-by-Layer Fabrication of PAH/PAMAM/Nano-CaCO3 Composite Films and Characterization for Enhanced Biocompatibility

Nanoparticle production and functionalization for various biomedical uses are still challenging. Polymer composites constituted of poly(amidoamine) (PAMAM), polyallylamine hydrochloride (PAH), and calcium carbonate (CaCO₃) nanoparticles have good biocompatibility with physiological tissue and fluids, making them excellent candidates for biomedical applications. This study investigated the characteristics of polymeric/nano-CaCO₃ composite films based on a PAH/PAMAM matrix, which were fabricated through layer-by-layer synthesis on quartz glass substrates. It was found that the as-prepared elastic moduli of the resultant (PAH/PAMAM)_n-CaCO₃ (where n represents the number of bilayers) composite films varied from 1.40 to 23.70 GPa for different degrees of cross-linking when 0.1 M nano-CaCO₃ particles were incorporated into the polymer matrix. The highly cross-linked (PAH/PAMAM)₁₅-CaCO₃ composite film had the highest recorded elastic modulus of 23.70 GPa, while it was observed that for all the composite films fabricated for the present study, the addition of the nano-CaCO₃ particles approximately doubled the elastic modulus regardless of the degree of polymerization. Live/Dead assays were used to determine whether the produced composite films were compatible with human lung fibroblast cells. The findings indicate that the (PAH/PAMAM)_7.5-CaCO₃ composite film had the most positive effect on cell growth and proliferation, with the (PAH/PAMAM)₁₅-CaCO₃ composite film demonstrating significant ion transport behavior with low impedance, which was considered good for in vivo rapid cell-to-cell communication. Therefore, the (PAH/PAMAM)_7.5-CaCO₃ and (PAH/PAMAM)₁₅-CaCO₃ composite films are potential tissue engineering biomaterials, but further studies are essential to generate more data to evaluate the suitability of these composites for this and other biomedical functions.

Virucidal Effect of the Mesoscopic Structure of CAC-717 on Severe Acute Respiratory Syndrome Coronavirus-2

Here, the virucidal effect of calcium bicarbonate with a mesoscopic structure (CAC-717) on severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was determined. Assays showed that CAC-717 had a strong virucidal effect on all examined SARS-CoV-2 isolates, including variant strains. The viral infectivity decreased within 15 s, and the virucidal activity of CAC-717 at a 1:49 ratio was similar to that of ethanol disinfectant. CAC-717 neutralization eliminated this virucidal effect, indicating that the alkaline condition of CAC-717 is important for virus inactivation and is an indicator of its mesoscopic structure and virucidal activity. The virucidal effect was observed in the presence of organic matter (bovine serum albumin). CAC-717 is a non-invasive and non-flammable substance with a low environmental burden, and its usefulness as a novel disinfectant has been confirmed.

Composite Porous Liquid for Recyclable Sequestration, Storage and In Situ Catalytic Conversion of Carbon Dioxide at Room Temperature

Permanent pores combined with fluidity renders flow processability to porous liquids otherwise not seen in porous solids. Although porous liquids have been utilized for sequestration of different gases and their separation, there is still a dearth of studies for deploying in situ chemical reactions to convert adsorbed gases into utility chemicals. Here, we show the design and development of a new type of solvent-less and hybrid (meso-)porous liquid composite, which, as demonstrated for the first time, can be used for in situ carbon mineralization of adsorbed CO₂ . The recyclable porous liquid composite comprising polymer-surfactant modified hollow silica nanorods and carbonic anhydrase enzyme not only sequesters (5.5 cm³  g^-1 at 273 K and 1 atm) and stores CO₂ but is also capable of driving an in situ enzymatic reaction for hydration of CO₂ to HCO₃ ^- ion, subsequently converting it to CaCO₃ due to reaction with pre-dissolved Ca²⁺ . Light and electron microscopy combined with X-ray diffraction reveals the nucleation and growth of calcite and aragonite crystals. Moreover, the liquid-like property of the porous composite material can be harnessed by executing the same reaction via diffusion of complimentary Ca²⁺ and HCO₃ ^- ions through different compartments separated by an interfacial channel. These studies provide a proof of concept of deploying chemical reactions within porous liquids for developing utility chemical from adsorbed molecules.