X-ray-Based Spectroscopic Techniques for Characterization of Polymer Nanocomposite Materials at a Molecular Level

This review provides detailed fundamental principles of X-ray-based characterization methods, i.e., X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, and near-edge X-ray absorption fine structure, and the development of different techniques based on the principles to gain deeper understandings of chemical structures in polymeric materials. Qualitative and quantitative analyses enable obtaining chemical compositions including the relative and absolute concentrations of specific elements and chemical bonds near the surface of or deep inside the material of interest. More importantly, these techniques help us to access the interface of a polymer and a solid material at a molecular level in a polymer nanocomposite. The collective interpretation of all this information leads us to a better understanding of why specific material properties can be modulated in composite geometry. Finally, we will highlight the impacts of the use of these spectroscopic methods in recent advances in polymer nanocomposite materials for various nano- and bio-applications

Electrospinning/Electrospray of Ferrocene Containing Copolymers to Fabricate ROS-Responsive Particles and Fibers

We demonstrate an electrospray/electrospinning process to fabricate stimuli-responsive nanofibers or particles that can be utilized as stimuli-responsive drug-loaded materials. A series of random copolymers consisting of hydrophobic ferrocene monomers and hydrophilic carboxyl groups, namely poly(ferrocenylmethyl methacrylate-r-methacrylic acid) [poly(FMMA-r-MA)] with varied composition, was synthesized with free radical copolymerization. The morphologies of the resulting objects created by electrospray/electrospinning of the poly(FMMA-r-MA) solutions were effectively varied from particulate to fibrous structures by control of the composition, suggesting that the morphology of electrosprayed/electrospun copolymer objects was governed by its composition and hence, interaction with the solvent, highlighting the significance of the balance of hydrophilicity/hydrophobicity of the copolymer chain to the assembled structure. Resulting particles and nanofibers exhibited largely preserved responsiveness to reactive oxygen species (ROS) during the deposition process, opening up the potential to fabricate ROS-sensitive material with various desirable structures toward different applications

The effect of nanoparticle properties, detection method, delivery route and animal model on poly(lactic-co-glycolic) acid nanoparticles biodistribution in mice and rats

We demonstrate the impact of engineering molecular structures of poly(acrylamide) (PAAm) and poly(-isopropylacrylamide) (PNIPAm) hydrogel composites on several physical properties. The network structure was systematically varied by (i) the type and the concentration of difunctional cross-linkers and (ii) the type of native or chemically modified natural polymers, including sodium alginate, methacrylate/dopamine-incorporated porcine skin gelatin and fish skin gelatin, and thiol-incorporated lignosulfonate, which are attractive biopolymers generated in pulp and food industries because of their abundance, rich chemical functionalities, and environmental friendliness. First, we added cross-linking agents of varying lengths at different concentrations to assess how the cross-linking agent modulates the mechanical properties of acrylamide-based composites with alginate. After chemically modifying gelatins from fish or porcine skin with methacrylate and/or dopamine, the acrylamide-based composites were fabricated with the chemically modified gelatins and thiolated lignosulfonate to assess the stress-strain behavior. Furthermore, swelling ratios were measured with respect to temperature change. The mechanical properties were systematically modulated by the changes in the molecular structure, that is, the length of the chemical unit between two end alkene groups in the difunctional cross-linker and the types of the additive natural polymers. Overall, PAAm hydrogel composites exhibit a significant, negative correlation between toughness and the volume fraction of the swollen state and between strain at fracture and the volume fraction of the swollen state. In contrast, PNIPAm hydrogel composites showed positive, but only moderate correlations, which is attributed to the difference in the network polymer structure

Attenuating Fibrotic Markers of Patient-Derived Dermal Fibroblasts by Thiolated Lignin Composites

We report the use of phenolic functional groups of lignosulfonate to impart antioxidant properties and the cell binding domains of gelatin to enhance cell adhesion for poly(ethylene glycol) (PEG)-based scaffolds. Chemoselective thiol-ene chemistry was utilized to form composites with thiolated lignosulfonate (TLS) and methacrylated fish gelatin (fGelMA). Antioxidant properties of TLS were not altered after thiolation and the levels of antioxidation were comparable to those of -ascorbic acid. PEG-fGelMA-TLS composites significantly reduced the difference in , , , and genes between high-scarring and low-scarring hdFBs, providing the potential utility of TLS to attenuate fibrotic responses

Attenuating Fibrotic Markers of Patient-Derived Dermal Fibroblasts by Thiolated Lignin Composites

Engineering composite biomaterials requires the successful integration of multiple feed- stocks to formulate a final product for functional improvement. Here we engineered biomaterial scaffolds to attenuate the fibrotic phenotype exhibited by high scarring (HS) patient-derived der- mal fibroblasts (hdFBs) by valorizing lignosulfonate from waste feedstocks of lignin. We utilized phenolic functional groups of lignosulfonate to impart antioxidant properties and the cell binding domains of gelatin to enhance cell adhesion for poly(ethylene glycol)-based scaffolds. Highly ef- ficient chemoselective thiol-ene chemistry was utilized for the formation of composites with thio- lated lignosulfonate (TLS) and methacrylated fish gelatin (fGelMA) in the PEG(poly (ethylene gly- col))-diacrylate matrix. Antioxidant properties of lignosulfonate was not altered after thiolation and the levels of antioxidation were comparable to a well-known antioxidant, L-ascorbic acid, as evi- denced by DPPH (2,2-diphenyl-1-picrylhydrazyl) and TAC (Total Antioxidant Capacity) assays. Unlike porcine gelatin, fGelMA remained liquid at room temperature and exhibited low viscosities, resulting in no issues of miscibility when mixed with PEG. PEG-fGelMA-TLS composites signifi- cantly reduced the differential of five different fibrotic markers (COL1A1, ACTA2, TGFB1 and HIF1A) between HS and low scarring (LS) hdFBs, providing the potential utility of TLS in a bio- material scaffold to attenuate fibrotic responses. </div