Preparation, characterization and application of rod-like chitin nanocrystal by using p-toluenesulfonic acid/choline chloride deep eutectic solvent as a hydrolytic media.

Chitin nanocrystal (ChiNC) was fabricated based on p-toluenesulfonic acid -choline chloride deep eutectic solvent treatment. The obtained ChiNC was about 12-44 nm in width and 206-399 nm in length. The crystalline structure and the functional groups of ChiNC were maintained during the preparation process. Moreover, porcine pancreas lipase (PPL) was successfully immobilized onto the ChiNC to form the immobilized PPL (PPL@ChiNC). The resulting PPL@ChiNC has enzyme loading and activity recovery of 35.6 mg/g and 82.5%, respectively. The thermal stability, pH and temperature adaptabilities of PPL@ChiNC was improved, comparing with free PPL. The demonstrated DES treatment process was efficient for ChiNC preparation and the as-prepared ChiNC exhibited great potentials in biocatalysis and biomedical field.

Polymeric effects on DNA condensation by cationic polymers observed by atomic force microscopy.

Compaction of DNA by condensing agents can provide insights into DNA assembly processes, which is keenly related to the essence of gene transfection and gene therapy in vivo. In this paper, the morphology of different cationic polymer/DNA complexes was studied by using atomic force microscopy (AFM), which is keen to the mechanism of DNA condensation induced by amine-based cationic block copolymers with poly(poly(ethylene glycol) methyl ether methacrylate). It is found that the structures and dimensions of condensing agent/DNA complexes are sensitively dependent on the condensing agents. The size of DNA aggregates can be affected appreciably by polymers rather than monomers. The amount of nitrogen elements per polymer unit, rather than the molecular weights of polymers, appears to be more effective on the dimension of the condensates. The impact of the copolymer chain structures on the DNA aggregates indicates an effective venue for regulating the dimensions and structures of the DNA condensates, which is beneficial for optimizing delivery systems for gene transfection.

NHS-ester functionalized poly(PEGMA) brushes on silicon surface for covalent protein immobilization.

Poly(PEGMA) homopolymer brushes were developed by atom transfer radical polymerization (ATRP) on the initiator-modified silicon surface (Si-initiator). Through covalent binding, protein immobilization on the poly(PEGMA) films was enabled by further NHS-ester functionalization of the poly(PEGMA) chain ends. The formation of polymer brushes was confirmed by assessing the surface composition (XPS) and morphology (atomic force microscopy (AFM), scanning electronic microscopy (SEM)) of the modified silicon wafer. The binding performance of the NHS-ester functionalized surfaces with two proteins horseradish peroxidase (HRP) and chicken immunoglobulin (IgG) was monitored by direct observation. These results suggest that this method which incorporates the properties of polymer brush onto the binding surfaces may be a good strategy suitable for covalent protein immobilization.