Biopolymers最新文献

The stability of α-crystallin, the major protein of the mammalian eye lens and a molecular chaperone, is one of the most crucial factors for its survival and function. The chaperone-like activity and stability of α-crystallin dramatically increased in the presence of Zn². Each subunit of α-crystallin could bind multiple zinc atoms through inter-subunit bridging and cause enhanced stability. Three histidines H104, H111, and H119 of recombinant human αB-crystallin (HSPB5) are found to be the Zn²⁺ binding residues. In this article, we did site-directed mutagenesis of six histidine residues and made five-point mutants and a double mutant of αB-crystallin. We studied the effect of zinc on the chaperone function, surface hydrophobicity, and stability of the histidine mutants. We removed the histidine tag from H18A and H101V mutants and studied the stability and chaperone function in the presence and absence of zinc. H83 and H111 mutations showed similar enhancement in chaperone function like WT in the presence of Zn²⁺. Point mutants having his tags showed similar stability enhancement, but point mutant H18A without his tag showed less enhancement in stability in the presence of zinc. This indicates the significance of the presence of his tags in the study of zinc binding interaction with recombinant human αB-crystallin.

The crosslinked porous corn starch was prepared by two steps: the native corn starch was hydrolyzed by α-amylase and glucoamylase, then the porous corn was crosslinked by sodium trimetaphosphate (STMP). The morphology and size of granules, spherulites, crystal type, molecular structure, swelling properties, thermal stability and adsorption properties of the crosslinked porous starch were investigated. The results indicated that a lot of holes formed in the porous starch, and the particle size of starch granules decreased. Under the cross-linking action of STMP, the porous starch particles are cross-linked and agglomerated together. The crystalline form of porous starch presents A + V type, and crystallinity increased after crosslinking. The crosslinked porous starches have higher short-range ordering comparing to the porous without crosslinked porous starch. The crosslinking degree, melting enthalpy and melting peak of starch increased with the increase of STMP content. The bulk density and the vibrated density of the porous starch increased after crosslinking. With the increase of the content of STMP, the water and oil absorption of porous starch increased and then decreased. The MB adsorption capacity of crosslinked porous starch has the maximum value with the STMP 20 wt% content. MB adsorption behavior of porous starch is more consistent with the pseudo-second-order kinetic model, and the equilibrium adsorption increased after crosslinking.

We report the reversible redox-controlled DNA condensation using a simple dicationic diphenylalanine derivative which contains a disulfide unit as linker. Despite the conventional belief that DNA condensing agents require a charge of +3 or higher, this dicationic molecule functions below its critical aggregation concentration, representing a non-canonical DNA condensing agent. The interaction with DNA of the studied compound combines electrostatic effects with hydrophobic/stacking interactions provided with the diphenylalanine moiety. Upon reduction, the condensing agent is cleaved, weakening its interaction with DNA and resulting in DNA decondensation. Oxidation reverses this process, restoring the condensed state. This behavior was confirmed through ThT displacement, circular dichroism, ¹H NMR, and dynamic light scattering studies. Overall, this study introduces an innovative alternative for dynamic DNA manipulation applications.

In this paper, we offer a unique green synthetic approach for producing iron sulfide quantum dots (FeS₂ QD)-chitosan composites using gel chemistry. The technique uses the environmental features of chitosan, a biocompatible and biodegradable polysaccharide, and the excellent electrical properties of FeS₂ QDs. By sustainable chemistry principles, the synthesis process is carried out under gentle settings, using aqueous solutions and avoiding hazardous solvents and strong chemicals. The resulting FeS₂ QD-chitosan composite has superior structural integrity, homogeneous QD distribution, and improved physicochemical characteristics. Comprehensive characterization techniques, such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and photoluminescence spectroscopy, confirm the successful integration of FeS₂ QDs into the chitosan matrix while preserving their quantum properties. This work demonstrates the viability of gel chemistry as a green synthetic technique for generating functional nanocomposites, providing a scalable and environmentally responsible option for advanced material development.

When the kidneys are injured, uremic toxins (UTXs) accumulate in the body, affecting other tissues and causing a loss of essential body functions. This study investigated the adsorption of blood plasma-laden UTXs on the surface of PCL fibers to assess their potential as an alternative to membrane dialysis materials. Using plasma containing 26 UTXs at a concentration similar to that found in end-stage kidney disease patients, we analyzed the adsorbed proteins and examined clot formation in normal and toxin-treated plasma in the presence of PCL fibers. Our findings revealed that the presence of UTXs significantly increased the adsorption of proteins on PCL fiber meshes, without leading to increased clot formation. This suggests a lack of enzymatic activation despite the higher protein adsorption. Additionally, our study indicates that unmodified PCL surfaces have the potential to trigger a strong humoral immune response, underscoring the importance of understanding these interactions for the development of personalized treatment approaches for patients with kidney failure.

Exploring new ecological and simultaneous processes to modify wood fibers (WF) by-products is a required pathway toward circular economy and sustainability. Thus, plasma-activated water (PAW) and ultrasound (U) were employed as alternative methods to modify WF in a continuous process. Such treatments promoted the etching and cavities on the WF surface that destabilized the hydrogen bonds of the hemicellulose and lignin molecules, increasing the cellulose fraction. The addition of modified WF in the PLA matrix increased the storage modulus (2937 up to 5834) and Young modulus (3990 up to 6000 MPa), indicating well fiber/matrix interactions. The results corroborated that the use of modified WF as fillers could reduce the cost of extruded PLA-based composites and expand the production of bio-based materials for the mobility or packaging field.

Cryogels were fabricated by combining polyvinyl alcohol (PVA) and chitosan of varying molecular weights (Mw). In this study, the effects of chitosan Mw, types of boron-containing molecules on network formation, and boron release rate in resulted cryogels were investigated. The PVA/chitosan blend maintained a constant 4.5% (w/v) polymer content. PVA to chitosan weight ratio of 6:1 was maintained and fixed. Five percent w/w boric acid and borax (sodium tetraborate) crosslinkers were added in PVA and chitosan mixtures to construct cryogels. The freeze-dried specimens underwent crosslinking evaluation, chemical composition analysis by FTIR, and boron release studies by ICP-MS. The pore morphology and the swelling capacity of the cryogel have been assessed by SEM and incubation in water, respectively. Mechanical test was also used to evaluate the effect of borax and Mw of chitosan on cryogels' mechanical properties. It was demonstrated that the types of boron supply had a significant role on the cryogelation capability. For different chitosan Mw, the cryogels made using borax showed stable cryogels. In contrast, even after altering the chitosan Mw, the formula with boric acid was unable to create stable cryogels. In addition, boron release assay showed that the quantity of free boron in the incubation solutions decreased as the Mw of the chitosan component of the cryogel was reduced. Cell culture studies with MC3T3-E1 pre-osteoblast cells in the cryogels indicated that borax-crosslinked samples exhibited sustained cell viability. Alizarin red staining assay was used to study mineralization capacity of boron-containing hydrogels, which confirmed increase of mineralization in low molecular weight chitosan groups.

The antibacterial nanofibrous mat is crucial in biomedicine as it enhances infection control, expedites wound healing, and mitigates health hazards by decreasing antibiotic usage. A novel synergistic antibacterial and hydrophilic nanofibrous mat successfully fabricated by solution electrospinning from polyvinyl alcohol (PVA) incorporated Croton bonplandianum Baill (CBB) leaves extract. Antioxidant-enriched leaf extract of the CBB plant was integrated with PVA in varying proportions of 30% (CBB-30), 40% (CBB-40), and 50% (CBB-50) to manufacture antibacterial nanofibrous mat. The zone of inhibition (ZOI) was recorded at 16, 18, and 21 mm for CBB-30, CBB-40, and CBB-50, respectively. The wetted radius, a key parameter for moisture management properties, reached up to 20 mm for CBB-40 and CBB-50. This demonstrates the rapid absorption and quick-drying characteristics, highlighting the exceptional hydrophilicity of the nanofibrous mat. The increased dozing of CBB extract into the PVA also reduced its fiber diameter. The diameters of pure PVA, CBB-30, CBB-40, and CBB-50 were found as 396, 388, 279, and 241 nm, correspondingly. The developed nanofibrous mat, exhibiting ZOI of up to 21 mm, efficient moisture management properties, and a nanoscale fiber diameter of 241 nm, may possess significant uses in the biomedical domain.

Biomaterials with antimicrobial and muco-adhesive properties represent an efficient system for different applications. In this paper, a new biomaterial based on chitosan-camphor beads and their crosslinked form with glutaraldehyde was optimized. Low and high molecular weight chitosan were considered. After an optimization procedure of blank beads preparation, various strategies were used to load camphor into chitosan beads where eight different beads suspensions were characterized for their size and encapsulation efficiency of camphor. Powdered camphor was added to the chitosan solution during the beads preparation or to preformed beads while it was dissolving in water or in 2% acetic acid solution. Results showed that, camphor addition to chitosan solution led to the formation of homogeneous suspensions with reproducible and higher encapsulation efficiencies of camphor compared to the other formulations, irrespective of the chitosan weight. In addition, these beads were stable for 1 month of storage at 4°C. The camphor loaded cross-linked beads with glutaraldehyde (referred to as Cam-beads-GA) were more stable than noncross-linked beads (Cam-beads), which also demonstrated satisfactory stability results. Camphor embedding in chitosan beads was proven to occur through hydrogen bonding and potentially imine bonds by FTIR analysis. The optimized formulations constitute a suitable delivery system for other bioactive agents.