Biopolymers最新文献

An obstacle to the commercial application of polyhydroxyalkanoates (PHAs) and a co-product exopolysaccharide, alginate, is their high production cost. In this study, waste cooking oil (WCO) was used as an inexpensive carbon source for biopolymer production by Pseudomonas mendocina PSU. The highest biomass of 4.60 ± 0.06 g/L and PHA concentration of 2.58 ± 0.03 g/L (accounting for about 54% DCW) were achieved with a productivity of 0.072 g/L/h under optimal conditions determined by response surface methodology. Additionally, a maximum alginate yield of 8.85 ± 0.24 g/L was obtained as the co-product. The WCO, which primarily contained oleic acid (C18:1), palmitic acid (C16:0), and linoleic acid (C18:2) influenced the monomer composition of the produced PHA. The results demonstrated the presence of both SCL-PHA monomers such as 3HB (3-hydroxybutyrate) and MCL-PHA monomers including 3HHx (3-hydroxyhexanoate), 3HO (3-hydroxyoctanoate), 3HD (3-hydroxydecanoate), and 3HDD (3-hydroxydodecanoate) in varying molar fractions. Moreover, an average molecular weight of approximately 10⁴ Da and a polydispersity index of 1.58 were determined in the produced PHA, consisting predominantly of 3HB (86 mol%) when the cells were grown in 2.0% (v/v) WCO. Furthermore, the melting temperature (T_m) and glass transition temperature (T_g) were around 157°C and −20°C, respectively. Additionally, the produced alginate from P. mendocina PSU exhibited functional acetyl groups, which are a distinguishing feature of bacterial alginate, and showed an apparent viscosity comparable to commercial alginate from brown seaweed. These biopolymer characteristics demonstrate strong potential for biomaterial applications, adding value to WCO and reducing overall production costs.

The development of novel treatment strategies for tuberculosis (TB), including its multidrug-resistant forms, remains a global health priority. Conventional first- and second-line anti-TB drugs are often incorporated into polymer-based delivery systems to improve efficacy and reduce side effects. Among biodegradable, non-toxic, and biocompatible polymers, human serum albumin (HSA) stands out as a highly promising drug carrier. In this study, isoniazid (INH)-loaded human serum albumin nanoparticles were synthesized via the reaction of HSA macromolecules with cysteine in the presence of urea. Key nanoparticles characteristics—including size, polydispersity, drug loading efficiency, and drug binding capacity—were systematically evaluated and optimized. The effects of various formulation parameters, such as solution pH and concentration of urea, cysteine, albumin, and isoniazid, were investigated. Conformational changes in the protein structure were assessed using spectrofluorometric analysis. Additionally, the physicochemical properties and in vitro drug release profiles of HSA-INH nanoparticles were characterized. The antimicrobial activity of the nanoparticles was tested against the wild-type Mycobacterium tuberculosis H37Rv strain at isoniazid concentrations of 5, 25, and 50 mg/mL. The minimum inhibitory concentration of isoniazid when delivered via HSA nanoparticles was also determined.

The latest-generation Poly(L-lactic acid) (PLLA) based fully bioresorbable stents (BRS) are facing a grave challenge due to their higher clinical risk of post-implantation. There is consensus that the strut thickness of BRS far exceeds that of metal stents; this is the main reason for the poor clinical outcomes. Therefore, overcoming the gap in mechanical properties between PLLA and metal, and effectively reducing the strut thickness of BRS without sacrificing mechanical properties, is a research priority. In this paper, the vital structural weakness of BRS causing the poor mechanical properties was discovered from the preparation process. We proposed the use of an elastomeric coating to alleviate the damage in weakness during deployment. Experiments and numerical simulations conducted on PLLA stents with and without poly(L-lactide-co-ε-caprolactone) (PLCL) coating have confirmed that they can reduce stress concentration during deployment. The composite stents exhibit higher radial supporting capability after deployment. Significantly, the radial strength of the 100 μm thin-strut stent increased by 31%, up to 1061.8 mmHg. Moreover, in vivo animal experiments conducted on rabbits show encouraging biocompatibility and effectiveness of the composite stents. Our work provided a pure thin-strut PLLA stent with superior mechanical properties and biocompatibility, which can become a reliable platform for future research and clinical applications of BRS.

Periodontitis is a bacterial infectious disease. Photodynamic therapy (PDT) offers high selectivity, drug-resistance-free treatment, and immune regulation. The second-generation porphyrin photosensitizer Ce6 excels in reactive oxygen species (ROS) production. However, periodontitis pathogens' negative charge limits Ce6's interaction with them. This study prepared a modified cationic cyclodextrin (sPAM) and encapsulated Ce6 in an aqueous medium to create a nano-photodynamic system (Ce6@sPAM), which was characterized. In vitro evaluations assessed Ce6@sPAM's photodynamic performance, safety, antibacterial properties, and effects on immunoregulation. TEM images revealed Ce6@sPAM's irregular spherical shape, with a size of 236 nm by DLS and a Zeta potential of +16.4 mV. Ce6@sPAM exhibits a notably brief light half-life of merely 13 min, facilitating its swift in vivo clearance. SOSG and DCFH-DA fluorescence experiments showed Ce6@sPAM had stronger ROS generation (p < 0.05) and better bacterial penetration (p > 0.05) than Ce6. Co-incubation with Ce6@sPAM reversed bacterial surface potential from negative to positive. Bio-safety tests confirmed its excellent biocompatibility. In antibacterial tests, sPAM showed antibacterial properties, and Ce6@sPAM had a stronger effect than Ce6 under light (p < 0.001). Ce6@sPAM also exhibited high macrophage killing rates (> 90%) without specificity (p > 0.05) and can induce M1 macrophages to M2 polarization. Ce6-loaded modified cyclodextrin nanoparticles hold great promise for synergistic PDT in periodontitis treatment, especially in early stages for optimal immunomodulation.

In this study, the effect of microwave (MW) treatment on obtaining barley microfibers and their effect on the chemical, structural, and viscoelastic properties of films based on starch (S) and polyvinyl alcohol (P) was inspected. SEM, FTIR, and TGA analysis revealed that MW treatment effectively achieves the defibrillation and the destabilization of hydrogen bonds of the hemicellulose and lignin molecules, resulting in the obtention of barley microfibers (BM). XPS analysis allowed identification of the oxidation and crosslinking mechanism of S, P, and S/P films containing BM during the extrusion process. PBM and SPBM films showed an increase in CC proportions linked to the crosslinking phenomena and promoted stronger OCO interactions, which increased the storage modulus from 195.5 to 380.8 MPa and from 78.0 to 134 MPa, respectively. Conversely, SBM showed lower interactions CC and high COH bonds that reduced the component adhesion. Thus, the matrix type and extrusion process determined the chemical interaction with BM, resulting in films with different rigidity that can be useful in different sustainable packaging solutions.

Bacterial biofilms are complex, multi-component structures consisting primarily of four key elements: polysaccharides, metal ions, proteins, and extracellular DNA. In our research, we specifically focus on the polysaccharide and metal ion components, which play a crucial role in determining the biofilm's mechanical properties. Polysaccharides provide the structural matrix, although metal ions, particularly divalent cations like calcium and cobalt, cross-link with the polysaccharides, thereby modulating the biofilm's rigidity and viscoelastic behavior. By introducing divalent cations into nanocellulose, we can replicate this natural cross-linking process, allowing us to finely tune the material's mechanical properties to more closely resemble those of bacterial biofilms. This approach not only enhances the accuracy of synthetic biofilm models over alginate hydrogels but also provides valuable insights into how biofilms maintain their structural integrity in various environments. Our findings indicate that nanocellulose exhibits mechanical properties closer to biofilms than alginate analogs, making it a suitable non-living control for biofilm studies. Furthermore, divalent nickel, followed by calcium and magnesium, demonstrate a closer mechanical mimicry to biofilms. In conclusion, this research shows the potential of nanocellulose as a versatile material for bacterial biofilm mimicry.