Surface-modified polylactic acid nanospheres with chitosan for antibacterial activity of 1, 2-benzisothiazolin-3-one

Controlled release of magnesium ions from PLA microsphere-chitosan hydrogel complex for enhancing osteogenic and angiogenic activities in vitro

Magnesium ions (Mg2+) play an essential role in the metabolism and regeneration of bone tissue. Appropriate amounts of Mg2+ have been shown to promote osteogenic differentiation of bone-derived cells and angiogenesis of endothelial cells. However, the initial burst release of Mg2+ may compromise the osteogenic effect, so the controlled release of Mg2+ is the critical consideration of the magnesium-containing tissue-engineered bone materials. This study proposes a microsphere-hydrogel complex to enhance the sustained-release effect and prolong the release cycle of Mg2+. For the initial release of Mg2+, polylactic acid (PLA) microspheres containing MgO and MgCO3 were fabricated with uniform morphology. Further microspheres were incorporated into the chitosan-based hydrogel to form microsphere- hydrogel complex for extended release. The complex demonstrated effective sustained release of Mg2+ over a period exceeding 28 days. In vitro cell experiments, CS/PLA@MgO-MgCO3 significantly enhanced migration and osteogenic differentiation of MC3T3-E1. Meanwhile, it can facilitate the generation of blood vessels in HUVECs. In conclusion, the magnesium-loaded microsphere-hydrogel complex achieves excellent dual sustained-release properties with an extended-release cycle while enhancing vascularized osteogenic activity in vitro, showing promising prospects for clinical application in bone defect treatment.

Tannic Acid Interfacial Modification of Prochloraz Ethyl Cellulose Nanoparticles for Enhancing the Antimicrobial Effect and Biosafety of Fungicides

With the poorly soluble and intrinsically unstable feature, prochloraz (Pro) was confronted with lower bioavailability in the crop defense against fungal erosion. Therefore, it was a challenging project to explore the innovative antifungal compound delivery system for improving bioavailability. The superior adhesive fungicide formulation was supposed to be an efficient pathway to enhance transmembrane permeability and biological activity. According to abundant phenolic hydroxyl groups, tannic acid (TA) was an ideal modified adhesive biomaterial to improve interfacial interactions. The fundamental purpose of this research was focused on the synergistic mechanism of TA-interfacial-modified Pro-ethyl cellulose (EC) nanoparticles for improving bioavailability and biosafety. In the stability test, TA-modified Pro-EC nanoparticles had the capacity to reduce Pro initial release burst, extending a persistent validity and improving anti-photodegradation property. The toxicity index of Pro-EC and Pro-EC-TA was approximately 2.93-fold and 4.96-fold that of Pro technical against Fusarium graminearum (F. graminearum), respectively. Compared with nonmodified EC nanoparticles, TA-modified EC nanoparticles obtained eminent transmembrane permeability and superior adherence ability to F. graminearum, for hydroxyl and carboxyl groups of TA to enhance interaction with target cell membranes. The contents of cellular reactive oxygen species induced by Pro-EC and Pro-EC-TA nanoparticles were about 2.31 times and 3.00 times that of the control check (CK), respectively. Compared to the CK group, the membrane potential and ergosterol values of F. graminearum treated with Pro-EC-TA nanoparticles were drastically reduced by 74.91 and 56.20%, respectively. In the biosafety assay, the maximum half-lethal concentration value of the TA-modified Pro-EC nanoparticles indicated that the acute toxicity of the Pro-EC-TA nanoparticles to adult zebrafish was approximately 8.34-fold reduced compared to that of the Pro technical. These findings demonstrated that the successful interfacial modification of Pro-EC nanoparticles with TA was a highly efficient, environmentally safe, and promising alternative for sustainable agricultural application, thus making the fungicide formulation process more simplified, easier fabrication, and lower cost.

Polylactic acid microparticles in the range of μg/L reduce reproductive capacity by affecting the gonad development and the germline apoptosis in Caenorhabditis elegans

Polylactic acid (PLA) accounts for approximately 45% of the global market of biodegradable plastics. Using Caenorhabditis elegans as an animal model, we examined the effect of long-term exposure to PLA microplastic (MP) on reproductive capacity and the underlying mechanism. Brood size, number of fertilized eggs in uterus, and number of hatched eggs were significantly reduced by exposure to 10 and 100 μg/L PLA MP. Number of mitotic cells per gonad, area of gonad arm, and length of gonad arm were further significantly decreased by exposure to 10 and 100 μg/L PLA MP. In addition, exposure to 10 and 100 μg/L PLA MP enhanced germline apoptosis in the gonad. Accompanied with the enhancement in germline apoptosis, exposure to 10 and 100 μg/L PLA MP decreased expression of ced-9 and increased expressions of ced-3, ced-4, and egl-1. Moreover, the induction of germline apoptosis in PLA MP exposed nematodes was suppressed by RNAi of ced-3, ced-4, and egl-1, and strengthened by RNAi of ced-9. Meanwhile, we did not detect the obvious effect of leachate of 10 and 100 μg/L PLA MPs on reproductive capacity, gonad development, germline apoptosis, and expression of apoptosis related genes. Therefore, exposure to 10 and 100 μg/L PLA MPs potentially reduces the reproductive capacity by influencing the gonad development and enhancing the germline apoptosis in nematodes.

Chitosan nanoparticles efficiently enhance the dispersibility, stability and selective antibacterial activity of insoluble isoflavonoids

Natural isoflavonoids have attracted much attention in the treatment of oral bacterial infections and other diseases due to their excellent antibacterial activity and safety. However, their poor water solubility, instability and low bioavailability seriously limited the practical application. In this study, licoricidin-loaded chitosan nanoparticles (LC-CSNPs) were synthesized by self-assembly for improving the dispersion of licoricidin (LC) and strengthening antibacterial and anti-biofilm performance. Compared to free LC, the minimum inhibitory concentration of LC-CSNPs against Streptococcus mutans decreased >2-fold to 26 μg/mL, and LC-CSNPs could ablate 70 % biofilms at this concentration. The enhanced antibacterial activity was mainly attributed to the spontaneous surface adsorption of LC-CSNPs on cell membranes through electrostatic interactions. More valuably, LC-CSNPs had no inhibitory effect on the growth of probiotic. Mechanism study indicated that LC-CSNPs altered the transmembrane potential to cause bacterial cells in a hyperpolarized state, generating ROS to cause cells damage and eventually apoptosis. This work demonstrated that the chitosan-based nanoparticles have great potential in enhancing the dispersibility and antibacterial activity of insoluble isoflavonoids, offering a promising therapeutic strategy for oral infections.

Intelligent design of polymersomes for antibacterial and anticancer applications

Polymersomes (or polymer vesicles) have attracted much attention for biomedical applications in recent years because their lumen can be used for drug delivery and their coronas and membrane can be modified with a variety of functional groups. Thus, polymersomes are very suitable for improved antibacterial and anticancer therapy. This review mainly highlighted recent advances in the synthetic protocols and design principles of intelligent antibacterial and anticancer polymersomes. Antibacterial polymersomes are divided into three categories: polymersomes as antibiotic nanocarriers, intrinsically antibacterial polymersomes, and antibacterial polymersomes with supplementary means including photothermal and photodynamic therapy. Similarly, the anticancer polymersomes are divided into two categories: polymersomes-based delivery systems and anticancer polymersomes with supplementary means. In addition, the bilateral relationship between bacteria and cancer is addressed, since more and more evidences show that bacteria may cause cancer or promote cancer progression. Finally, prospective on next-generation antibacterial and anticancer polymersomes are discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Lipid-Based Structures.