Properties of aqueous solutions of lentinan in the absence and presence of zwitterionic surfactants

Structure, stability, antioxidant activity, and controlled-release of selenium nanoparticles decorated with lichenan from Usnea longissima

Selenium nanoparticles (SeNPs) have attracted widespread attention, but the poor water dispersibility restricted their applications seriously. Herein, Usnea longissima lichenan decorated selenium nanoparticles (L-SeNPs) were constructed. The formation, morphology, particle size, stability, physicochemical characteristics, and stabilization mechanism of L-SeNPs were investigated via TEM, SEM, AFM, EDX, DLS, UV-Vis, FT-IR, XPS, and XRD. The results indicated that the L-SeNPs displayed orange-red, amorphous, zero-valent, and uniform spherical nanoparticles with an average diameter of 96 nm. Due to the formation of CO⋯Se bonds or the hydrogen bonding interaction (OH⋯Se) between SeNPs and lichenan, L-SeNPs exhibited better heating and storage stability, which kept stable for more than one month at 25 °C in an aqueous solution. The decoration of the SeNPs surface with lichenan endowed the L-SeNPs with superior antioxidant capability, and their free radicals scavenging ability exhibited in a dose-dependent manner. Furthermore, L-SeNPs showed excellent selenium controlled-release performance. In simulated gastric liquids, selenium release kinetics from L-SeNPs followed the Linear superimposition model, which was governed by the polymeric network retardation of macromolecular, while in simulated intestinal liquids, it was well fitted to the Korsmeyer-Peppas model and followed a Fickian mechanism controlled by diffusion.

Structural insights into β-1,3-glucan cleavage by a glycoside hydrolase family

The fundamental and assorted roles of β-1,3-glucans in nature are underpinned on diverse chemistry and molecular structures, demanding sophisticated and intricate enzymatic systems for their processing. In this work, the selectivity and modes of action of a glycoside hydrolase family active on β-1,3-glucans were systematically investigated combining sequence similarity network, phylogeny, X-ray crystallography, enzyme kinetics, mutagenesis and molecular dynamics. This family exhibits a minimalist and versatile (α/β)-barrel scaffold, which can harbor distinguishing exo or endo modes of action, including an ancillary-binding site for the anchoring of triple-helical β-1,3-glucans. The substrate binding occurs via a hydrophobic knuckle complementary to the canonical curved conformation of β-1,3-glucans or through a substrate conformational change imposed by the active-site topology of some fungal enzymes. Together, these findings expand our understanding of the enzymatic arsenal of bacteria and fungi for the breakdown and modification of β-1,3-glucans, which can be exploited for biotechnological applications.

Delivering Nucleic-Acid Based Nanomedicines on Biomaterial Scaffolds for Orthopedic Tissue Repair: Challenges, Progress and Future Perspectives

As well as acting to fill defects and allow for cell infiltration and proliferation in regenerative medicine, biomaterial scaffolds can also act as carriers for therapeutics, further enhancing their efficacy. Drug and protein delivery on scaffolds have shown potential, however, supraphysiological quantities of therapeutic are often released at the defect site, causing off-target side effects and cytotoxicity. Gene therapy involves the introduction of foreign genes into a cell in order to exert an effect; either replacing a missing gene or modulating expression of a protein. State of the art gene therapy also encompasses manipulation of the transcriptome by harnessing RNA interference (RNAi) therapy. The delivery of nucleic acid nanomedicines on biomaterial scaffolds - gene-activated scaffolds -has shown potential for use in a variety of tissue engineering applications, but as of yet, have not reached clinical use. The current state of the art in terms of biomaterial scaffolds and delivery vector materials for gene therapy is reviewed, and the limitations of current procedures discussed. Future directions in the clinical translation of gene-activated scaffolds are also considered, with a particular focus on bone and cartilage tissue regeneration.