Adsorption Performance of Human-like Collagen by Alkali-modified Kapok Fiber: A Kinetic, Equilibrium, and Mechanistic Investigation

Collagen-based dressings achieve excellent repair of the skin during metical cosmetology, which has received a lot of attention recently. Although great progress has been made on using biomass fiber as dressing carrier, more research is required on developing novel biomass fibers because of the limitations of (i.e., high cost and complex processing) of existing materials. In this study, the adsorption behaviors of two human-like collagen were studied by examining the Kapok fiber that was modified using alkali consisting of various amounts of the mass fraction. Results show that the alkali-modified Kapok fiber surface becomes rough with vertically arranged grooves, and the cross-section depicts the hollow cavity structure. The composition analysis of alkali modified Kapok shows that alkali dissolves part of the hemicellulose and lignin. Additionally, the surface energy rises sharply and the water contact angle changed from hydrophobic to hydrophilic. The adsorption amount of raw Kapok fiber is around 0.6g/g, which accounts for only one twenty-first of the adsorption amount of alkali-treated Kapok (around 12.6g/g), while the equilibrium adsorption amount was not sensitive to alkali concentration. The kinetics of human-like collagen followed both Quasi first and Quasi second order kinetic model, implying that the adsorption process where characterized by both physisorption and chemisorption. Finally, characterization of the AKF-2 coupled with the studies based on the inter-particle diffusion model showed a three-step of human-like collagen diffusion consisting of surface diffusion, inter-fiber diffusion and fiber' hollow cavity diffusion. Our results demonstrate a perfect high absorption performance of Kapok fiber providing a potential for application of collagen-base dressings.

Simple bone cyst: Uncommon cyst of jaw

Simple bone cyst (SBC) of the jaws is uncommon, representing approximately 1% of all jaw cysts. It is often accidentally discovered on routine dental examination as it is asymptomatic in most of cases. In this report, we discuss a case of SBC in a 16 years old female who presented in our department for correction of her mal-aligned teeth. On routine x-ray for orthodontic treatment, a well defined, unilocular radiolucent area approximately 3x1cm in size with scalloped borders on the left body of mandible expanding from distal surface of 34 to distal surface of 37 was discovered. Surgical exploration was required for both diagnostic and definitive treatment. The operative finding was hollow cavity without any epithelial lining.

A highly sensitive and selective nanosensor for near-infrared potassium imaging

Potassium ion (K+) concentration fluctuates in various biological processes. A number of K+ probes have been developed to monitor such fluctuations through optical imaging. However, the currently available K+ probes are far from being sensitive enough in detecting physiological fluctuations in living animals. Furthermore, the monitoring of deep tissues is not applicable because of short-wavelength excitation prevailingly used so far. Here, we report a highly sensitive and selective nanosensor for near-infrared (NIR) K+ imaging in living cells and animals. The nanosensor is constructed by encapsulating upconversion nanoparticles (UCNPs) and a commercial K+ indicator in the hollow cavity of mesoporous silica nanoparticles, followed by coating a K+-selective filter membrane. The membrane adsorbs K+ from the medium and filters out interfering cations. The UCNPs convert NIR to ultraviolet light, which excites the K+ indicator, thus allowing the detection of the fluctuations of K+ concentration in cultured cells and intact mouse brains.

Reversible Mechanical Regulation and Splicing Ability of Alginate-Based Gel Based on Photo-Responsiveness of Molecular-Level Conformation

In this study, benefiting from the sensitive molecular conformation transversion in azobenzene, a new strategy for fabricating alginate gels with the abilities of splicing and photo-responsive mechanical adjustment is reported. Firstly, a 4,4’-azobis(benzoylhydrazide) (Azo-hydrazide) linker was used to crosslink alginate physically via the electrostatic interaction between hydrazide groups and carboxyl groups. It was then shaped and transferred in situ to a chemically crosslinked gel via 450 nm light irradiation. Under the irradiation, the molecular conformation change of azobenzene in the linker was able to form covalent bonds at the crosslinking points of the gels. Furthermore, the reversible conformation transformation of azobenzene was able to induce the increase and decrease of the storage modulus under irradiation with 365 nm light and 450 nm light, respectively, while also providing gel-like mechanical properties, depending upon the irradiation time and given wavelength. Meanwhile, the results also indicated that active groups could contribute to the splicing ability of the gel and construct a hollow cavity structure. It is believed that this work could provide a versatile strategy for preparing photo-responsive gels with reversibly tunable mechanical properties.