RESUMEN
Objective:To prepare Periplaneta americana thermosensitive hydrogel and investigate its effect on wound healing in diabetic rats. Method:Taking N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) as monomers, thermosensitive poly(NIPAM-co-AAc) [P(NIPAM-co-AAc)] polymeric material was prepared by free radical polymerization, then thermoresponsive copolymer P(NIPAM-co-AAc)-g-HA was synthesized by conjugating P(NIPAM-co-AAc) to hyaluronic acid (HA). The structure and lower critical solution temperature (LCST) of the graft copolymer were characterized by proton nuclear magnetic resonance spectroscopy (1H-NMR) and ultraviolet spectrophotometry (UV). P. americana thermosensitive hydrogel was prepared by dialysis method, and it was characterized by scanning electron microscope (SEM), rotation rheometer and thermogravimetric analyzer to observe section structure, rheological properties and thermal stability. Differential scanning calorimetry, X-ray diffraction and Fourier transform infrared spectroscopy were employed to identify the inclusion of P(NIPAM-co-AAc)-g-HA temperature sensitive material for P. americana extract, and to investigate the effect of P. americana thermosensitive hydrogel on wound healing in diabetic rats, and the rate of wound healing was calculated by Image-Pro Plus 6.0 software. Hematoxylin-eosin (HE) and Masson staining were used to observe the pathological changes of the wounds of rats in each group. Result:P(NIPAM-co-AAc)-g-HA temperature sensitive material was successfully synthesized, its LCST was between 29 ℃ and 31 ℃, it had a dense and uniform porous structure and could uniformly include P. americana extract. Pharmacodynamic studies showed that P. americana thermosensitive hydrogel group had the best effect on promoting wound healing, its infiltration degree of inflammatory cells was significantly reduced, collagen and fibroblasts arranged neatly and compactly, and the density of neovascularization was significantly increased by comparing with the model group. Conclusion:P. americana thermosensitive hydrogel can effectively promote wound healing of diabetic rats and overcome the shortage of marketed P. americana liquid preparations, this paper can provide a reference for the development of P. americana extract preparations to promote wound healing in diabetic patients.
RESUMEN
Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is an important analytical technique for biological macromolecules,such as proteins,peptides and nucleic acid, especially in the field of microbial identification. Based on previous study,a linear MALDI-TOF MS has been designed and assembled for biological applications. The instrument comprises a vacuum system,a vacuum fast sample introduction system, an optical system, a time-of-flight mass analyzer, an ion source, a data acquisition system and an electric control system. The ion source adopts two-stage source acceleration,delayed extraction and dynamic pulse focusing technology. The time-of-flight distance of field-free drift region is about 1 meter. The optical system adopts a solid laser with adjustable frequency of 1-2000 Hz and spots of 20-100 μm. The angle of incidence laser is controlled at 5 degrees. A series of experiments are carried out to further evaluate the instrument performances. It can not only analyze the samples more than 199 kDa, but also achieve isotope resolution at 1000-3000 Da and up to 900(FWHM) at 5000-17000 Da. The minimum detectable concentration of gramicidin is 10 amol/μL, absolute sensitivity can reach up to 2. 56 amol. Independent detection of saliva samples from different targets shows that the instrument has high reproducibility. We identified Escherichia Coli and Shigella spp,which are two common bacteria but difficult to be differentiated by mass spectrometry,showing its potential identification for clinical microorganism. In a summary,this instrument can play a role on clinical examination in the near future.