Based on Ag nanoparticles as the surface-enhanced Raman spectroscopy (SERS)-active nanostructure, the SERS of uric acid was presented in the paper. The absorption spectroscopies of uric acid and the mixture of silver colloids and uric acid were measured. The possible enhancing mechanism of the uric acid on silver colloid was speculated. The characteristic SERS bands of uric acid were tentatively assigned. The influence of absorption time and different ion on the SERS of uric acid were also discussed. The SERS spectral intensity changes linearly with the uric acid concentration, which indicated that the SERS might provide a new kind of direct and fast detecting method for the detection of uric acid. The detection limit of uric acid in silver sol is found to be 1 mg/L.
Metal Nanoparticles ; chemistry ; Silver ; chemistry ; Spectrum Analysis, Raman ; methods ; Surface Properties ; Uric Acid ; analysis

BACKGROUNDA practical problem impeding clinical translation is the limited bone formation seen in artificial bone grafts. Low-pressure/vacuum seeding and dynamic culturing in bioreactors have led to a greater penetration into the scaffolds, enhanced production of bone marrow cells, and improved tissue-engineered bone formation. The goal of this study was to promote more extensive bone formation in the composites of porous ceramics and bone marrow stromal cells (BMSCs).

METHODSBMSCs/β-tricalcium phosphate (β-TCP) composites were subcultured for 2 weeks and then subcutaneously implanted into syngeneic rats that were split into a low-intensity pulsed ultrasound (LIPUS) treatment group and a control group. These implants were harvested at 5, 10, 25, and 50 days after implantation. The samples were then biomechanically tested and analyzed for alkaline phosphate (ALP) activity and osteocalcin (OCN) content and were also observed by light microscopy.

RESULTSThe levels of ALP activity and OCN content in the composites were significantly higher in the LIPUS group than in the control group. Histomorphometric analysis revealed a greater degree of soft tissue repair, increased blood flow, better angiogenesis, and more extensive bone formation in the LIPUS groups than in the controls. No significant difference in the compressive strength was found between the two groups.

CONCLUSIONLIPUS treatment appears to enhance bone formation and angiogenesis in the BMSCs/β-TCP composites.

Animals ; Bone Marrow Cells ; physiology ; Bone Transplantation ; Calcium Phosphates ; pharmacology ; Male ; Osteogenesis ; physiology ; Rats ; Stromal Cells ; Tissue Engineering ; methods ; Transplantation, Isogeneic ; Ultrasonics ; methods