Deformation characteristics of hydrogel products based on cross-linked hyaluronic acid.

BACKGROUND: The cross-linked hyaluronic acid (HA) fillers are the viscoelastic hydrogel with a dominant elasticity rather than a viscosity as a useful medical device in the soft tissue augmentation. These HA fillers undergo deformation to begin the biodegradation by the biochemical and physical environment of the body, and result of deformations are closely related to clinical performance. AIMS: The specific equation of molding index is newly generated and proved with Collin's equation, which is used for strong elastomers, for selecting optimal product in facial treatment. METHODS: In this study, the results of amplitude sweep test from five marketed HA fillers were mathematically demonstrated for the proper clinical application. RESULTS: The increment of loss modulus by deformation was evaluated as a useful factor for the maintenance of optimal shape molding performance and resistance to external deformation of the cross-linked HA gel. From this study, the equation of molding index for weak viscoelastic hydrogels like HA products can be applied for choosing which products even in aesthetic plastic field. This molding index equation is compared to Collins' equation that index of deformation as elastomer like rubber and then found the positive correlation between two equations. CONCLUSION: This study could provide a basic theory that achieve useful clinical performance according to characteristics among many types of medical devices based on the molding index.

Formation of Silver Nanoparticles Using Fluorescence Properties of Chitosan Oligomers.

In this study, silver chloride nanoparticles (AgCl NPs) were prepared using chitosan oligomer (CHI) and chitosan oligomer derivatives (CHI-FITC). The CHI and CHI-FITC were used as markers to confirm the formation of AgCl NPs using their fluorescence properties as well as stabilizers. The fluorescence properties of CHI and CHI-FITC were monitored by a luminescence spectrophotometer, and the morphology of the AgCl NPs was further confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The fluorescence of CHI and CHI-FITC was quenched by the formation of AgCl NPs, and the Stern-Volmer equation was used to compare the two types of stabilizer. The CHI and CHI-FITC stabilizer were linear and nonlinear, respectively, with respect to the Stern-Volmer equation, and considered to be usable as fluorescence indicators to confirm the formation behavior of AgCl NPs through fluorescence quenching.

Fluorescent Property of Chitosan Oligomer and Its Application as a Metal Ion Sensor.

An aqueous solution was successfully prepared using a low-molecular-weight chitosan oligomer and FITC, and its structural and fluorescent properties were observed by using ¹H NMR, 13C NMR, FT-IR, XRD, UV-Vis, and PL spectrometry. Its application as a metal ion sensor was also evaluated. The fluorescence in the water-soluble chitosan oligomer was a result of the carbamato anion (NHCOO-), and a synthesized FITC-labeled chitosan oligomer exhibited an effective detection effect for copper ion as well as energy transfer by the ion near FITC that caused a fluorescence decrease (quenching). The chitosan oligomer was confirmed to be applicable as a selective and sensitive colorimetric sensor to detect Cu2+.