The studies of FT-IR and CD spectroscopy on catechol oxidase I from tobacco

Collagen immobilization on ultraviolet light-treated poly(ethylene terephthalate)

The present article is focused on the studies regarding the effects of ultraviolet (UV) light on poly(ethylene terephthalate) (PET) films surfaces using scanning electron microscopy (SEM), Fourier transform infrared, X-ray photoelectron spectrometry (XPS), and atomic force microscopy (AFM) measurements, subsequent to collagen immobilization. UV treatment influences the surface energy of polymers as the result of the polymer chain breaking, followed by insertion of oxygen-containing functional groups. Accordingly, after UV light treatment, collagen was adsorbed on the PET surfaces in different proportions. Significant changes in the surface topography appeared after collagen immobilization on UV-treated PET films, and they were put in evidence by SEM and tapping-mode AFM experiments. XPS measurements demonstrated the adsorption of collagen on PET UV light-altered surfaces by increasing of nitrogen content. The cytocompatibility tests using stem cells have shown good results for all treated polymers.

Preparation of three-dimensional fibroin/collagen scaffolds in various pH conditions

Three dimensional (3-D) fibroin/collagen scaffolds are the novel fibroin based scaffolds derived from aqueous solution. In this article, we investigated the effect of pH on the formation of fibroin/collagen scaffolds. In the range of pH from 4 to 8.5, the fibroin/collagen scaffolds with good porous structures can be prepared using freeze-drying method, which would facilitate the adding of other biopolymers. The structures of different fibroin-based scaffolds were investigated with FTIR and DSC, which indicated that the interaction of fibroin and collagen affected the methanol-induced transformation of fibroin from random-coil to beta-sheet conformation. The mechanical properties were also studied. The results mean that all the fibroin-based scaffolds prepared in various pH values had better mechanical properties than other reported fibroin scaffolds. Since the fibroin/collagen scaffolds can be prepared in the range of pH from 4 to 8.5, it is very easy to prepare different multifunctional scaffolds such as fibroin/collagen/chitosan scaffolds and fibroin/collagen/heparin scaffolds in acidic or neutral conditions. These new fibroin-based blend materials extend the range of biomaterial properties that can promote the use in biomedical applications such as drug release and tissue engineering.

Fibroin/collagen hybrid hydrogels with crosslinking method: Preparation, properties, and cytocompatibility

Substrate stiffness is an important physical factor in the response of many cell types. Although protein-based hydrogels are widely used as cell-culture substrates because of their resemblance to the natural extracellular matrix (ECM) and complex signaling, their rigidity should be further increased to facilitate the adhesion and growth of cells. In this study, fibroin/collagen hydrogels having suitable stiffness were prepared directly by adding 1-ethyl-3-(3-dimethylaminoprophy) carbodiimide hydrochloride (EDC) in fibroin/collagen solution to induce crosslinking. The storage moduli of these crosslinked hydrogels are above 3 kPa, and even exceed 10 kPa, having stronger mechanical strength than that of previously reported protein-based hydrogels. Furthermore, the crosslinked hydrogels can maintain their configuration above 80(o)C, which proves their increased thermal stability. Although crosslinked, the hydrogels still maintain the mobility of fibroin molecules. The growth of vascular smooth muscle cells (VSMCs) in fibroin/collagen gels indicates that the crosslinking reaction has no negative influence on the biocompatibility of fibroin/collagen hydrogels. The fibroin/collagen hydrogels are more propitious to the growth of cells compared with fibroin/collagen scaffolds. Because of their inherent biocompatibility, excellent mechanical and thermal properties, and green preparation process, the fibroin/collagen hydrogels would become promising scaffolds for tissue engineering.

Analytical performances of FT-IR spectrometry and imaging for concentration measurements within biological fluids, cells, and tissues

FT-IR spectrometry has proved to be a useful tool for determining a series of plasma molecular concentrations. Dedicated experiments were first performed to test the analytical performance that could be obtained by FT-IR spectrometry using a synthesized N3-peptide exhibiting a -N3 absorption centered at 2110 cm(-1), a spectral region where no organic material of biological samples absorbs. Further, we investigated whether this technology was able to allow quantification of metabolic parameters (glucose and lactic acid) within plasma, cells, and tissues as an alternative method to the "classical" biochemical approaches, which require sophisticated biological material treatment and expensive reagents. For this purpose we used a series of plasma samples to determine glucose and lactic acid concentrations, which are common markers of cancer growth. We compared the results of the main spectral data treatments commonly achieved for FT-IR data analysis, such as univariate (Beer-Lambert) or multivariate (PLS) calibrations, as well as the deconvolution of the spectral interval of interest (1200-900 cm(-1)). No significant differences were found regarding the analytical performances of these methods. Spectral deconvolution was finally undertaken on cultured and on xenografted cells (U87 glial cells implied in human gliomas) to determine glucose and lactic acid concentrations. In this case, qualification was allowed by FT-IR imaging on the cellular models since biochemical approaches are not efficient to reach metabolic concentrations at the cellular level while keeping tissue organization.