Type I collagen-templated assembly of silver nanoparticles and their application in surface-enhanced Raman scattering

Silver nanoparticles (Ag NPs) are one of the active substrates that are employed extensively in surface-enhanced Raman scattering (SERS), and aggregations of Ag NPs play an important role in enhancing the Raman signals. In this paper, we fabricated two kinds of SERS-active substrates utilizing the electrostatic adsorption and superior assembly properties of type I collagen. These were collagen-Ag NP aggregation films and nanoporous Ag films.

Fabrication, characterization, and application in surface-enhanced Raman spectrum of assembled type-I collagen-silver nanoparticle multilayered films

In this paper, we report a facile method for the fabrication of type-I collagen-silver nanoparticles (Ag NPs) multilayered films by utilizing type-I collagen as a medium. These samples were characterized by UV-vis spectra photometer, atomic force microscopy, scanning electron microscopy, and Fourier transform IR spectrum. Experimental results show that collagen molecules serve as effective templates to assemble Ag NPs into multilayer films. These samples exhibit high surface-enhanced Raman scattering (SERS) enhancement abilities.

Type I collagen-mediated synthesis of noble metallic nanoparticles networks and the applications in Surface-Enhanced Raman Scattering and electrochemistry

In this paper, we demonstrated an effective enviromentally friendly synthesis route to prepare noble metallic (Au, Ag, Pt and Pd) nanoparticles (NPs) networks mediated by type I collagen in the absence of any seeds or surfactants. In the reactions, type I collagen served as stabilizing agent and assembly template for the synthesized metallic NPs. The hydrophobic interaction between collagen and mica interface as well as the hydrogen bonds between inter- and intra-collagen molecules play important roles in the formation of collagen-metallic NPs networks. The noble metallic NPs networks have many advantages in the applications of Surface-Enhanced Raman Scattering (SERS) and electrochemistry detection. Typically, the as-prepared Ag NPs networks reveal great Raman enhancement activity for 4-ATP, and can even be used to detect low concentration of DNA base, adenine.

Electrodeposition of platinum nanoclusters on type I collagen modified electrode and its electrocatalytic activity for methanol oxidation

We firstly reported a novel polymer matrix fabricated by type I collagen and polymers, and this matrix can be used as nanoreactors for electrodepositing platinum nanoclusters (PNCs). The type I collagen film has a significant effect on the growth of PNCs. The size of the platinum nanoparticles could be readily tuned by adjusting deposition time, potential and the concentration of electrolyte, which have been verified by field-emitted scanning electron microscopy (FE-SEM). Furthermore, cyclic voltammetry (CV) has demonstrated that the as-prepared PNCs can catalyze methanol directly with higher activity than that prepared on PSS/PDDA film, and with better tolerance to poisoning than the commercial E-TEK catalyst. The collagen-polymer matrix can be used as a general reactor to electrodeposit other metal nanostructures.

Type I collagen-mediated synthesis and assembly of UV-photoreduced gold nanoparticles and their application in surface-enhanced Raman scattering

We reported a simple method to synthesize gold nanoparticles (NPs) by photoreducing HAuCl4 in acetic acid solution in the presence of type I collagen. It was found that the collagen takes an important role in the formation of gold NPs. The introduction of collagen made the shape of the synthesized gold nanocrystals change from triangular and hexangular gold nanoplates to size-uniform NPs. On the other hand, thanks to the special characters of collagen molecules, such as its linear nanostructure, are positively charged when the pH < 7, and the excellent self-assembly ability, photoreduced gold NPs were assembled onto the collagen chains and formed gold NPs films and networks. A typical probe molecule, 4-aminothiophenol, was used to test the surface-enhanced Raman scattering activity of these gold NPs films and networks and the results indicated good Raman activity on these substrates.

Competitive adsorption between bovine serum albumin and collagen observed by atomic force microscope

Atomic force microscopy (AFM) was used to study the competitive adsorption between bovine serum albumin (BSA) and type I collagen on hydrophilic and hydrophobic silicon wafers. BSA showed a grain shape and the type I collagen displayed fibril-like molecules with relatively homogeneous height and width, characterized with clear twisting (helical formation). These AFM images illustrated that quite a lot of type I collagen appeared in the adsorption layer on hydrophilic surface in a competitive adsorption state, but the adsorption of BSA was more preponderant than that of type I collagen on hydrophobic silicon wafer surface. The experiments showed that the influence of BSA on type I collagen adsorption on hydrophilic surface was less than that on hydrophobic surface.

Performance inhomogeneity of gelatin during gelation process

The structural and performance inhomogeneities of gelatin gel can directly affect its application as a kind of functional material. The structural inhomogeneity of gelatin caused by the uneven and unstable temperature field has been analyzed by the finite element method in our previous work. Further in this paper, the performance inhomogeneity of gelatin which is closely connected with the actual application is numerically analyzed during the gelation process, which includes the inhomogeneities of the optical and mechanical properties of gelatin gels. The time required for reaching the gel point at different spatial grids is exhibited and discussed. The calculated results also show that the equilibrium shear modulus of gelatin is dependent on the thermal history.

Numerical simulation of coil-helix transition processes of gelatin

Gelatin is widely used in food, pharmaceutical, and photographic industries due to the coil-helix transition, whereas the structural inhomogeneity considerably affects its essential properties closely connecting with the industrial applications. The spatially structural inhomogeneity of the gelatin caused by the uneven and unstable temperature field is analyzed by the finite element method during the cooling-induced coil-helix transition process. The helix conversion and the crosslinking density as functions of time and spatial grid are calculated by the incremental method. A length distribution density function is introduced to describe the continuous length distributions of two kinds of triple helices.

Co-electrospun poly(lactide-co-glycolide), gelatin, and elastin blends for tissue engineering scaffolds

In this study, we describe composite scaffolds composed of synthetic and natural materials with physicochemical properties suitable for tissue engineering applications. Fibrous scaffolds were co-electrospun from a blend of a synthetic biodegradable polymer (poly(lactic-co-glycolic acid), PLGA, 10% solution) and two natural proteins, gelatin (denatured collagen, 8% solution) and (x-elastin (20% solution) at ratios of 3:1:2 and 2:2:2 (v/v/v). The resulting PLGA-gelatin-elastin (PGE) fibers were homogeneous in appearance with an average diameter of 380 80 mn, which was considerably smaller than fibers made under identical conditions from the starting materials (PLGA, 780 +/- 200 nm; gelatin, 447 +/- 1.23 nm; elastin, 1060 170 nm). Upon hydration, PGE fibers swelled to an average fiber diameter of 963 +/- 132 nm, but did not disintegrate. Importantly, PGE scaffolds were stable in an aqueous environment without crosslinking, and were more elastic than those made of pure elastin fibers. To investigate the cytocompatibility of PGE, we cultured H9c2 rat cardiac myoblasts and rat bone marrow stromal cells (BMSCs) on fibrous PGE scaffolds. We found that myoblasts grew equally as well or slightly better on the scaffolds than on tissue-culture plastic. Microscopic evaluation confirmed that myoblasts reached confluence on the scaffold surfaces while simultaneously growing into the scaffolds.

Surface modification of poly(L-lactic acid) to improve its cytocompatibility via assembly of polyelectrolytes and gelatin

Poly(L-lactide) (PLLA) surface was modified via aminolysis by poly(allylamine hydrochloride) (PAH) at high pH and subsequent electrostatic self-assembly of poly(sodium styrenesulfonate) (PSS) and PAH, and the process was monitored by X-ray photoelectron spectroscopy (XPS) and contact angle measurement. These modified PLLAs were then used as charged substrates for further incorporation of gelatin to improve their cytocompatibility. The amphoteric nature of the gelatin was exploited and the gelatin was adsorbed to the negatively charged PLLA/PSS and positively charged PLLA/PAH at pH = 3.4 and 7.4, respectively. XPS and water contact angle data indicated that the gelatin adsorption at pH = 3.4 resulted in much higher surface coverage by gelatin than at pH = 7.4. All the modified PLLA surfaces became more hydrophilic than the virgin PLLA. Chondrocyte culture was used to test the cell attachment, cell morphology and cell viability on the modified PLLA substrates.