The objective of this study was to develop a novel scaffold imitating the ingredients and their ratios of natural dermal matrix and to evaluate its biological activity. We applied different ratios and different synthetic methods to fabricate nine kinds of cross-linked (CL) collagen/chondroitin sulfate/hyaluronic acid (Co/CS/HA) scaffolds for dermal tissue engineering. On the basis of comparison among the morphology, mechanical properties, and biodegradation rates of scaffolds, we selected the novel scaffold that was fabricated under unique procedures. In the procedures, Co, CS, and HA were firstly synthesized together in the ratio of 9:1:1 to form a membrane that was then CL with 5 mM of 1-ethyl-3-3-dimethylaminopropylcarbodiimide hydrochloride (EDC) (Co-CS-HA/CL 9:1:1). From the results of comparison, we also found that the ratio of 9:1:1 was better than other ratios. So the scaffold of Co-CS-HA/CL 9:1:1 was used as experimental group with the scaffolds of Co-HA/CS CL 9:1:1 and Co-CS/HA CL 9:1:1 as control groups to evaluate their characteristics in vitro. A control group of an open wound without scaffold was supplemented to evaluate their effects on promoting wound healing in vivo. Morphological observation showed that the novel Co-CS-HA/CL 9:1:1 scaffold had uniform and widely interconnected pores with mean diameters of 109 +/- 11 microm and adequate porosity of about 94%. Mechanical property and biodegradation assessment indicated that it had more degradation-resistant and higher elastic modulus than other scaffolds. Metabolic activity assay showed that it could more strongly promote cellular attachment and proliferation. When scaffolds were seeded with allogenic skin fibroblasts and implanted on the dorsum of Sprague-Dawley rats for 6 weeks, the novel Co-CS-HA/CL 9:1:1 skin equivalent could more successfully repair full thickness skin defects in Sprague-Dawley rats. The histology was more approximate to normal skin than those of the controls within 6 weeks. These results demonstrated that the novel CoCS-HA/CL 9:1:1 tri-copolymer has the potential to be used as a scaffold for dermal tissue engineering.

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Although accurate estimations of C50 from sparse binary data are possible, estimates of gamma are biased. Data with 10 or more observations per patient is necessary for accurate estimations of gamma.

Construction of supramolecular structures with internal functionalities is a promising approach to build enzyme‐like cavities. The endo‐functionalized [Pd12L24] and [Pd2L4] coordination cages represent the most successful systems in this regard. However, these systems mainly contain one type of endo‐moiety. We herein provide a solution for the controlled endo‐functionalization of [Pd2L4] cages. Site‐selective introduction of the endo‐functional group was achieved through the formation of heteroleptic [Pd2(LA)2(LB)(LC)] cages. Using two orthogonal steric control elements is the key for the selective formation of the hetero‐assemblies. We demonstrated the construction of two hetero‐cages with a single internal functional group as well as a hetero‐cage with two distinct endohedral functionalities. The endo‐functionalized hetero‐cages bound sulfonate guests with fast‐exchange dynamics. This strategy provides a new solution for the controlled endo‐functionalization of supramolecular cavities.

Collagen presents an attractive biomaterial for tissue engineering because of its excellent biocompatibility and negligible immunogenicity. However, some intrinsic features related to the mechanical stability and thrombogenicity limit its applications in orthopedic and vascular tissue engineering. Photochemical cross-linking is an emerging technique able to stabilize tissue grafts and improve the physicochemical properties of collagen-based structures. However, other important properties of collagen-based structures and the effect of processing parameters on these properties have not been explored. In this study, we aim to investigate the dose dependence of tensile and swelling properties on two parameters, namely, laser energy fluence and rose Bengal photosensitizer concentration. We also study the compression properties using cyclic compression test, long-term stability using subcutaneous implantation, and hematocompatibility using platelets adhesion test, of cross-linked collagen structures. Moreover, because limited optical penetration in turbid media is the major obstacle for light-based techniques, we also characterize the optical properties, which partially determine the effective optical penetration depth in collagen gel samples, during photochemical cross-linking. Laser energy fluence and rose Bengal concentration are important parameters affecting the cross-linking efficiency, which was characterized as the mechanical and the swelling properties, in a dose-dependent manner. Under the experimental conditions in this study, the peak fluence was 12.5 J/cm2 and the minimal rose Bengal concentration for effective cross-linking was >0.00008% (0.786 micromol). Photochemical cross-linking also enhanced the compression strength and long-term stability of collagen structures without compromising the tissue compatibility. Furthermore, photochemical cross-linking reduced platelet adhesion and abolished fibrin mesh formation, thereby improving the hematocompatibility of collagen structures. These results suggest the feasibility of using the photochemically cross-linked collagen structures for orthopedic and vascular tissue engineering. Finally, the effective optical penetration depth in collagen gel samples is wavelength and rose Bengal concentration dependent, and was approximately 12 mm at 514 nm at 0.001% (9.825 micromol), the rose Bengal concentration mostly used in this study.