Biomatter最新文献

A modified sol-gel process for synthesizing nanocrystalline hydroxyapatite powders (nHA) for biomedical applications, using tetrahydrated calcium nitrate [Ca(NO(3))(2)∙4H(2)O] and phosphorous pentoxide [P(2)O(5)] as precursor, is presented and discussed. The powders were washed and heat-treated at different temperatures and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The total process time reached with this modified process was less than 16 h. The results showed that there was an increment in size of the HA nanocrystals (nHA) when treated at different temperatures, ranging from 30 nm for the sample treated at 600°C to 500 nm for the sample heat-treated at 1,200°C.

Poly (lactic-co-glycolic acid) (PLGA) coatings on implant materials are widely used in controlled drug delivery applications. Typically, such coatings are made with non-porous films. Here, we have synthesized a thin PLGA film coating with a highly ordered microporous structure using a simple and inexpensive water templating "breath figure" technique. A single stage process combining spin coating and breath figure process was used to obtain drug incorporated porous thin films. The films were characterized by scanning electron microscope (SEM) to observe the surface and bulk features of porosity and also, degradation pattern of the films. Moreover, the effect of addition of small amount of poly (ethylene glycol) (PEG) into PLGA was characterized. SEM analysis revealed an ordered array of ~2 µm sized pores on the surface with the average film thickness measured to be 20 µm. The incorporation of hydrophilic poly (ethylene glycol) (PEG) enhances pore structure uniformity and facilitates ingress of water into the structure. A five week in vitro degradation study showed a gradual deterioration of the breath figure pores. During the course of degradation, the surface pore structure deteriorates to initially flatten the surface. This is followed by the formation of new pinprick pores that eventually grow into a macroporous film prior to film breakup. Salicylic acid (highly water soluble) and Ibuprofen (sparingly water soluble) were chosen as model drug compounds to characterize release rates, which are higher in films of the breath figure morphology rather than in non-porous films. The results are of significance in the design of biodegradable films used as coatings to modulate delivery.

In this work we describe the fabrication of a biocompatible hydrophilic scaffold composed of cross-linked gelatin that mimics the porous three-dimensional structure of pulmonary tissue as well as its water content and mechanical properties. The lung replica also reproduces the characteristic sonographic signs of pulmonary interstitial syndrome, the B-lines or ultrasound lung comets.

Tissue destruction, pain and loss of function in chronically inflamed tissues can result from noxious agents released from myeloperoxidase (MPO) and its highly reactive product hypochlorous acid (HOCl) or proteases such as neutrophil elastase (NE). Currently there exists a high demand for medications that provide gentle treatments, free from side effects inherent in those prescribed today. One method to circumvent side effects is through the use of locally applied drug delivery. In contrast to systemic therapy, the main advantages of transport systems are the low dosages of drug with a time-controlled delivery. The aim of this study was to ascertain interactions of NE and its inhibitor α(1)-antitrypsin (AT), the influence of hypochlorous acid (HOCl), as well as its scavengers, in order to define an effective mixture of drugs acting in a synergistic way which can be applied by means of drug delivery systems. These investigations determine the effective amounts of AT/HOCl-scavengers that drug mixtures need for delivery under inflammatory conditions in order to prevent tissue damage. AT was shown to inhibit NE in a dose-dependent manner, whereas a physiological concentration of 1.14 µM AT caused a significant NE inhibition (78%, pH 7.5). The concomitant existence of MPO/HOCl inactivated AT in a dose-dependent manner as well. To regain AT efficacy, HOCl-scavengers, such as L-methionine, α-aminosalicylic acid and cefoperazone were additionally applied. Finally, AT was assembled as surface layer onto layer-by-layer biopolymer-coated microcarriers and carrier phagocytosis by polymorphonuclear leukocytes could be shown.

It has long been known that the interfacial relationship between synthetic materials and tissue is influential in the success of implant materials. Instability at the implant interface has been shown, in some cases, to lead to complete implant failure. Bioceramics, and in particular calcium phosphates, form a large fraction of the implantable devices on the market today due to the biocompatibility they exhibit in contact with bone and tooth-like tissues. The characterization of such bioceramic-tissue interfaces has played a crucial role in understanding the behavior of bioceramics in vivo. In this review, we shed light on the preparation methods, technological approaches and key advances in resolving the interface between calcium phosphate bioceramics and bone, and share a future outlook on this field.

Regeneration of myocardium through regenerative therapy and tissue engineering is appearing as a prospective treatment modality for patients with end-stage heart failure. Focusing on this area, this review highlights the new developments and challenges in the regeneration of myocardial tissue. The role of various cell sources, calcium ion and cytokine on the functional performance of regenerative therapy is discussed. The evolution of tissue engineering and the role of tissue matrix/scaffold, cell adhesion and vascularisation on tissue engineering of cardiac tissue implant are also discussed.

The vascularization of new tissue within a reasonable time is a crucial prerequisite for the success of different cell- and material-based strategies. Considering that angiogenesis is a multi-step process involving humoral and cellular regulatory components, only in vivo assays provide the adequate information about vessel formation and the recruitment of endothelial cells. The present study aimed to investigate if neonatal human dermal fibroblasts could influence in vivo neovascularization. Results obtained showed that fibroblasts were able to recruit endothelial cells to vascularize the implanted matrix, which was further colonized by murine functional blood vessels after one week. The vessels exhibited higher levels of hemoglobin, compared with the control matrix, implanted without fibroblasts, in which no vessel formation could be observed. No significant differences were detected in systemic inflammation. The presence of vessels originated from the host vasculature suggested that host vascular response was involved, which constitutes a fundamental aspect in the process of neovascularization. Fibroblasts implanted within matrigel increased the presence of endothelial cells with positive staining for CD31 and for CD34 and the production of collagen influencing the angiogenic process and promoting the formation of microvessels. New strategies in tissue engineering could be delineated with improved angiogenesis using neonatal fibroblasts.

Chondroitin sulfate is a major component of the extracellular matrix in both the central and peripheral nervous systems. Chondroitin sulfate is upregulated at injury, thus methods to promote neurite extension through chondroitin sulfate-rich matrices and synthetic scaffolds are needed. We describe the use of both chondroitin sulfate and a novel chondroitin sulfate-binding peptide to control the release of nerve growth factor. Interestingly, the novel chondroitin sulfate-binding peptide enhances the controlled release properties of the chondroitin sulfate gels. While introduction of chondroitin sulfate into a scaffold inhibits primary cortical outgrowth, the combination of chondroitin sulfate, chondroitin sulfate-binding peptide and nerve growth factor promotes primary cortical neurite outgrowth in chondroitin sulfate gels.

For treating colonic diseases, conventional oral drug delivery systems are not effective, as they fail to reach the appropriate site of action. Thus, there is a need to develop effective and safe therapy for the treatment of colonic disorders. The aim of the present study was to design a colon-specific delivery system for an anti-inflammatory drug, mesalamine, with minimal degradation and optimum delivery of the drug with relatively higher local concentration, which may provide more effective therapy for inflammatory bowel disease including Crohn disease and ulcerative colitis. Factorial designs (four factors and two levels) for eudragit S-100 (pH-dependent polymer)-coated, pectin (natural polysaccharides)-based microspheres of mesalamine were constructed and conducted in a fully randomized manner to study all possible combinations. Based on the desirability function formulation, F14 was found to be the best formulation. The overall desirability coefficient of formulation F14 was found to be 0.825. The formulation F14 was subjected to in vitro release studies, and the results were evaluated kinetically and statistically. The microspheres started releasing the drug at the beginning of 7th hour, which corresponds to the arrival time at proximal colon. The cumulative percent drug release for formulation F14 at the end of 16 h was found to be 98%. The release kinetics showed that the release followed the Higuchi model, and the main mechanism of drug release was diffusion. The study presents a new approach for colon-specific drug delivery.

In this study, the development and characterization of novel polymer blends based on chitosan-poly (vinyl alcohol) and physically cross-linked by freeze-thaw method for possible use in a variety of biomedical application is reported. The present investigation deals with designing savlon-loaded blend hydrogels (coined as cryogels) of poly (vinyl alcohol) (PVA) and chitosan by repeated freeze-thaw method and their characterization by SEM and FTIR techniques. The FTIR spectra clearly reveal that savlon-loaded chitosan and PVA blends are bonded together through hydrogen bonding. The SEM analysis suggests that cryogels show a well-defined porous morphology. The prepared cryogels were also investigated for swelling and deswelling behaviors. The results reveal that both the swelling and deswelling behaviors greatly depend on factors like chemical composition of the cryogels, number of freeze-thaw cycles, pH and temperature of the swelling bath. The savlon-loaded blends were also investigated for their in vitro blood compatibility and antibacterial activity.