Multi-Material Stereolithography: Spatially-Controlled Bioactive Poly(Ethylene Glycol) Scaffolds for Tissue Engineering

Challenges remain in tissue engineering to control the spatial and temporal mechanical and biochemical architectures of scaffolds. Unique capabilities of stereolithography (SL) for fabricating multi-material spatially-controlled bioactive scaffolds were explored in this work. To accomplish multi-material builds with implantable materials, a new mini-vat setup was designed, constructed and placed on top of the existing build platform to allow for accurate and selfaligning X-Y registration during fabrication. Precise quantities of photocrosslinkable solution were added to and removed from the mini-vat using micro-pipettes. The mini-vat setup allowed the part to be easily removed and rinsed and different photocrosslinkable solutions could be easily removed and added to the vat to aid in multi-material fabrication. Two photocrosslinkable hydrogel biopolymers, poly(ethylene glycol dimethacrylate) (PEG-dma, molecular wt 1,000) and poly(ethylene glycol)-diacrylate (PEG-da, molecular wt 3,400), were used as the primary scaffold materials, and controlled concentrations of fluorescently labeled dextran or bioactive PEG were prescribed and fabricated in different regions of the scaffold using SL. The equilibrium swelling behavior of the two biopolymers after SL fabrication was determined and used to design constructs with the specified dimensions at the swollen state. Two methods were used to measure the spatial gradients enabled by this process with multi-material spatial control successfully demonstrated down to 500-µm. First, the presence of the fluorescent component in specific regions of the scaffold was analyzed with fluorescent microscopy. Second, human dermal fibroblast cells were seeded on top of the fabricated scaffolds with selective bioactivity, and phase contrast microscopy images were used to show specific localization of cells in the regions patterned with bioactive PEG. The use of multi-material SL and the relative ease of conjugating different bioactive ligands or growth factors to PEG allows for the fabrication of tailored three-dimensional constructs with specified spatially-controlled bioactivity.Mechanical Engineerin

Bioactive ceramic-reinforced composites for bone augmentation

Biomaterials have been used to repair the human body for millennia, but it is only since the 1970s that man-made composites have been used. Hydroxyapatite (HA)-reinforced polyethylene (PE) is the first of the ‘second-generation’ biomaterials that have been developed to be bioactive rather than bioinert. The mechanical properties have been characterized using quasi-static, fatigue, creep and fracture toughness testing, and these studies have allowed optimization of the production method. The in vitro and in vivo biological properties have been investigated with a range of filler content and have shown that the presence of sufficient bioactive filler leads to a bioactive composite. Finally, the material has been applied clinically, initially in the orbital floor and later in the middle ear. From this initial combination of HA in PE other bioactive ceramic polymer composites have been developed

Bioactive SrO-SiO2 glass with well-ordered mesopores: Characterization, physiochemistry and biological properties

For a biomaterial to be considered suitable for bone repair it should ideally be both bioactive and have a capacity for controllable drug delivery; as such, mesoporous SiO2 glass has been proposed as a new class of bone regeneration material by virtue of its high drug-loading ability and generally good biocompatibility. It does, however, have less than optimum bioactivity and controllable drug delivery properties. In this study, we incorporated strontium (Sr) into mesoporous SiO2 in an effort to develop a bioactive mesoporous SrO–SiO2 (Sr–Si) glass with the capacity to deliver Sr2+ ions, as well as a drug, at a controlled rate, thereby producing a material better suited for bone repair. The effects of Sr2+ on the structure, physiochemistry, drug delivery and biological properties of mesoporous Sr–Si glass were investigated. The prepared mesoporous Sr–Si glass was found to have an excellent release profile of bioactive Sr2+ ions and dexamethasone, and the incorporation of Sr2+ improved structural properties, such as mesopore size, pore volume and specific surface area, as well as rate of dissolution and protein adsorption. The mesoporous Sr–Si glass had no cytotoxic effects and its release of Sr2+ and SiO44− ions enhanced alkaline phosphatase activity – a marker of osteogenic cell differentiation – in human bone mesenchymal stem cells. Mesoporous Sr–Si glasses can be prepared to porous scaffolds which show a more sustained drug release. This study suggests that incorporating Sr2+ into mesoporous SiO2 glass produces a material with a more optimal drug delivery profile coupled with improved bioactivity, making it an excellent material for bone repair applications. Keywords: Mesoporous Sr–Si glass; Drug delivery; Bioactivity; Bone repair; Scaffold

Elaboration of New Method of Deep Processing of Caro-tene-containing Raw Materials Into Nanoadditives with the Use of Cryogenic Freezing and Fine-dispersed Grinding

The aim of the work is elaboration of principally new cryogenic method of deep processing of carotene-containing vegetable raw material (CCVRM) such as carrot, pumpkin, sweet Bulgarian pepper, tomato, sea buckthorn, apricot using cryogenic freezing and fine-dispersed grinding.The new method of deep processing leads to more full extracting and removal of β-carotene from the state, bound with biopolymers into free and hydrophilic form. The mechanism of these processes was presented. It was established, that mass share of β-carotene in cryopuree, received by the new method, exceeds its content in initial (fresh) CCVRM in 3,0…3,5 times.The regularities of growth and transformation of carotenoids separately at freezing with different high speeds and low-temperature grinding of CCYRM were established. It was demonstrated, that at cryogenic freezing take place quantitative increase of mass share of carotenoids in 2,0…2,5 times comparing with initial (fresh) raw material depending on freezing speed and type of CCVRM. That is it was demonstrated, that frozen carotene-containing vegetable raw material contains 2,0…2,5 times more β-carotene than fresh one. Mechanism of these processes was presented.It was demonstrated, that cryopuree of CCVRM, received using new methods of deep processing, exceeds the initial (fresh) raw material by the content not only β-carotene but also other low-molecular bioactive substances: L-ascorbic acid – in 2,0…2,2 times, phenol compounds – in 1,7…1,8 times, tanning substances – in 1,5…1,7 times). That is they have principally new chemical composition, because practically all bioactive substances (BAS) in cryopuree are in nanosize form and easily assimilated by human organism

Cellulose: from biocompatible to bioactive material

International audienceSince the papyri, cellulose has played a significant role in human culture, especially as paper. Nowadays, this ancient product has found new scientific applications in the expanding sector of paper-based technology. Among paper-based devices, paper-based biosensors raise a special interest. The high selectivity of biomolecules for target analytes makes these sensors efficient. Moreover, simple paper-based detection devices do not require hardware or specific technical skill. They are inexpensive, rapid, user-friendly and therefore highly promising for providing resource-limited settings with point-of-care diagnostics. The immobilization of biomolecules onto cellulose is a key step in the development of these sensing devices. Following an overview of cellulose structural features and physicochemical properties, this article reviews current techniques for the immobilization of biomolecules on paper membranes. These procedures are categorized into physical, biological and chemical approaches. There is no universal method for biomolecule immobilization. Thus, for a given paper-based biochip, each strategy can be considered

Activity Tests of Bioactive Material of Salung Leaf (Psychotria viridiflora Reinw. Ex. Blume) against Salmonella thypi Bacteria In Vitro And In Vivo

Activity test of bioactive material of Salung leaf (Psychotria viridiflora Reinw. ex. Blume) against Salmonella thypi in vitro and in vivo has been carried out. Bioactive material was obtained from the maceration and followed by fractionation of liquid-liquid fractionation. Antibacterial activity test performed in vitro to determine the value of the minimum inhibitory concentration (MIC) and in vivo to determine the ability of bioactive cure diarrhea in in rats (Rattus norvegicus) infected by Salmonella typhi. Treatment of bioactive material given is 0, 10, 50 and 100 mg kg-1 of weight. The results showed that the MIC of salung leaf’s bioactive material to Salmonella typhi was 250 μg mL-1. Bioactive ingredient at dose of 10 and 50 mg kg-1 were able to decrease the number of bacterial colonies to 4.14x106 cfu g-1 and 5.4x105 cfu g-1, less than 5.04x106 cfu g-1 as control. Bioactive material in weight of 100 mg kg-1 of weight could reduce the population of Salmonella typhi to zero after 12 days of treatment. The ability to reduce the amount of bacterial colonies of the bioactive material 100 mg kg-1 of weight is equal to the ability of positive control chloramphenicol 10 mg kg-1 of weight.Telah dilakukan uji aktivitas bahan bioaktif dari daun Salung (Psychotria viridiflora Reinw. ex. Blume) terhadap bakteri Salmonella thypi secara in vitro dan in vivo. Bahan bioaktif diperoleh dari proses maserasi dan dilanjutkan dengan fraksinasi secara fraksinasi cair-cair (FCC), Pengujian aktivitas antibakteri dilakukan secara in vitro untuk menentuan nilai konsentrasi hambat minimum (KHM) dan pengujian secara in vivo pada tikus putih (Rattus norvegicus) untuk mengetahui kemampuan bioaktif menyembuhkan penyakit diare yang diinfeksi dengan Salmonella typhi. Perlakuan bahan bioaktif yang diberikan 0, 10, 50 dan 100 mg/kgbb. Hasil penelitian menunjukkan bahwa KHM bahan bioaktif dari daun salung terhadap bakteri Salmonella typhi yaitu 250 μg/ml. Bahan bioaktif pada dosis 10 mg/kgbb dan 50 mg/kg mampu menurunkan jumlah koloni bakteri menjadi 4,14x106 dan 5,4x105 cfu/g, lebih sedikit dibanding kontrol 5,04 x 106 cfu/g. Bahan bioaktif 100 mg/kgbb dapat menurunkan populasi bakteri Salmonella typhi sampai nol setelah 12 hari pengobatan. Kemampuan bahan bioaktif 100 mg/kgbb sama dengan kontrol positif kloramfenikol 10 mg/kgbb

SCREENING SPONGES FOR BACTERIOCIDE TO BE USED IN SHRIMP CULTURE

Sponges are suspected of having potential for producing bioactive material that canbe used for various purposes. The experiment aimed at identifying sponges which couldproduce bioactive materials for fish health management purpose

Conceptual design of harvesting energy system for road application

Energy harvesting becomes more and more important in our life. It refers to the practice of acquiring energy from the environment which would be otherwise wasted and converting it into usable electric energy. For this, every kind of energy can be exploited such as solar, wind or strain and kinetic energy. The idea is to propose a conceptual design that will carry out a suitable energy harvesting conversion to be applied for road application. Harvesting energy using piezoelectric generators has been chosen for this project. The project conduct a simulation analysis using a piezoelectric generator based on a model by S Roundy and P K Wright. The data used from a 15 mm x 3.2 mm x 0.14 mm single layer piezoelectric bending element which produce 0.95mW with a 1.727e6 Nm of input stress. The simulation is done using MATLAB-Simulink-SimPowerSystems which also tested with others value by Luigi Pinna et al.. Piezoelectric generator can be one of the green solutions for sustainable development in energy generation

Bioactive composites for bone tissue engineering

One of the major challenges of bone tissue engineering is the production of a suitable scaffold material. In this review the current composite materials options available are considered covering both the methods of both production and assessing the scaffolds. A range of production routes have been investigated ranging from the use of porogens to produce the porosity through to controlled deposition methods. The testing regimes have included mechanical testing of the materials produced through to in vivo testing of the scaffolds. While the ideal scaffold material has not yet been produced, progress is being made

Improved Flexural Properties of Experimental Resin Composites Functionalized with a Customized Low-Sodium Bioactive Glass

This study evaluated the flexural properties of an experimental composite series functionalized with 5-40 wt% of a low-Na F-containing bioactive glass (F-series) and compared it to another experimental composite series containing the same amounts of the conventional bioactive glass 45S5 (C-series). Flexural strength and modulus were evaluated using a three-point bending test. Degree of conversion was measured using Fourier-transform infrared spectroscopy. Weibull analysis was performed to evaluate material reliability. The control material with 0 wt% of bioactive glass demonstrated flexural strength values of 105.1-126.8 MPa). In the C-series, flexural strength ranged between 17.1 and 121.5 MPa and was considerably more diminished by the increasing amounts of bioactive glass than flexural strength in the F-series (83.8-130.2 MPa). Analogously, flexural modulus in the C-series (0.56-6.66 GPa) was more reduced by the increase in bioactive glass amount than in the F-series (5.24-7.56 GPa). The ISO-recommended "minimum acceptable" flexural strength for restorative resin composites of 80 MPa was achieved for all materials in the F-series, while in the C-series, the materials with higher bioactive glass amounts (20 and 40 wt%) failed to meet the requirement of 80 MPa. The degree of conversion in the F-series was statistically similar or higher compared to that of the control composite with no bioactive glass, while the C-series showed a declining degree of conversion with increasing bioactive glass amounts. In summary, the negative effect of the addition of bioactive glass on mechanical properties was notably less pronounced for the customized bioactive glass than for the bioactive glass 45S5; additionally, mechanical properties of the composites functionalized with the customized bioactive glass were significantly less diminished by artificial aging. Hence, the customized bioactive glass investigated in the present study represents a promising candidate for functionalizing ion-releasing resin composites