|Articles about Biomaterials|
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| Efficacy of an intratumoral controlled release formulation of clusterin antisense oligonucleotide complexed with chitosan containing paclitaxel or docetaxel in prostate cancer xenograft models
Springate, C. M., J. K. Jackson, et al. (2005), Cancer Chemother Pharmacol 56(3): 239-47.
Abstract: PURPOSE: To develop and evaluate an injectable, controlled release delivery system for a phosphorothioate antisense oligonucleotide (ASO) based on complexed ASO:chitosan dispersed in a biodegradable polymeric paste for intratumoral treatment of solid tumors. METHODS: Clusterin ASO was complexed with chitosan particles and incorporated into a paste based on a 60:40 blend of methoxy-poly(ethylene glycol) (MePEG) and triblock copolymer of poly(D,L: -lactic acid-co-caprolactone)-PEG-(D,L: -lactic acid-co-caprolactone). In vitro release profiles of clusterin ASO into phosphate-buffered saline at 37 degrees C were obtained under sink conditions and assayed by anionic exchange high-performance liquid chromatography. In vivo efficacy studies were carried out in human prostate PC-3 and LNCaP tumors grown subcutaneously in mice. Paste formulations of clusterin ASO with or without paclitaxel or docetaxel were injected intratumorally and tumor volumes and serum prostate specific antigen (PSA) levels were measured. RESULTS: Controlled release of clusterin ASO was obtained over several weeks. The rate and extent of ASO release was proportional to the ratio of ASO to chitosan in the paste. Treatment of mice bearing PC-3 tumors with clusterin ASO plus paclitaxel or docetaxel paste had reduced mean tumor volume by greater than 50% at 4 weeks. Treatment of mice bearing LNCaP tumors with clusterin ASO plus paclitaxel reduced mean tumor volume and serum PSA level by more than 50% and 70%, respectively. CONCLUSIONS: Complexation of clusterin ASO with chitosan and incorporation into polymeric paste with paclitaxel or docetaxel produced in vitro controlled release of the ASO and in vivo efficacy over 4 weeks following a single intratumoral injection in solid human prostate tumors in mice.
| Efficacy of bioabsorbable antibiotic containing bone screw in the prevention of biomaterial-related infection due to Staphylococcus aureus
Makinen, T. J., M. Veiranto, et al. (2005), Bone 36(2): 292-9.
Abstract: Impregnation of antimicrobial agents within biodegradable orthopedic implants provides a possibility for local antimicrobial prophylaxis of biomaterial-related infections. The objective of this study was to evaluate the efficacy of a bioabsorbable ciprofloxacin containing bone screw (Ab-PLGA) in the prevention of biomaterial-related infection due to Staphylococcus aureus in a rabbit model. Animals in Group I (n=8) received a Ab-PLGA screw contaminated with S. aureus, while animals in Group II (n=8) received a stainless steel (SS) screw contaminated with S. aureus. In two negative control groups, the animals received a Ab-PLGA screw (Group III, n=4) or a SS screw (Group IV, n=4) without bacterial contamination. 18F-FDG-PET imaging, performed at 6 weeks, was applied as a novel quantitative in vivo imaging modality of implant-related infection. Infection was verified by swab cultures, direct cultures of the retrieved implant, and quantitative cultures of pulverized bone. The concentrations of ciprofloxacin in serum and local bone tissue were determined by a high performance liquid chromatographic (HPLC) method with fluorescence (FLD) detection. In the group of contaminated Ab-PLGA screws, all cultures were negative. In the group of contaminated SS screws, all cultures of retrieved implants and six cultures out of eight of pulverized bone were positive for inoculated S. aureus. In negative control groups, all cultures were negative except one contaminant (S. cohnii) found in a SS screw culture. Verified infection of contaminated SS screws was collaborated by the increased 18F-FDG-PET uptake (P=0.004 compared with the group of contaminated Ab-PLGA screws). The mean bone tissue concentration of ciprofloxacin varied from 2.54 to 0.83 microg/g bone as a function of distance from the implantation site. The serum concentration of ciprofloxacin remained undetectable and below the resolution of the analytic method (<5.0 ng/ml). This study confirmed the in vivo efficacy of bioabsorbable antibiotic containing bone screw in the prevention of biomaterial-related infection due to S. aureus.
| Efficacy of ciprofloxacin-releasing bioabsorbable osteoconductive bone defect filler for treatment of experimental osteomyelitis due to Staphylococcus aureus
Koort, J. K., T. J. Makinen, et al. (2005), Antimicrob Agents Chemother 49(4): 1502-8.
Abstract: The concept of local antibiotic delivery via biodegradable bone defect fillers with multifunctional properties for the treatment of bone infections is highly appealing. Fillers can be used to obliterate surgical dead space and to provide targeted local bactericidal concentrations in tissue for extended periods. Eventually, the osteoconductive component of the filler could guide the healing of the bone defect. The present experimental study was carried out to test this concept in a localized Staphylococcus aureus osteomyelitis model in the rabbit (n = 31). A metaphyseal defect of the tibia was filled with a block of bone cement, followed by insertion of a bacterial inoculum. After removal of the bone cement and surgical debridement at 2 weeks, the defect was filled with a ciprofloxacin-containing (7.6% +/- 0.1%, by weight) composite (treated-infection group) or with a composite without antibiotic (sham-treated group). Both a positive control group (untreated-infection group) and a negative control group were also produced. The treatment response, monitored by positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose ([18F]FDG) at 3 and 6 weeks, showed rapidly decreasing amounts of [18F]FDG uptake in the treated-infection group (P = 0.001 compared with the results for the untreated-infection group at 6 weeks). The bacteriological analysis confirmed the eradication of the bone pathogen in the treated-infection group. However, three animals had culture-positive soft tissue infections. All animals in the sham-treated and untreated-infection groups had culture-positive bone infections with typical radiographic changes of osteomyelitis. Histomorphometry, peripheral quantitative computed tomography, and backscattered electron imaging of scanning electron microscopy images verified the osteoconductive properties of the bioactive glass microspheres within the composite. The median bone ciprofloxacin concentrations were 1.2 and 2.1 microg/g at two anatomic locations of the tibia. This is the first report to show the value of [18F]FDG PET for quantitative monitoring of the treatment response in bone infections. The collaborative results of bacteriologic and [18F-FDG] PET studies showed that use of the multifunctional composite was successful for eradication of the S. aureus pathogen from bone.
| Efficacy of photocrosslinkable chitosan hydrogel containing fibroblast growth factor-2 in a rabbit model of chronic myocardial infarction
Fujita, M., M. Ishihara, et al. (2005), J Surg Res 126(1): 27-33.
Abstract: BACKGROUND: Therapeutic angiogenesis in ischemic myocardium has been shown to be an effective strategy to improve regional blood flow and myocardial function. However, no effective delivery system for growth factor administration is yet known to induce important therapeutic angiogenic responses in ischemic myocardium. MATERIALS AND METHODS: FGF-2-incorporated chitosan (FGF-2/chitosan) hydrogels were immobilized on the surface of ischemic myocardium of rabbit models of chronic myocardial infarction by UV-irradiation. After 4 weeks, cardiac functional analyses by noradrenalin challenge and histopathological analyses were performed to evaluate the efficacy of a controlled release of FGF-2 from FGF-2/chitosan hydrogel immobilized on the surface of ischemic myocardium. RESULTS: Significant improvement by application of FGF-2/chitosan hydrogels was found in systolic pressure at the left ventricle, +dp/dt maximum, and -dp/dt maximum during noradrenalin challenge at a dose of 1 microg/kg/min. Histological observations showed that a significantly larger amount of viable myocardium and CD 31 immunostained blood vessels were found in the FGF-2/chitosan hydrogel-applied group than only the chitosan-applied and control groups. CONCLUSIONS: These preliminary results indicate that the controlled release of biologically active FGF-2 molecules from FGF-2/chitosan hydrogel induces angiogenesis and possibly collateral circulation in ischemic myocardium, thereby protecting the myocardium.
| Efficacy of preoperative antimicrobial skin preparation solutions on biofilm bacteria
Paulson, D. S. (2005), Aorn J 81(3): 492-501; quiz 503-6.
Abstract: RESEARCH ON THE MEDICAL EFFICACY of topical antimicrobials and antibiotics against infections has focused largely on the effect on free-floating, planktonic bacteria. IN THE PRESENCE OF nonbiological surfaces (eg, catheters, prosthetic devices, biomaterials), however, bacteria form highly complex biofilm systems that resist traditional medical treatment. BACTERIAL PATHOGENS commonly found in chronic infections in both the planktonic and biofilm state were challenged with a variety of commonly used topical antimicrobial formulations. BIOFILM BACTERIA were shown to be more resistant to killing than planktonic bacteria. Antimicrobial skin preparation times were adequate to significantly reduce bacterial populations protected in biofilms.
| Efficient characterisation of human cell-bioceramic interactions in vitro and in vivo by using enhanced GFP-labelled mesenchymal stem cells
Xia, Z., H. Ye, et al. (2005), Biomaterials 26(29): 5790-800.
Abstract: Human mesenchymal stem cells (hMSCs) were transfected using four retroviral pseudotypes, amphotropic murine leukemia viruses 4070 (MuLV-10A1), a modification of amphotropic pseudotype 4073 (A71G, Q74K, V139M), gibbon ape leukemia virus (GaLV), or feline endogenous virus (RD114) encoding the neomycin resistance (Neo(r)) gene and enhanced green fluorescent protein (eGFP) as genetic markers. It was observed that the MuLV4073 was the most efficient pseudotype for hMSC transfection. The proliferation and differentiation characteristics of eGFP-labelled hMSCs were not significantly different from control hMSCs. G418 selected eGFP-labelled cells were cultured for 3 weeks on two porous, commercially available calcium phosphate bioceramics, a "synthetic hydroxyapatite" and a "deproteinised bone", before implantation into NOD/SCID mice for up to 4 weeks. The eGFP-labelled hMSCs could be readily visualised by their intense green fluorescence both in vitro and in vivo. In "synthetic hydroxyapatite" implants the cells remained in a monolayer, whereas in "deproteinised bone" implants mineralised tissues were detected by histology, scanning electron microscopy and energy dispersive X-ray spectrometry. From the results, it is concluded that the use of eGFP-labelled hMSCs is an effective tool to trace the fate of hMSCs and evaluate the interactions between cells and ceramics both in vitro and in vivo. This is of great value in prospective assessments of these cell populations for use in tissue engineering applications.
| Efficient visible-light-induced photocatalytic disinfection on sulfur-doped nanocrystalline titania
Yu, J. C., W. Ho, et al. (2005), Environ Sci Technol 39(4): 1175-9.
Abstract: Sulfur-doped titanium dioxide exhibits a strong visible-light-induced antibacterial effect. The new photocatalyst can effectively kill Micrococcus lylae, a common Gram-positive bacterium. The relationship between sulfur concentration and the bactericidal activity of S-doped TiO2 was investigated. Results from DMPO spin-trapping electron spin resonance measurements confirm the formation of hydroxyl radicals, which is the origin of the considerable bactericidal activity under visible light irradiation.
| EGF-grafted PDMS surfaces in artificial cornea applications
Klenkler, B. J., M. Griffith, et al. (2005), Biomaterials 26(35): 7286-96.
Abstract: Lack of epithelial cell coverage has remained a persistent problem in the design of an artificial cornea. In this work, polydimethylsiloxane (PDMS) surfaces were modified with epidermal growth factor (EGF) to improve the growth of corneal epithelial cells. The EGF was covalently tethered to PDMS substrates aminated by plasma polymerization of allylamine via a homobifunctional polyethylene glycol (PEG) spacer. Surface modification was confirmed by contact angle and X-ray photoelectron spectroscopy measurements. By varying the ratio of EGF to PEG from 1:50 to 1:5, EGF amounts from 40 to 90 ng/cm2 could be bound, as determined by surface plasmon resonance (SPR) and 125I radiolabelling. Human corneal epithelial cells on the various modified surfaces were cultured both in the presence and absence of EGF in the culture medium to determine the effect of covalently bound EGF on the cells. The results demonstrated that covalently bound EGF on the surfaces is active with respect to promoting epithelial cell coverage. This was significant when compared to unmodified controls.
| Elaboration and "in vitro" characterization of 5-ASA beads
Iruin, A., M. Fernandez-Arevalo, et al. (2005), Drug Dev Ind Pharm 31(2): 231-9.
Abstract: The purpose of this research was to perform the design and in vitro evaluation of alginate beads containing 5-ASA in order to achieve an oral system that protects the drug until it reaches the colon. Alginate beads were prepared by the well-known ionic gelation reaction (Ca2+). The influence of the incorporation of several polymers (Eudragit FS 30D, Eudragit S100, and chitosan) in the initial formulation was studied. In all formulations, entrapment efficiencies of the drug higher than 70% were obtained. The scanning electron microscopy (SEM) study of beads showed homogeneous sizes and shapes in all cases. Finally, the release behavior of these polymeric beads were also studied and compared. The results indicated that Eudragit FS 30D (26%) showed the most favorable dissolution behavior in terms of achieving a controlled release of 5-ASA. To determine the mechanism of drug release from these beads, the Korsmeyer equation was applied. Qt/Qinfinity <0.9 can be described using a Higuchi model and Qt/Qinfinity=0.7 showed a zero-order release period. This formulation was assayed at other different pH values (pH=6; 6.8; 7.2) to assure that there is no release of 5-ASA until the system reaches the colon. No release was observed at pH 6.0. Release was very slow at pH 6.8; averages about 20% an hour at pH 7.2 and was complete within 4 hour at pH 7.4. So, these Eudragit FS beads exhibited interesting dissolution profiles for the therapy of colon pathologies.
Mithieux, S. M. and A. S. Weiss (2005), Adv Protein Chem 70: 437-61.
Abstract: Elastin is a key extracellular matrix protein that is critical to the elasticity and resilience of many vertebrate tissues including large arteries, lung, ligament, tendon, skin, and elastic cartilage. Tropoelastin associates with multiple tropoelastin molecules during the major phase of elastogenesis through coacervation, where this process is directed by the precise patterning of mostly alternating hydrophobic and hydrophilic sequences that dictate intermolecular alignment. Massively crosslinked arrays of tropoelastin (typically in association with microfibrils) contribute to tissue structural integrity and biomechanics through persistent flexibility, allowing for repeated stretch and relaxation cycles that critically depend on hydrated environments. Elastin sequences interact with multiple proteins found in or colocalized with microfibrils, and bind to elastogenic cell surface receptors. Knowledge of the major stages in elastin assembly has facilitated the construction of in vitro models of elastogenesis, leading to the identification of precise molecular regions that are critical to elastin-based protein interactions.
| Elastin as a self-organizing biomaterial: use of recombinantly expressed human elastin polypeptides as a model for investigations of structure and self-assembly of elastin
Keeley, F. W., C. M. Bellingham, et al. (2002), Philos Trans R Soc Lond B Biol Sci 357(1418): 185-9.
Abstract: Elastin is the major extracellular matrix protein of large arteries such as the aorta, imparting characteristics of extensibility and elastic recoil. Once laid down in tissues, polymeric elastin is not subject to turnover, but is able to sustain its mechanical resilience through thousands of millions of cycles of extension and recoil. Elastin consists of ca. 36 domains with alternating hydrophobic and cross-linking characteristics. It has been suggested that these hydrophobic domains, predominantly containing glycine, proline, leucine and valine, often occurring in tandemly repeated sequences, are responsible for the ability of elastin to align monomeric chains for covalent cross-linking. We have shown that small, recombinantly expressed polypeptides based on sequences of human elastin contain sufficient information to self-organize into fibrillar structures and promote the formation of lysine-derived cross-links. These cross-linked polypeptides can also be fabricated into membrane structures that have solubility and mechanical properties reminiscent of native insoluble elastin. Understanding the basis of the self-organizational ability of elastin-based polypeptides may provide important clues for the general design of self-assembling biomaterials.
| Elastomeric flexible free-standing hydrogen-bonded nanoscale assemblies
Lutkenhaus, J. L., K. D. Hrabak, et al. (2005), J Am Chem Soc 127(49): 17228-34.
Abstract: Poly(ethylene oxide) (PEO) is a key material in solid polymer electrolytes, biomaterials, drug delivery devices, and sensors. Through the use of hydrogen bonds, layer-by-layer (LBL) assemblies allow for the incorporation of PEO in a controllable tunable thin film, but little is known about the bulk properties of LBL thin films because they are often tightly bound to the substrate of assembly. The construction technique involves alternately exposing a substrate to a hydrogen-bond-donating polymer (poly(acrylic acid)) and a hydrogen-bond-accepting polymer (PEO) in solution, producing mechanically stable interdigitated layers of PEO and poly(acrylic acid) (PAA). Here, we introduce a new method of LBL film isolation using low-energy surfaces that facilitate the removal of substantial mass and area of the film, allowing, for the first time, the thermal and mechanical characterization that was previously difficult or impossible to perform. To further understand the morphology of the nanoscale blend, the glass transition is measured as a function of assembly pH via differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The resulting trends give clues as to how the morphology and composition of a hydrogen-bonded composite film evolve as a function of pH. We also demonstrate that LBL films of PEO and PAA behave as flexible elastomeric blends at ambient conditions and allow for nanoscale control of thickness and film composition. Furthermore, we show that the crystallization of PEO is fully suppressed in these composite assemblies, a fact that proves advantageous for applications such as ultrathin hydrogels, membranes, and solid-state polymer electrolytes.
| Elastomeric hydrolyzable porous scaffolds: copolymers of aliphatic polyesters and a polyether-ester
Odelius, K., P. Plikk, et al. (2005), Biomacromolecules 6(5): 2718-25.
Abstract: Porous scaffolds of 1,5-dioxepan-2-one (DXO), L-lactide (LLA), and epsilon-caprolactone (CL) were prepared by a solvent casting, salt particulate leaching technique in which the composites were detached from their mold using a novel methanol swelling procedure. By incorporating DXO segments into polymers containing LLA or CL, an increase in hydrophilicity is achieved, and incorporating soft amorphous domains in the crystalline sections enables tailoring of the mechanical properties. The porosities of the scaffolds ranged from 89.2% to 94.6%, and the pores were shown to be interconnected. The materials were synthesized by bulk copolymerization of 1,5-dioxepan-2-one (DXO), L-lactide (LLA), and epsilon-caprolactone (CL) using stannous 2-ethylhexanoate as catalyst. The copolymers formed varied in structure; poly(DXO-co-CL) is random in its arrangement, whereas poly(DXO-co-LLA) and poly(LLA-co-CL) are more blocky in their structures.
| Electric block current induced detachment from surgical stainless steel and decreased viability of Staphylococcus epidermidis
van der Borden, A. J., H. C. van der Mei, et al. (2005), Biomaterials 26(33): 6731-5.
Abstract: In vitro studies investigating the influence of electric DC current on bacterial detachment have demonstrated that continuous currents of only 25-125 microA stimulated staphylococcal strains to detach from surgical stainless steel. However, DC currents produce more power that has to be dissipated by the skin as compared to alternating currents. Also, an excess of ions on the steel can cause negative osteogenesis and fixation results. Therefore, it is the aim of this paper to examine whether detachment of Staphylococcus epidermidis from stainless steel surfaces in a parallel plate flow chamber can also be stimulated using electric block currents. Block currents of 15, 60 and 100 microA with different frequencies (0.1-2 Hz) and duty cycles (5-50%) were applied to induce bacterial detachment. Block currents of 100 microA cause detachment of about 76% of adhering staphylococci from stainless steel, whereas in addition the remaining bacteria are less viable, as determined by culturing the remaining bacteria on agar plates. Therewith, block current-induced detachment of adhering bacteria from stainless steel appears to be an equally promising method to prevent infection of orthopaedic fixation pins and screws than application of DC currents.
| Electrical docking of microtubules for kinesin-driven motility in nanostructures
van den Heuvel, M. G., C. T. Butcher, et al. (2005), Nano Lett 5(2): 235-41.
Abstract: We demonstrate localized electrical control of the docking of microtubules onto engineered kinesin-coated structures. After applying a voltage to a gold electrode, we observe an enhanced transport of microtubules from solution toward the surface and a subsequent increase of the amount of moving microtubule shuttles. Switching off the voltage leads to a partial detachment of microtubules from the surface. The surface coverage of microtubules, during both the docking and undocking events, follows an exponential time dependence. We provide a simple kinetic model, incorporating the equilibrium between free and surface-bound microtubules, that explains these data.
| Electrical polarization of plasma-spray-hydroxyapatite coatings for improvement of osteoconduction of implants
Kato, R., S. Nakamura, et al. (2005), J Biomed Mater Res A 74(4): 652-8.
Abstract: We have established the electrical polarization method of hydroxyapatite (HA) coatings (HAC) for clinical use, such as dental and orthopedic implants. The HAC examined in the current study was prepared in titanium substrates by plasma spraying of beta-tricalcium phosphate (TCP) powders followed by hydrothermal treatment. The prepared HAC consisted of a single phase of HA, because the starting TCP phase was completely transformed to the HA phase during the posthydrothermal treatment. Polarization was carried out at the elevated temperature of 400 degrees C under a d.c. field of 1 kV. cm(-1). The electrical measurements showed that the stored charges of the polarized HAC were greater than the reported value of the sintered ceramic HA. The enhanced bioactivity of the polarized HAC was demonstrated using 1.5 simulated body fluid (SBF). The crystal growth from the SBF solution was accelerated on the negatively charged surface in comparison with the untreated HAC. Similar to the polarized ceramic HA, the current results confirmed that the bioactivity of HAC would be effective for improving the initial fixation by polarization.
| Electrical stimulation alters protein adsorption and nerve cell interactions with electrically conducting biomaterials
Kotwal, A. and C. E. Schmidt (2001), Biomaterials 22(10): 1055-64.
Abstract: Electrical charges have been shown to enhance nerve regeneration; however, the mechanisms for this effect are unclear. One hypothesis is that an electrical stimulus alters the local electrical fields of extracellular matrix molecules, changing protein adsorption. We have investigated this hypothesis--that electrical stimulation increases the adsorption of serum proteins, specifically fibronectin (FN), to the electrically conducting polymer polypyrrole (PP), thereby, increasing neurite extension. PP was used because electrical stimulation of PP has been shown to significantly enhance neurite outgrowth, and more importantly, PP can be formed into conduits to guide nerve regeneration in vivo. Here, we looked at the effects of electrical stimulation on protein adsorption when an electrical current was applied to PP (1) during protein adsorption (immediate stimulation) and (2) several hours after protein adsorption (delayed stimulation). We found that immediate stimulation of PP increases FN adsorption from purified FN and serum-containing solutions. Correspondingly, PC-12 cells grown on PP films that had been previously adsorbed with FN during immediate stimulation expressed longer neurites. However, for delayed stimulation, no significant differences in adsorption or neurite outgrowth were observed. These studies suggest that increased FN adsorption with immediate electrical stimulation may explain enhanced neurite extension on electrically stimulated PP.
| Electrochemical and XPS studies of titanium for biomaterial applications with respect to the effect of hydrogen peroxide
Pan, J., D. Thierry, et al. (1994), J Biomed Mater Res 28(1): 113-22.
Abstract: Electrochemical measurements, x-ray photoelectron spectroscopy, and scanning tunneling microscopy have been used to study the effect of hydrogen peroxide on the passivity of titanium in a phosphate-buffered saline (PBS) solution. The results indicate that the passive film formed in the PBS solution--with and without addition of H2O2--may be described with a two-layer structure model. The inner layer has a structure close to TiO2 whereas the outer layer consists of hydroxylated compounds. The introduction of H2O2 in the PBS solution broadens the hydroxylate-rich region, probably due to the formation of a Ti(IV)-H2O2 complex. Furthermore, the presence of H2O2 results in enhanced dissolution of titanium and a rougher surface on a microscopic scale. Finally, a dark pigmentation (blue color) is observed when titanium has been exposed--for several weeks--to PBS with additions of H2O2.
| Electrochemical biosensing based on universal affinity biocomposite platforms
Zacco, E., M. I. Pividori, et al. (2006), Biosens Bioelectron 21(7): 1291-301.
Abstract: Rigid conducting biocomposites are versatile and effective transducing materials for the construction of a wide range of amperometric biosensors such as immunosensors, genosensors and enzymosensors, particularly if the transducer is bulk-modified with universal affinity biomolecules. The strept(avidin)-graphite-epoxy biocomposite could be considered as an universal immobilization platform whereon biotinylated DNAs, oligonucleotides, enzymes or antibodies can be captured by means of the highly affinity (strept)avidin-biotin reaction. Universal affinity biocomposite-based biosensors offer many potential advantages compared to more traditional electrochemical biosensors commonly based on a biologically surface-modified transducer. The integration of many materials into one matrix is their main advantage. As biological bulk-modified materials, the conducting biocomposites act not only as transducers, but also as reservoir for the biomaterial. After its use, the electrode surface can be renewed by a simple polishing procedure, establishing a clear advantage of these approaches relative to classical biosensors and other common biological assays. Moreover, the same material is useful for the analysis of many molecules whose determinations are based on genetic, enzymatic or immunological reactions. The different strategies for electrochemical genosensing, immunosensing and enzymosensing, all of them being dependent on the presence of a redox enzyme marker for the generation of the electrochemical signal, based on this universal affinity biocomposite platform are all presented and discussed.
| Electrochemical characterisation of dental alloys: its possibilities and limitations
Mueller, W. D., C. Schoepf, et al. (2005), Anal Bioanal Chem 381(8): 1520-5.
Abstract: Dental alloys are metallic biomaterials which have a broad variation of composition compared to technical alloys. It is therefore in the interest of patients and technicians to conduct a good assessment of the electrochemical behaviour of dental alloys in order to collect information about their corrosion resistance. The purpose of this work was to demonstrate possibilities and limitations of two electrochemical techniques: the voltammetry of immobilised microparticles (ViMP) onto lead, and cyclic voltammetry measurements with the help of the mini-cell system (MCS). Based on fingerprints obtained from ViMP it was possible to analyse and differentiate the dental alloys. The results obtained by MCS were comparable with ViMP, but give a better understanding of the corrosion behaviour of the materials.
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