Antibiotic release from F-doped nanotubular oxide layer on TI6AL4V alloy to decrease bacterial viability

We aimed to evaluate the release of two antibiotics: gentamicin and vancomycin loaded into F-doped nanotubular anodic oxide layers, as well as their bactericide effect. F-doped nanotubular oxide layers fabricated on Ti-6Al-4V loaded with gentamicin (Gm), vancomycin (Vm) and their mixture (Gm?+?Vm) by a previously described loading method. Antibiotic release was studied by RP-HPLC and by a biological method. Bactericidal activity was evaluated by a bacterial adherence protocol described previously using on three clinically important bacterial species. The antibiotic release steady up to 120 and 180?min for Gm and Vm, respectively, and despite the antibiotic concentration decreased, their biological activity was maintained over time. The number of living bacteria of three species tested on NT-Gm specimens was significantly lower than on NT specimens without antibiotics (P?<?0.01). There are significant differences among NT-Gm and NT-Gm?+?Vm specimens (P?<?0.05) for S. aureus 15981, S. epidermidis ATCC 35984, and P. aeruginosa ATCC 27853 and no differences between NT-Vm and NT-Gm?+?Vm for staphylococci (P?>?0.05). In conclusion, this Gm?+?Vm loading method added to the properties of F-doped nanotubular oxide layers fabricated on Ti-6Al-4V, and therefore surfaces with antibacterial, biocompatible, tissue integration stimulating and spread-spectrum bactericidal properties can be obtained.

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Fabrication of enzyme-responsive composite coating for the design of antibacterial surface

In this study, a type of bacteria enzyme-triggered antibacterial surface with a controlled release of Ag ions was developed. Firstly, chitosan-silver nanocomposites (Chi@Ag NPs) were in situ synthesized via using ascorbic acid as reducing agent. Chi@Ag NPs were characterized by transmission electron microscopy, ultraviolet–visible spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Subsequently, Chi@Ag NPs and hyaluronic acid (HA) were used to fabricate antibacterial composite coating via Layer-by-Layer (LBL) self-assembly method. The successful construction of Chi@Ag NPs/HA composite coating was confirmed by scanning electron microscopy, energy dispersive spectroscopy and contact angle measurements, respectively. Then, the amount of released Ag ion was analyzed by inductively coupled plasma atomic emission spectrometry, which demonstrated that the release of Ag ions from the surface could be triggered by enzyme (e.g. hyaluronidase). A series of antibacterial tests in vitro, including zone of inhibition test, bacterial viability assay, antibacterial rate measurement and bacteria adhesion observation, demonstrated that the enzyme-responsive surface could inhibit the growth of bacteria. On the whole, this study provides an alternative approach for the fabrication of antibacterial surfaces on synthetic materials in various fields with the minimal side effects on surrounding environment and human body.

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Human amniotic membrane for guided bone regeneration of calvarial defects in mice

Due to its biological properties, human amniotic membrane (hAM) is widely studied in the field of tissue engineering and regenerative medicine. hAM is already very attractive for wound healing and it may be helpful as a support for bone regeneration. However, few studies assessed its potential for guided bone regeneration (GBR). The purpose of the present study was to assess the potential of the hAM as a membrane for GBR. In vitro, cell viability in fresh and cryopreserved hAM was assessed. In vivo, we evaluated the impact of fresh versus cryopreserved hAM, using both the epithelial or the mesenchymal layer facing the defect, on bone regeneration in a critical calvarial bone defect in mice. Then, the efficacy of cryopreserved hAM associated with a bone substitute was compared to a collagen membrane currently used for GBR. In vitro, no statistical difference was observed between the conditions concerning cell viability. Without graft material, cryopreserved hAM induced more bone formation when the mesenchymal layer covered the defect compared to the defect left empty. When associated with a bone substitute, such improved bone repair was not observed. These preliminary results suggest that cryopreserved hAM has a limited potential for GBR.

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Approaches to improve integration and regeneration of an <Emphasis Type="Italic">ex vivo</Emphasis> derived temporomandibular joint disc scaffold with variable matrix composition

Due to their natural biochemical and biomechanical characteristics, using ex vivo tissues as platforms for guided tissue regeneration has become widely accepted, however subsequent attachment and integration of these constructs in vivo is often overlooked. A decellularized porcine temporomandibular joint (TMJ) disc has shown promise as a scaffold to guide disc regeneration and preliminary work has shown the efficacy of surfactant (SDS) treatment within the fibrocartilaginous disc to remove cellular components. The majority of studies focus on the intermediate region of the disc (or disc proper). Using this approach, inherent attachment tissues can be maintained to improve construct stability and integration within the joint. Unlike human disc attachment tissue, the porcine attachment tissues have high lipid content which would require a different processing approach to remove immunogenic components. In order to examine the effect of delipidation on the attachment tissue properties, SDS and two organic solvent mixtures (acetone/ethanol and chloroform/methanol) were compared. Lipid and cellular solubilization, ECM alteration, and seeded human mesenchymal stem cell (MSC) morphology and viability were assessed. Quantitative analysis showed SDS treatments did not effectively delipidate the attachment tissues and cytotoxicity was noted toward MSC in these regions. Acetone/ethanol removed cellular material but not all lipids, while chloroform/methanol removed all visible lipid deposits but residual porcine cells were observed in histological sections. When a combination of approaches was used, no residual lipid or cytotoxicity was noted. Preparing a whole TMJ graft with a combined approach has the potential to improve disc integration within the native joint environment.

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Properties of collagen-based hemostatic patch compared to oxidized cellulose-based patch

Two self-adhering hemostatic patches, based on either PEG-coated collagen (PCC) or PEG-coated oxidized cellulose (PCOC), are compared regarding to maximum burst pressure, mechanical stability, and swelling. In addition, the induction of tissue adhesions by the materials was assessed in a rabbit liver abrasion model. Both materials showed comparable sealing efficacy in a burst pressure test (37?±?16 vs. 35?±?8?mmHg, P?=?0.730). After incubation in human plasma, PCC retained its mechanical properties over the test period of 8?h, while PCOC showed faster degradation after the 2?h time-point. The degradation led to a significantly decreased force at break (minimum force at break 0.55?N during 8?h for PCC, 0.27?N for PCOC; p?<?0.001). Further, PCC allowed significantly higher deformation before break (52% after 4?h and 50% after 8?h for PCC, 18% after 4?h and 23% after 8?h for PCOC; p?=?0.003 and p?<?0.001 for 4?h and 8?h, respectively) and showed less swelling in human plasma (maximum increase in thickness: ~20% PCC, ~100% PCOC). Faster degradation of PCOC was visible macroscopically and histologically in vivo after 14 days. PCC showed visible structural residues with little cellular infiltration while strong infiltration with no remaining structural material was seen with PCOC. In vivo, a higher incidence of adhesion formation after PCOC application was detected. In conclusion, PCC has more reliable mechanical properties, reduced swelling, and less adhesion formation than PCOC. PCC may offer greater clinical benefit for surgeons in procedures that have potential risk for body fluid leakage or that require prolonged mechanical stability.

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Electrospun polyvinyl alcohol membranes incorporated with green synthesized silver nanoparticles for wound dressing applications

Electrospun membranes have the potential to act as an effective barrier for wounds from the external environment to prevent pathogens. In addition, materials with good antibacterial properties can effectively fight off the invading pathogens. In this paper, we report the development of a novel electrospun polyvinyl alcohol (PVA) membrane containing biosynthesized silver nanoparticle (bAg) for wound dressing applications. Plant extract from a medicinal plant Mimosa pudica was utilized for the synthesis of bAg. Synthesized bAg were characterized by Ultraviolet-Visible (UV) Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The morphology of bAg was obtained from Transmission Electron Microscopy (TEM) and found that they were spherical in morphology with average particle size 7.63?±?1.2?nm. bAg nanoparticles incorporated PVA membranes were characterized using several physicochemical techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD) analysis. Experimental results confirmed the successful incorporation of bAg in PVA fibers. PVA nanofiber membranes incorporated with bAg showed good mechanical strength, excellent exudate uptake capacity, antibacterial activity, blood compatibility and cytocompatibility.

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Novel resin-based dental material with anti-biofilm activity and improved mechanical property by incorporating hydrophilic cationic copolymer functionalized nanodiamond

There is an increasing clinical need to design dental restorative materials that combine excellent mechanical property and anti-biofilm activity. In the current study, photocurable polycation functionalized nanodiamond (QND) was synthesized and proposed as novel filler for dental resins. By reason of increased repulsive force between nanoparticles and enhanced compatibility with resin matrix, QND dispersed uniformly in reinforced resins, which would help to transfer stress and deformation from the matrix to fillers more efficiently, resulting in a significant improvement in mechanical properties. Notably, the Vickers’s hardness, flexural strength and flexural modulus of resins containing 1.0?wt% QND were 44.5, 36.1 and 41.3% higher than that of control, respectively. The antibacterial activity against Streptococcus mutans (S. mutans) showed that QND-incorporated resins produced anti-adhesive property due to their hydrophilic surfaces and could suppress bacterial growth as a result of the contact-killing effect of embedded nanocomposites. As the synergistic effect of anti-adhesive and bactericidal performance, resins loading 1.0~1.5?wt% QNDs displayed excellent anti-biofilm activity. Meanwhile, the results of macrophage cytotoxicity showed that the proliferation of RAW 264.7 cells remained 84.3%, even at a concentration of 1.0?wt% QNDs after 7-day incubation. Therefore, the QND-containing dental resin with the combination of high mechanical property, bacteria-repellent capability and antibacterial performance holds great potential as a restorative material based on this scheme.

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Ultraviolet photofunctionalization of nanostructured titanium surfaces enhances thrombogenicity and platelet response

The purpose of this study was to evaluate blood and platelet response to nanostructured TiO₂ coatings and to investigate the effect of Ultraviolet (UV) light treatment on blood clotting ability, platelet activation and protein adhesion. Ti-6Al-4V titanium alloy plates (n?=?138) were divided into three groups; a sol–gel derived MetAlive^TM coating (MA); hydrothermal coating (HT); and a non-coated group (NC). Sixty nine titanium substrates were further treated with UV light for 1?h. The thrombogenicity of the titanium substrates was assessed using fresh human blood with a whole blood kinetic clotting time method. The platelet adhesion test was conducted to evaluate the morphology and adhesion behavior of the platelets on the titanium substrates. Human diluted plasma and bovine fibronectin were used to evaluate protein adsorption. Total clotting time for the UV treated HT, MA and NC titanium substrates was almost 40?min compared to 60?min for non-UV substrates, the total clotting time for the UV treated groups were significantly lower than that of the non UV NC group (p?<?0.05). UV light treatment had significantly enhanced coagulation rates. The HT and MA substrates presented more platelet aggregation, spreading and pseudopod formation in comparison with the NC substrates. UV treatment did not affect the platelet activation and protein adsorption. This in vitro study concluded that nanostructured titanium dioxide implant surfaces obtained by sol–gel and hydrothermal coating methods increased coagulation rates and enhanced platelet response when compared with non-coated surfaces. UV light treatment clearly improved thrombogenicity of all examined Ti-6Al-4V surfaces.

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Molecular mechanisms driving <Emphasis Type="Italic">Streptococcus mitis</Emphasis> entry into human gingival fibroblasts in presence of chitlac-nAg and saliva

The molecular mechanisms leading to Streptococcus mitis capability of entering oral cells were investigated in a co-culture of S. mitis and Human Gingival Fibroblasts (HGFs) in the presence of saliva. An innovative colloidal solution based on silver nanoparticles (Chitlac-nAg), a promising device for daily oral care, was added to the experimental system in order to study the effects of silver on the bacterial overgrowth and ability to enter non-phagocytic eukaryotic cells. The entry of bacteria into the eukaryotic cells is mediated by a signalling pathway involving FAK, integrin β1, and the two cytoskeleton proteins vinculin and F-actin, and down-regulated by the presence of saliva both at 3 and 48?h of culture, whereas Chitlac-n Ag exposure seems to influence, by incrementing it, the number of bacteria entering the fibroblasts only at 48?h. The formation of fibrillary extrusion from HGFs and the co-localization of bacteria and silver nanoparticles within the fibroblast vacuoles were also recorded. After longer experimental times (72 and 96?h), the number of S. mitis chains inside gingival cells is reduced, mainly in presence of saliva. The results suggest an escape of bacteria from fibroblasts to restore the microbial balance of the oral cavity.

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Self-assembled nanoparticles for cellular delivery of peptide nucleic acid using amphiphilic N,N,N-trimethyl-O-alkyl chitosan derivatives

Peptide nucleic acid (PNA) holds enormous potentials as antisense/antigenic drug due to its specific binding ability and biostability with DNA or RNA. However, the poor cellular delivery is the key obstacle in development of PNA therapy. To overcome this difficulty, we developed self-assembled nanoparticles (NPs) for delivery of PNA to living cells using amphiphilic CS derivatives. A series of N,N,N-trimethyl-O-alkyl chitosans (TMACs) with different lengths of alkyl chains were synthesized. The structures of these synthesized chemicals were characterized with FT-IR and ¹H NMR. We found that the TMACs were all able to self-assemble in aqueous condition to form nano-size NPs. These nano-size NPs are spherical shape with a size range of around 100?nm and a zeta potential above +30?mV. PNA was easily encapsulated into chitosan derivative NPs by an ultrasonic method with entrapment efficiency up to 75%. The PNA-loaded TMAC NPs released the drug in a sustained manner in PBS (pH 7.4) at 37?°C. N,N,N-trimethyl-O-cetyl chitosan (TMCC) showed the best in vitro hemocompatibility and cell viability. These TMCC based NPs were able to dramatically increase the cellular uptake of PNA, specifically, 66-fold higher compared to without using these nanoparticles. The results suggest that the designed TMCC NPs might be a promising solution for improving cellular delivery of PNA.

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Osteoblastic cell response on high-rough titanium coatings by cold spray

Highly rough and porous commercially pure titanium coatings have been directly produced for first time by the cold spray technology, which is a promising technology in front of the vacuum plasma spray for oxygen sensitive materials. The wettability properties as well as the biocompatibility evaluation have been compared to a simply sand blasted Ti6Al4V alloy substrate. Surface topographies were analysed using confocal microscopy. Next, osteoblast morphology (Phalloidin staining), proliferation (MTS assay), and differentiation (alkaline phosphatase activity) were examined along 1, 7 and 14 days of cell culture on the different surfaces. Finally, mineralization by alizarin red staining was quantified at 28 days of cell culture. The contact angle values showed an increased hydrophilic behaviour on the as-sprayed surface with a good correlation to the biological response. A higher cell viability, proliferation and differentiation were obtained for highly rough commercial pure titanium coatings in comparison with sand blasted substrates. Cell morphology was similar in all coatings tested; at 14 days both samples showed extended filopodia. A higher amount of calcium-rich deposits was detected on highly rough surfaces. In summary, in-vitro results showed an increase of biological properties when surface roughness increases.

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Glucose-installed biodegradable polymeric micelles for cancer-targeted drug delivery system: synthesis,characterization and <Emphasis Type="Italic">in vitro</Emphasis> evaluation

Glucose metabolism of cancer can be used as a strategy to target cancer cells which exhibit altered glycolytic rate. The facilitated glucose transporter (Glut) plays an important role in enhancement glycolytic rate resulting in increased glucose uptake into cancer cells. ¹⁸FGD-PET image is an example for using Glut as a targeting to diagnose the high glycolytic rate of tumor. Thus, Glut may be adapted to target cancer cells for drug delivery system. Herein, biodegradation polymeric micelles target cancer cells by Glut was fabricated. The amphiphilic block copolymer of poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL) was synthesized where terminal group of the PEG chain was installed with glucose molecules. The ¹H-NMR confirmed the existence of glucose moiety from two distinct peaks (5.2 and 4.7 ppm) of protons at anomeric carbon of glucose. Glucose-PEG-b-PCL spontaneously forms micelles in an aqueous solution. The size and zeta potential were 22?nm and -7 mv, respectively. Glucose-micelles have high stability, and no evidence of cytotoxicity was found after incubation for 7 days. Doxorubicin, used as a fluorescent probe, was loaded into glucose-micelles. The enhanced amount of doxorubicin as a result of glucose-micelles in PC-3, MCF-7 and HepG2 was evaluated by fluorescence microscopy and flow cytometer. Glucose molecules on the surface of micelles increased internalization and enhanced uptake of micelles via bypassing endocytosis pathway. These results show the use of glucose as a targeting ligand on the micelle surface to target cancer cells via Glut.

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Electrospinning of zein/propolis nanofibers; antimicrobial properties and morphology investigation

In this work, for the first time, zein nanofiber mats loaded with ethanol extracts propolis (EEP) were successfully produced. Raw propolis was extracted by ethanol 70% and total flavonoid content was estimated by aluminum chloride colorimetric method. The anti-microbial activity of the EEP was investigated and compared with amoxicillin via zone of inhibition test against various microorganisms included gram-positive: Staphylococcus aureus, Staphylococcus epidermidis, gram-negative: Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa and fungus: Candida albicans. The EEP showed activity only against gram-positive types and fungus, whereas no activity was observed against gram-negative types. Electrospun zein nanofiber was obtained from 70% ethanolic solutions included different content of zein, 15–40?wt.%. The SEM images revealed a smooth ribbon-like morphology for zein nanofibers without any beads in zein content more than 25?wt.%. As well, the SEM images of electrospun zein nanofibers containing different content of propolis (0–40?wt.% based on the zein content) disclosed the increase in the average size of fibers with propolis content from 264 to 419?nm. This increasing was more probably due to the reduction in ionic conductivity of zein solutions with propolis content. The proteinic nature of zein along with the antimicrobial activity and the herbal nature of the propolis make the obtained mats promising candidate for more evaluation in wound healing study.

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PolyNaSS grafting on titanium surfaces enhances osteoblast differentiation and inhibits <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> adhesion

Titanium surface modifications to simultaneously prevent bacterial adhesion but promote bone-cell functions could be highly beneficial for improving implant osseointegration. In the present in vitro study, the effect of sulfonate groups on titanium surfaces was investigated with respect to both S. aureus adhesion and osteoblast functions pertinent to new bone formation. Commercial pure titanium (cpTi) squares were oxydized (Tiox), grafted with poly(sodium styrene sulfonate) groups (Tigraft) by covalent bonding using radical polymerization, and were characterized by infrared spectroscopy (HATR-FTIR) and colorimetry. Bacterial adhesion study showed that Tigraft exhibited high inhibition of S. aureus adhesion S at levels >90 %, when compared to cpTi (P < 0.05). In contrast osteoblasts adhesion was similar on all three titanium surfaces. While the kinetics of cell proliferation were similar on the three titanium surfaces, Alkaline phosphatase-specific activity of osteoblasts cultured on Tigraft surfaces was twofold higher than that observed on either on Tiox or cpTi surfaces (P < 0.01). More importantly, the amount and the distribution of calcium-containing nodules was different. The total area covered by calcium-containing nodules was 2.2-fold higher on the Tigraft as compared to either Tiox or cpTi surfaces (P < 0.01). These results provide evidence that poly(sodium styrene sulfonate) groups grafting on cpTi simultaneously inhibits bacteria adhesion but promote osteoblast function pertinent to new bone formation. Such modified titanium surfaces offer a promising strategy for preventing biofilm-related infections and enhancing osteointegration of implants in orthopaedic and dental applications.     

HRP-mediated graft polymerization of acrylic acid onto silk fibroins and <Emphasis Type="Italic">in situ</Emphasis> biomimetic mineralization

Silk fibroin (SF) can be extensively utilized in biomedical areas owing to its appreciable bioactivity. In this study, biocompatible composites of SF and hydroxyapatite (HAp) were fabricated through in situ biomimetic mineralization process. Graft copolymerization of acrylic acid (AA) onto SF was conducted by using the catalytic system of acetylacetone (ACAC), hydrogen peroxide (H₂O₂) and horseradish peroxidase (HRP), for enhancing the deposition of apatite onto the fibroin chains. Subsequently, biomimetic mineralization of the prepared fibroin-based membrane was performed in Ca/P solutions to synthesize the organized SF/HAp composites. The efficacies of graft copolymerization and biomimetic mineralization were evaluated by means of ATR-FTIR, GPC, EDS-Mapping, XRD and others. The results denoted that AA was successfully graft-copolymerized with fibroin and formed the copolymer of silk fibroin-graft-polyacrylic acid (SF-g-PAA), and the grafting percentage (GP) and grafting efficiency (GE) under the optimal condition reached to 23.2% and 29.4%, respectively. More mineral phases were detected on the surface of SF-g-PAA membrane after mineralization process when compared to that of the untreated fibroin membrane, companying with an improved mechanical property. According to MG-63 cell viability and fluorescent adhesion assays, the mineralized SF-g-PAA composite showed satisfactory biocompatibility and exceptional adhesive effects as well. The synthetized composite of SF-g-PAA/HAp can be potentially applied in the fields of bone tissue engineering.

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Poly(amidoamine)-alginate hydrogels: directing the behavior of mesenchymal stem cells with charged hydrogel surfaces

The surface charge of a biomaterial represents a promising tool to direct cellular behavior, which is crucial for therapeutic approaches in regenerative medicine. To expand the understanding of how the material surface charge affects protein adsorption and mesenchymal stem cell behavior, differently charged surfaces with zeta potentials spanning from ?25?mV to +15?mV were fabricated by the conjugation of poly(amidoamine) to alginate-based hydrogels. We showed that the increase of the biomaterials surface charge resulted in enhanced quantities of biologically available, surface-attached proteins. Since different surface charges were equalized after protein adsorption, mesenchymal stem cells interacted rather with diverse protein compositions instead of different surface features. Besides an enhanced cell attachment to increasingly positively charged surfaces, the cell spreading area and the expression of adhesion-related genes integrin α5 and tensin 1 were found to be increased after adhesion. Moreover, first results indicate a potential impact of the surface charge on mesenchymal stem cell differentiation towards bone and fat cells. The improved understanding of surface charge-related cell behavior has significant impact on the design of biomedical devices and artificial organs.

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A combined approach for the development of novel sutures with antibacterial and regenerative properties: the role of silver and silk sericin functionalization

Chronic wounds and related infections cause physical and psychological distress in patients, increased mortality, disability and high health care costs. The healing process can be delayed by several factors and in particular by the risk of infections, which can be further complicated by the increasing number of antibiotic-resistant microorganisms. New approaches in wounds management have been encouraged, aiming at preventing infections and improving wound healing. In this scenario, silver has emerged as an ideal antimicrobial agent due to its recognized efficacy against bacteria, viruses and fungi. Moreover, silk and in particular silk sericin from Bombyx mori has demonstrated excellent biological properties and can be considered a good candidate for skin tissue engineering. In this study absorbable PLGA sutures were functionalized with silk sericin and, then, they were treated with silver through an in situ photochemical deposition technology in order to develop an antibacterial and regenerative biomedical device. Morphological analysis was performed by Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM-EDX) in order to evaluate the presence and distribution of silver deposited on the sutures. The stability and durability of the sericin/silver coatings were tested and the results were related to both antibacterial properties and sample degradation. The biological analyses also aimed at studying the biocompatibility and wound healing properties of the device, evaluating the synergistic effect between sericin and silver.

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Hybrid <Superscript>99m</Superscript>Tc-magnetite tracer for dual modality sentinel lymph node mapping

Accuracy of sentinel lymph node identification using radioactive tracers in non-superficial cancers can be limited by radiation shine through and low spatial resolution of detection systems such as intraoperative gamma probes. By utilising a dual radioactive/magnetic tracer, sensitive lymphoscintigraphy can be paired with high spatial resolution intraoperative magnetometer probes to improve the accuracy of sentinel node detection in cancers with complex multidirectional lymphatic drainage. Dextran-coated magnetite nanoparticles (33?nm mean hydrodynamic diameter) were labelled with ^99mTc and applied as a lymphotropic tracer in small and large animal models. The dual tracer could be radiolabelled with 98?±?2% efficiency after 10?min of incubation at room temperature. Biodistribution studies of the tracer were conducted in normal rats (subdermal and intravenous tail delivery, n?=?3) and swine (subdermal hind limb delivery, n?=?5). In rats the dual tracer migrated through four tiers of lymph node, 20?min after subdermal injection. Results from intravenous biodistribution test for radiocolloids demonstrated no aggregation in vivo, however indicated the presence of some lower-molecular weight radioactive impurities (^99mTc-dextran). In swine, the dual tracer could be effectively used to map lymphatic drainage from hind hoof to popliteal and inguinal basins using intraoperative gamma and magnetometer probes. Of the eight primary nodes excised, eight were positively identified by gamma probe and seven by magnetometer probe. The high-purity dual tracer shows early promise for sentinel node identification in complex lymphatic environments by combining sensitive preoperative lymphoscintigraphy with a high-resolution intraoperative magnetometer probe.

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Synthesis of bio-inspired Ag–Au nanocomposite and its anti-biofilm efficacy

In the present study, bio-inspired Ag–Au nanocomposite was synthesized using banana peel extract (BPE) powder. The Ag–Au nanocomposite was characterized using various techniques such as UV–vis spectrophotometry, transmission electron microscopy (TEM) attached with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Efficiency of AuNPs, AgNPs and Ag–Au nanocomposite was tested for their antibacterial activity against Pseudomonas aeruginosa NCIM 2948. The Ag–Au nanocomposite exhibits enhanced antimicrobial activity over its monometallic counterparts. Anti-biofilm activity of AgNPs, AuNPs and Ag–Au nanocomposite against P. aeruginosa was evaluated on glass surfaces. The Ag–Au nanocomposite exhibited the highest biofilm reduction (70–80%) when compared with individual AgNPs and AuNPs. Effect of AuNPs, AgNPs and Ag–Au nanocomposite on biofilm formation was evaluated in 96 wells microtiter plates. The percentage of biofilm inhibition was sharply increased with increasing concentration of AuNPs, AgNPs and Ag–Au composite. However, Au–Ag nanocomposite showed the highest biofilm inhibition when compared with individual AuNPs and AgNPs. This synergistic anti-biofilm activity of Ag–Au nanocomposite has an importance in the development of novel therapeutics against multidrug-resistant bacterial biofilm.     

Evaluation of combined growth media for in vitro cultivation of oropharyngeal biofilms on prosthetic silicone

In the upper aerodigestive tract, biofilm deposits by oropharyngeal microbes can cause failure of medical polymer devices like voice prostheses. Previous studies on testing of inhibitive strategies still lack of comparability due to varying study protocols concerning growth media, microbial species and growth conditions. Goal of the study was therefore to test cultivation of a mixed biofilm of isolated oropharyngeal microbes under in vitro growth conditions using mixtures of common growth media. Mixtures of yeast peptone dextrose medium (YPD), fetal bovine serum (FBS), RPMI 1640, Yeast nitrogen base medium (YNB) and brain heart infusion (BHI) were tested to grow mixed biofilm deposits of Candida albicans, Candida tropicalis, Staphylococcus aureus, Streptococcus epidermidis, Rothia dentocariosa and Lactobacillus gasseri on medical grade silicone. Periodic assessment of living biofilm was performed over 22 days by a digital microscope and the cultivated biofilm structures were analyzed by scanning electron microscopy after completion of the study. Mixtures of BHI, YPD and FBS improved microscopic growth of multispecies biofilm deposits over time, while addition of RPMI and YNB resulted in reduction of visible biofilm deposit sizes. A mixtures of FBS 30%?+?YPD 70% and BHI 30%?+?YPD 70% showed enhanced support of permanent surface growth on silicone. Growth kinetics of in vitro multispecies biofilms can be manipulated by using mixtures of common growth media. Using mixtures of growth media can improve growth of longterm multispecies oropharyngeal biofilm models used for in vitro testing of antibiofilm materials or coatings for voice prostheses.

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