New Anti-infective Coatings of Surgical Sutures Based on a Combination of Antiseptics and Fatty Acids

Wound infection is a complication feared in surgery. The aim of this study was to develop new anti-infective coatings of surgical sutures and to compare the anti-microbial effectiveness and biocompatibility to the well-established Vicryl Plus^®. Synthetic absorbable PGA surgical sutures were coated with three different chlorhexidine concentrations and two different octenidine concentrations in combination with palmitic acid and lauric acid. Drug-release kinetics lasting 96 h were studied in phosphate-buffered saline at 37°C. Anti-infective characteristics were determined by measuring the change in optical density of Staphylococcus aureus suspensions charged with coated sutures over time. Microorganisms adsorbed at the surface of coated sutures were assessed on blood agar plates and coated sutures eluted for 24 h were placed on bacterial lawns cultured on Mueller–Hinton plates to prove retained anti-microbial potency. A cell proliferation assay was performed to assess the degree of cytotoxicity. Anti-infective characteristics and biocompatibility were compared to Vicryl Plus^®. A coating technology for slow-release drug-delivery systems on surgical sutures could be developed. All coatings showed a continuous drug release within 96 h. Individual chlorhexidine and octenidine coated sutures showed superior anti-infective characteristics but inferior biocompatibility in comparison to Vicryl Plus^®. We conclude that the developed anti-infective suture coatings consisting of lipid-based drug-delivery systems in combination with antiseptics are highly effective against bacterial colonization in vitro; however, drug doses have to be adjusted to improve biocompatibility.     

Cell adhesion and proliferation are reduced on stainless steel coated with polysaccharide-based polymeric formulations

Hydromer's polymeric formulations F200 and F202 were evaluated after application to a synthetic substrate for effects on cell adhesion and proliferation. A significant reduction in cell adhesion was observed when cells grown on medical-grade stainless steel coated with these polymers were stained and examined under a fluorescence microscope. This reduction in cell adhesion/proliferation was confirmed when cells were isolated and analyzed by the MTS cell proliferation assay. The rate of growth of cells on F200- and F202-coated stainless steel monitored over a period of 7 days was significantly less than that observed on uncoated stainless steel, suggesting that the rate of growth of cells was reduced. The adhesion/proliferation of human umbilical vein endothelial cells (HUVEC) to coated substrates was also decreased significantly, indicating that the reduction in cell adhesion/proliferation is not restricted to only fibroblasts. Additional studies have indicated that the adhesion/proliferation of murine fibroblasts and human endothelial cells to stainless coated with a modified formulation exhibiting a high degree of lubricity was also significantly reduced. This lubricious formulation was also observed to be effective in reducing platelet adhesion, data supporting the view that lubricity also contributes to a reduction in cell and platelet adhesion. The application of these polymeric coatings on devices designed for medical implantation may not only prevent thrombus formation but may also retard the process of restenosis.     

PDMS-based polyurethanes with MPEG grafts: Mechanical properties,bacterial repellency,and release behavior of rifampicin

PDMS-based polyurethanes (PUs) grafted with monomethoxy poly(ethylene glycol) (MPEG) were synthesized to develop a coating material for urinary catheters with a silicone surface for minimizing urinary tract infections. MPEG was grafted on PDMS-based PUs by two methods depending on the PU synthetic routes: esterification and allophanate reactions. It was confirmed from mechanical characterization that an increase of the hard segment amount enhanced the ultimate strength and Young's modulus, while reducing elongation at the end-points. The incorporation of MPEG in PDMS-based PUs induced a decrease in tensile strength and Young's modulus, and increased elongation at the break point due to its high flexibility. When hydrated in distilled water, mechanical properties of all PUs synthesized in this study deteriorated due to water absorption. It was evident from the bacterial adhesion test that PDMS-based PUs showed moderate resistance to adhesion of E. coli on their surfaces compared to Pellethane®, while the incorporation of MPEG significantly enhanced repellency to bacteria, including E. coli and S. epidermidis. We also studied the release behavior of an antibiotic drug, rifampicin, from the polymeric devices fabricated by solvent evaporation. Although rifampicin is hydrophilic and soluble in pH 7.4 phosphate buffer, it showed a sustained release over 45 days from PDMS-based PUs with MPEG that were grafted on ethylene glycol residues by allophanate reaction. This release characteristic was predominantly influenced by a hydrogen bond interaction between the polymers and rifampicin, which was confirmed through an ATR-IR study. This may imply that the specific interaction is responsible for the delayed release. Considering the mechanical properties, morphologies of drug-incorporated polymeric matrices, and drug release behaviors, PDMS-based PU with MPEG that were grafted on ethylene glycol (a chain extender) residues by allophanate reaction showed better material properties for uretharal catheter coating pusposes in order to minimize urinary tract infections.     

Differential growth on sutures of tendon cells derived from torn human rotator cuff

Rotator cuff tendon pathology is proposed to account for 30-70% of all shoulder pain and surgical repair with a nonabsorbable suture is the common option for painful rotator cuff tears that have failed conservative treatment. A number of studies have suggested the beneficial effect of augmenting the repair with implants constructed from polymers used for sutures. Thus, it was of interest to investigate the affinity of tendon-derived fibroblasts, often thought to be the repairing agents of torn tendons, to commonly used sutures. The aim of this comparative study was to evaluate the suitability of these sutures for the construction of a patch by measuring cell survival, proliferation, and migration of human tendon-derived fibroblasts on different sutures. To ensure relevance to the target tissue, cells used in this study were obtained from torn human supraspinatus tendons. An initial comparison of cell proliferation on suture mats showed an overall positive proliferation on polyester (Ethibond) and polydioxanone (PDSII) mats and a reduction of proliferation on vicryl (polyglactin 910) compared to day one. The results also showed that the degradation products of vicryl had a negative effect on cell growth over 10 weeks. Of the commercial sutures selected and tested, Ethibond showed the best performance in terms of cell attachment and increase in biomass. The degradable PDSII also showed good interaction with cells in vitro, but relatively poor cell adhesion. This study provides useful and clinically relevant information, which could help to guide future considerations for candidate materials from which to construct tissue repair patches.     

Adhesion of human peripheral lymphocytes on biomaterials preadsorbed with fibronectin and vitronectin

The adhesion of human peripheral lymphocytes (HPL) was studied after preadsorption of fibronectin (FN) and vitronectin (VN) on hydrophilic glass and hydrophobic octadecyl glass. The adhesion of HPL was shown to be dependent not only on the wettability but also on the protein preadsorbed. Vitronectin expressed not only a higher extent of adhesion under static conditions but also a stronger interaction with HPL, indicated by the low detachment under shear stress. The flow experiments also demonstrated that FN adsorbed on octadecyl glass may undergo conformational changes because HPL could be easily removed. Scanning electron microscopy revealed that HPL on both FN-and VN-coated glass spread well whereas particularly on FN-coated octadecyl glass less cell spreading was observed; moreover, some round cells were detected. The typing of adherent HPL by immunofluorescence microscopy showed that on FN- and VN-coated glass about 70% of all HPL were T-cells (CD 3+). However, on octadecyl glass, particularly on VN, a smaller percentage of CD 3+cell was observed. The testing for the β₁ integrin-the receptor for FN and the α_v integrin-the receptor for VN demonstrated that about 70% of all cells on FN-coated glass were positive for the β₁ integrin. On VN-coated glass, however, only 5% of HPL were positive for the β₁ integrin. Although on VN a high adhesion and strong binding of HPL was observed, no presence of the α_vintegrin was detected.     

Preparation,characterization, and in vitro drug release behavior of glutathione-sensitive long-circulation micelles based on polyethylene glycol prodrug

In this paper, a kind of glutathione-sensitive polymeric micelles was prepared through assembling in aqueous solution of an amphiphilic polymeric prodrug which was synthesized by linkage of 6-mercaptopurine (6-MP) and polyethylene glycol monomethyl ether using propiolic acid as a connecting arm. The glutathione (GSH)-sensitive strategy is based on a Michael addition–elimination reaction, that is the amphiphilic polymeric prodrug which contains α, β-unsaturated carbonyl group acts as a Michael acceptor to receive the attack of nucleophile – glutathione, and undergoes elimination reaction to release the original drug. Transmission electron microscope observation showed that the polymeric micelles (PMs) had a spherical-like morphology with a mean diameter of 28 ± 3.2 nm. The dynamic light scattering investigation data exhibited that the size and distribution changes of PMs are negligible after being placed for 15 days. In vitro drug release study indicated that only less than 13% of 6-MP was released from the micelles under GSH stimulation at micromolar level, while 34.5, 53.7, and 77.8% accumulative release rates were achieved under GSH stimulation at millimolar level (1, 2 and 10 mM), respectively. The cell inhibition rate of PM solution against HL-60 cells carried out by MTT method reached 85%. The cellular uptake and the intracellular drug release of PMs in HL-60 cells were observed through determining the intracellular 6-MP content by UV–vis spectrophotometer. In vitro macrophage uptake study showed a low phagocytosis rate, indicating the long-circulation ability of the PMs.     

Bacterial adhesion on biomedical surfaces covered by micrometric silver Islands

A set of Cu-Mn-O and Ag-Cu-Mn-O films were sputter-deposited onto polished Ti-6Al-4V coupons and the microbiological adherence of Staphylococcus sp. was studied in these biomedical surfaces modified by using advanced ternary and quaternary oxides, these latter incorporated micrometric silver islands. Silver is known to have a natural biocidal character and its presence in the surface of Ti-6Al-4V forming large micrometric islands. In principle, predicted to enhance the antimicrobial properties of biomedical surfaces. Microbial adhesion tests were performed using collection strains and six clinical Staphylococcus aureus and Staphylococcus epidermidis strains. The adherence study was performed using a previously published protocol by Kinnari et al. Collection strains and clinical strains showed decreased adherence to modified materials; however, only on the clinical strains were there statistically significant differences between Cu-Mn-O and Ag-Cu-Mn-O containing silver islands. Nanocrystalline silver dissolves and releases both Ag(+) and Ag(0) whereas other silver sources release only Ag+. We can conclude that nanocrystalline silver coating, confirmed by XRD, appears to alter the biological properties of the solution, particularly antimicrobial activity.     

Platelet and cell interactions on gold sputter-deposited polymeric surfaces

Surface treatment as gold sputter-deposited treatment onto various polymeric surfaces has been investigated to improve the cell-, tissue- and blood-compatibility. Surface treated samples were characterized by measurement of contact angle goniometer and electron spectroscopy for chemical analysis (ESCA). The contact angles on the gold-coated polymeric surfaces decreased from 95-65 degrees to around 50 degrees, i.e., increased hydrophilicity due to incorporation of gold thin layer. From the results of ESCA analysis of the modified polymeric surfaces, surface modification by the gold-sputter method was successfully performed. Morphology of the adhered platelets on the gold-coated polymeric surfaces showed lesser activating than control, and the number of adhered platelets surface modified samples decreased with decreasing water contact angle. Fibroblast cell adhesion and growth on the gold-coated polymeric surfaces were more active than those of control. It seems that surface wettability and surface chemistry of gold play important roles for platelet adhesion and cell adhesion, spreading and growth.     

Washing the dog reduces dog allergen levels, but the dog needs to be washed twice a week

BACKGROUND: Many asthmatic patients allergic to dogs refuse to part with their dog, and it is essential to develop techniques for lowering exposure with a dog in the home. OBJECTIVE: This study investigated the effect of dog washing on the subsequent recovery of Can f 1 from dog hair clippings and on the airborne allergen over a 7-day period. METHODS: Dogs, which had not been washed for at least the previous 3 weeks, were washed with a hand-held shower and proprietary shampoo. Hair clippings and dander samples from 25 dogs were collected before and immediately after washing. After these initial studies, 16 dogs had a small tuft of hair clipped from the collar or spinal area before washing and then daily for the next 7 days. Air sampling was performed in 5 homes, and the air samples were collected (airflow rate, 9 L/min) over an 8-hour period per day on 10 consecutive days (3 days of baseline sampling before washing and then 7 consecutive days after washing). Can f 1 level was measured by using 2-site ELISA. RESULTS: Washing significantly reduced recoverable Can f 1 from clippings (84% reduction: from 73 microg/g to 12 microg/g [geometric mean]; P <.0001) and from dander samples (86% reduction: from 347 microg/g to 50 microg/g [geometric mean]; P <.0001). There was a significant reduction in Can f 1 levels in dog hair over the observed 8-day period (F = 18.4, P <. 0001). By using a multiple comparison test, this observed significance was found to be due to the difference between the baseline levels and those on days 1 and 2 after washing, with no difference in the baseline Can f 1 compared with days 3 to 7. Airborne Can f 1 levels showed a downward trend, which reached statistical significance when the data were grouped into 3 sampling periods as follows: baseline (ie, mean of 3 days before sampling) was compared with days 1 to 4 after washing (41% reduction, 95% CI 13%-60%) and days 5 to 7 after washing (61% reduction, 95% CI 2%-84%; P =.014). CONCLUSIONS: Washing the dog reduces recoverable allergen from dog hair and dander. The dog needs to be washed at least twice a week to maintain the reduction in recoverable Can f 1 from its hair. Washing the dog achieves a modest reduction in the level of airborne Can f 1 in homes with a dog.     

Biocompatibility and antibacterial activity of plasma sprayed titania coating grafting collagen and gentamicin

In this article, the plasma sprayed titania coatings were treated by grafting pure and gentamicin loaded collagen to improve the biocompatibility and antibacterial activity. The biocompatibility of the titania coating grafting collagen was evaluated by in vitro cell culturing test. The release rate of gentamicin from collagen was measured in tris-HCl buffer using UV spectrophotometer, and the antibacterial activity of the titania coating with gentamicin against Staphylococcus aureus was examined using the zone of inhibition test. The results showed that collagen was successfully grafted on the surface of titania coatings treated by sulfuric acid. The in vitro cell culturing test revealed that collagen significantly improved the cell adhesion and proliferation on the surface of titania coatings. The gentamicin loaded in collagen matrix could retain a sustained release in tris-HCl for 30 days, which was efficient to protect against the postoperative infection caused by S. aureus. The results indicated that the plasma sprayed titania coating grafting collagen and gentamicin would have the antibacterial activity together with the biocompatibility, which might be beneficial for the long term stability and surgical success rate of implants.     

Surgical suture assembled with polymeric drug-delivery sheet for sustained,local pain relief

Surgical suture is a strand of biocompatible material designed for wound closure, and therefore can be a medical device potentially suitable for local drug delivery to treat pain at the surgical site. However, the preparation methods previously introduced for drug-delivery sutures adversely influenced the mechanical strength of the suture itself – strength that is essential for successful wound closure. Thus, it is not easy to control drug delivery with sutures, and the drug-delivery surgical sutures available for clinical use are now limited to anti-infection roles. Here, we demonstrate a surgical suture enabled to provide controlled delivery of a pain-relief drug and, more importantly, we demonstrate how it can be fabricated to maintain the mechanical strength of the suture itself. For this purpose, we separately prepare a drug-delivery sheet composed of a biocompatible polymer and a pain-relief drug, which is then physically assembled with a type of surgical suture that is already in clinical use. In this way, the drug release profiles can be tailored for the period of therapeutic need by modifying only the drug-loaded polymer sheet without adversely influencing the mechanical strength of the suture. The drug-delivery sutures in this work can effectively relieve the pain at the surgical site in a sustained manner during the period of wound healing, while showing biocompatibility and mechanical properties comparable to those of the original surgical suture in clinical use.     

The glass ionomer cement: the sources of soluble fluoride

This study aimed to investigate certain processes of fluoride production which enable glass ionomer cements to leach fluoride. Two fluoroaluminosilicate glasses, G338 and LG26 were used. The free and total fluoride which could be dissolved from the glasses was measured, before and after acetic acid washing. Both glasses contained appreciable amounts of soluble fluoride prior to any acid treatment. The latter process reduced the amount to some 75% of the original levels. Replacing the customary polymeric acid with propionic acid produced a cement which disintegrated in water allowing the amount of fluoride generated by the cement forming process to be measured. Cement production increased soluble fluoride by a further 3%. Both glasses behaved similarly when undergoing the various processes. G338 produced significantly greater quantities of fluoride, of the order of 10, compared with LG26 although containing only three times the amount of fluoride in the glass formula. A substantial proportion, over half, of the total fluoride was complexed especially after contact with cement and when G338 was used. During the period of the experiment, 21 days, total fluoride release did not seem to depend on the square root of time.     

PDMS-based polyurethanes with MPEG grafts: mechanical properties, bacterial repellency, and release behavior of rifampicin

PDMS-based polyurethanes (PUs) grafted with monomethoxy poly(ethylene glycol) (MPEG) were synthesized to develop a coating material for urinary catheters with a silicone surface for minimizing urinary tract infections. MPEG was grafted on PDMS-based PUs by two methods depending on the PU synthetic routes: esterification and allophanate reactions. It was confirmed from mechanical characterization that an increase of the hard segment amount enhanced the ultimate strength and Young's modulus, while reducing elongation at the end-points. The incorporation of MPEG in PDMS-based PUs induced a decrease in tensile strength and Young's modulus, and increased elongation at the break point due to its high flexibility. When hydrated in distilled water, mechanical properties of all PUs synthesized in this study deteriorated due to water absorption. It was evident from the bacterial adhesion test that PDMS-based PUs showed moderate resistance to adhesion of E. coli on their surfaces compared to Pellethane, while the incorporation of MPEG significantly enhanced repellency to bacteria, including E. coli and S. epidermidis. We also studied the release behavior of an antibiotic drug, rifampicin, from the polymeric devices fabricated by solvent evaporation. Although rifampicin is hydrophilic and soluble in pH 7.4 phosphate buffer, it showed a sustained release over 45 days from PDMS-based PUs with MPEG that were grafted on ethylene glycol residues by allophanate reaction. This release characteristic was predominantly influenced by a hydrogen bond interaction between the polymers and rifampicin, which was confirmed through an ATR-IR study. This may imply that the specific interaction is responsible for the delayed release. Considering the mechanical properties, morphologies of drug-incorporated polymeric matrices, and drug release behaviors, PDMS-based PU with MPEG that were grafted on ethylene glycol (a chain extender) residues by allophanate reaction showed better material properties for uretharal catheter coating pusposes in order to minimize urinary tract infections.     

Osteoblast-like cell attachment to and calcification of novel phosphonate-containing polymeric substrates

In an attempt to interact natural bone and bone cells with biomaterials and to begin to develop modular tissue engineering scaffolds, substrates containing phosphonate groups were identified to mimic mineral-protein and natural polymer-protein interactions. In this study, we investigated poly(vinyl phosphonic acid) copolymer integration with existing materials as a graft-copolymer surface modification. Phosphonate-containing copolymer-modified surfaces were created and shown to have varying phosphate content within different polymeric surfaces. As the phosphonate content in the monomer feed approached 30% vinyl phosphonic acid, increased osteoblast-like cell adhesion (3- to 8-fold increase in adhesion) and proliferation (2- to 10-fold increase in proliferation rate) was observed. Since surfaces modified with 30% vinyl phosphonic acid in the feed exhibited a maximal cell adhesion and proliferation (9.4 x 10(4) cells/cm(2)/day), it was hypothesized that this copolymer composition was optimal for protein-polymer interactions. Osteoblast-like cells formed confluent layers and were able to differentiate on all surfaces that contained vinyl phosphonic acid. Most importantly, cells interacting with these surfaces were able to significantly mineralize the surface. These results suggest that phosphonate-containing polymers can be used to integrate biomaterials with natural bone and could be used for tissue engineering applications.     

Biological responses of silver-coated thermosets: An in vitro and in vivo study

Bisphenol A glycidylmethacrylate (BisGMA)/triethyleneglycol dimethacrylate (TEGDMA) thermosets are biomaterials commonly employed for orthopedic and dental applications; for both these fields, bacterial adhesion to the surface of the implant represents a major issue for the outcome of the surgical procedures. In this study, the antimicrobial properties of a nanocomposite coating formed by polysaccharide 1-deoxylactit-1-yl chitosan (Chitlac) and silver nanoparticles (nAg) on methacrylate thermosets were studied. The Chitlac–nAg system showed good anti-bacterial and anti-biofilm activity although its biocidal properties can be moderately, albeit significantly, inhibited by serum proteins. In vitro studies on the silver release kinetic in physiological conditions showed a steady metal release associated with a gradual loss of antimicrobial activity. However, after 3 weeks there was still effective protection against bacterial colonization which could be accounted for by the residual silver. This time-span could be considered adequate to confer short-term protection from early peri-implant infections. Preliminary in vivo tests in a mini-pig animal model showed good biological compatibility of Chitlac–nAg-coated materials when implanted in bony tissue. The comparison was made with implants of titanium Ti6Al4V alloy and with a Chitlac-coated thermoset. Bone healing patterns and biocompatibility parameters observed for nAg-treated material were comparable with those observed for control implants.     

Prevention of Staphylococcus epidermidis biofilm formation using a low-temperature processed silver-doped phenyltriethoxysilane sol-gel coating

Sol-gel coatings which elute bioactive silver ions are presented as a potential solution to the problem of biofilm formation on indwelling surfaces. There is evidence that high-temperature processing of such materials can lead to diffusion of silver away from the coating surface, reducing the amount of available silver. In this study, we report the biofilm inhibition of a Staphylococcus epidermidis biofilm using a low-temperature processed silver-doped phenyltriethoxysilane sol-gel coating. The incorporation of a silver salt into a sol-gel matrix resulted in an initial high release of silver in de-ionised water and physiological buffered saline (PBS), followed by a lower sustained release for at least 6 days-as determined by graphite furnace-atomic absorption spectroscopy (GF-AAS). The release of silver ions from the sol-gel coating reduced the adhesion and prevented formation of a S. epidermidis biofilm over a 10-day period. The presence of surface silver before and after 24 h immersion in PBS was confirmed by X-ray photoelectron spectroscopy (XPS). These silver-doped coatings also exhibited significant antibacterial activity against planktonic S. epidermidis. A simple test to visualise the antibacterial effect of silver release coatings on neighbouring bacterial cultures is also reported.     

Physiological concentrations of albumin stimulate chorionic gonadotrophin and placental lactogen release from human term placental explants

This study investigates whether albumin, a major plasma protein in direct contact with the trophoblast in vivo, can modulate human chorionic gonadotrophin (HCG) and human placental lactogen (HPL) releases from placental explants. Incubating explants with a near physiological, i.e. 5%, concentration of human or bovine albumin during 30 min increased HCG and HPL release by at least 150%. This albumin effect was not mediated by any difference in hormone adsorption onto glass surfaces. In contrast to the sustained stimulation of hormone releases elicited by the addition of 10 mmol/l extracellular calcium, the albumin-mediated secretory responses were transient. However, the albumin- and calcium-stimulatory effects were abolished at 4 degrees C, depressed by 0.36 mmol/l cycloheximide or 1 mmol/l colchicine and potentiated by 40 micromol/l cytochalasin B. Moreover, the stimulatory effect of albumin on the hormone releases was not modified in the absence of Ca(2+) or in the presence of 1 or 10 mmol/l Ca(2+) in the extracellular milieu. These data suggest that albumin is involved, at physiological concentration, in the secretion of HCG and HPL by human placenta. The cellular mechanism(s) underlying the albumin-mediated secretory responses may be partly different from those involved during the calcium-mediated stimulation.     

Sol Particle Immunoassay (SPIA)

We describe the use of inorganic (metal) colloidal particles as a label for immunoassays. Dose-response curves for human placental lactogen (HPL) and human chorionic gonadotrophin (HCG) were obtained with sandwich immunoassays, using conjugates consisting of antibody-coated colloidal gold or silver particles. Several techniques were used to measure the amount of bound conjugate, viz. colorimetry and carbon rod atomic absorption spectrophotometry (CRAAS). At higher antigen concentrations the results of the assay could be read by the naked eye.

Using gold particles as label and CRAAS as detection method, we found a detection limit for a sandwich HPL sol particle immunoassay (SPIA) of 1,4 pmol/l, which was equal to that of an optimalized competitive radioimmunoassay. When using a colorimeter the detection limit for HPL of this SPIA was 5,4 pmol/l, which was superior to that of a corresponding sandwich enzyme-immunoassay (EIA). HPL and HCG were also simultaneously determined, using micro-titration plates, coated with a mixture of anti-HPL and anti-HCG, and a mixture of silver particle anti-HPL conjugate and gold particle anti-HCG conjugate. CRAAS was used to measure the bound amount of silver and gold conjugate. This simultaneous assay requires more work in order to obtain better sensitivities.     

5-Fluorouracil–lipid conjugate: Potential candidate for drug delivery through encapsulation in hydrophobic polyester-based nanoparticles

The encapsulation of 5-fluorouracil (5-FU) in hydrophobic polymeric materials is made feasible by a lipid-based prodrug approach. A lipid–5-FU conjugate of 5-FU with palmitic acid was synthesized in two-step process. A synthesized dipalmitoyl derivative (5-FUDIPAL) was characterized using Fourier transform infrared spectroscopy and ¹H-nuclear magnetic resonance. The 5-FUDIPAL was encapsulated in polyester-based polymers by the double emulsion–solvent evaporation method. The nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy and dynamic light scattering. The thermal stability was assessed by differential scanning calorimetry data. In vitro release kinetics measurements of the drug from nanoparticles showed the controlled release pattern over a period of time. Cytotoxicity measurements by MTT assay confirmed that dipalmitoyl derivative in nano formulation successfully inhibited the cell growth. Thus the combined physical and biological evaluation of the different polyester-based nanoparticle containing the modified drug showed a facile approach to delivering 5-FU to the tumour site with enhanced efficacy.     

Prevention of pin track infection in external fixation with silver coated pins: clinical and microbiological results

Pin tract infection is a frequent complication of external fixation; according to literature its frequency ranges from 2-30%. The recent introduction of silver coating of polymeric materials was found to decrease bacterial adhesion; its clinical use with Foley catheters and central venous catheters led to significant results. To verify the ability of the same silver coating to decrease the bacterial colonization on external fixation screws, a prospective randomized study was carried out on 24 male patients; a total of 106 screws were implanted in the lower limb to fix femoral or tibial diaphyseal fractures: 50 were coated with silver and 56 were commercially available stainless steel screws. Although the coated screws resulted in a lower rate of positive cultures (30.0%) than the uncoated screws (42.9%), this difference was not statistically significant (p = 0.243). The clinical behavior of the coated screws did not differ from that of the uncoated ones. Furthermore, the implant of silver-coated screws resulted in a significant increase in the silver serum level. These results led us to consider it ethically unacceptable to continue this investigation.