An in vitro bacterial adhesion assessment of surface-modified medical-grade PVC

Photoaging and release profile of acrylonitrile butadiene styrene microplastics under simulated solar radiation in water

Microplastics (MPs) pollution has become a major environmental problem and poses a risk to a variety of organisms. In this study, the photoaging behavior of acrylonitrile butadiene styrene microplastics (ABS-MP) in aqueous environment was investigated under simulated solar irradiation. Results showed that the long chains of ABS-MP broke under the light irradiation, and its thermal stability was reduced. ABS-MP was oxidized during photoaging and produced a large number of oxygen-containing functional groups. Structure destruction of ABS-MP decreased the formation of environmentally persistent free radicals (EPFRs) and further photoirradiation generated secondary EPFRs. Nuclear magnetic resonance (NMR) analysis of the aged leachates confirmed that ABS-MP was oxidized and some small molecular fragments were dropped during photoaging. Meanwhile, C-Br bond broke of additive tetrabromobisphenol A (TBBPA) resulting in more bromine released into water and Sb(III) of additive Sb₂O₃ was oxidized to Sb(V) during photoaging. These findings illustrate the necessity of considering the aging of MPs in natural environment, expand the understanding of the potential harm and fate of MPs in aqueous environment, which is important for the management of MPs.

Synthesis and characterization of functionalized modified PVC-chitosan as antimicrobial polymeric biomaterial

Amino acetic acid modified poly(vinyl chloride), MPVC, was obtained by chemical modification of PVC using glycine methyl ester. MPVC was used as a precursor to prepare some functionalized MPVC conjugates to be used in biomedical applications. MPVC-Cs was prepared by the chemical reaction of MPVC with chitosan as a natural polymer in absence and presence of epichlorohydrin (Ech) as a crosslinking agent. Further chemical modification was performed by the reaction of MPVC with Cs and salicylic acid in the absence in presence of Ech via one-pot reaction. The chemical structure of the formed MPVC, MPVC-Cs, MPVC-Cs/POH, MPVC-Cs/SA and MPVC-Cs/POH/SA was confirmed by the FTIR spectroscopic analysis, scanning electron microscopy, and thermogravimetric analysis (TGA). The antibacterial activity of the prepared MPVC and its conjugates was investigated against two Gram +ve bacteria (Staphylococcus aurous and Listeria monocytogenes) and (Escherichia coli and Salmonella typhi) as Gram −ve bacteria in addition to the Catondida albicans as yeast. Minimum inhibition concentration (MIC) was also determined for the prepared materials.

Plasma Mediated Chlorhexidine Immobilization onto Polylactic Acid Surface via Carbodiimide Chemistry: Antibacterial and Cytocompatibility Assessment

The development of antibacterial materials has great importance in avoiding bacterial contamination and the risk of infection for implantable biomaterials. An antibacterial thin film coating on the surface via chemical bonding is a promising technique to keep native bulk material properties unchanged. However, most of the polymeric materials are chemically inert and highly hydrophobic, which makes chemical agent coating challenging Herein, immobilization of chlorhexidine, a broad-spectrum bactericidal cationic compound, onto the polylactic acid surface was performed in a multistep physicochemical method. Direct current plasma was used for surface functionalization, followed by carbodiimide chemistry to link the coupling reagents of N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDAC) and N-Hydroxysuccinimide (NHs) to create a free bonding site to anchor the chlorhexidine. Surface characterizations were performed by water contact angle test, X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The antibacterial activity was tested using Staphylococcus aureus and Escherichia coli. Finally, in vitro cytocompatibility of the samples was studied using primary mouse embryonic fibroblast cells. It was found that all samples were cytocompatible and the best antibacterial performance observed was the Chlorhexidine immobilized sample after NHs activation.

Polymer Biointerfaces

Polymer biointerfaces are considered suitable materials for the improvement and development of numerous applications [...].

Advanced Drug-Eluting Poly (Vinyl Chloride) Surfaces Deposited by Spin Coating

Background and objectives: Medical devices such as catheters are used on a large scale to treat heart and cardiovascular diseases. Unfortunately, they present some important drawbacks (structure failure, calcifications, infections, thrombosis, etc.), with the main side effects occurring due to adhesion and proliferation of bacteria and living cells on the surface of the implanted devices. The aim of this work is to modify the surface of polyvinyl chloride (PVC), an affordable biocompatible material, in order to reduce these aforementioned side effects. Materials and Methods: The surface of PVC was modified by depositing a thin layer also of PVC that incorporates an active substance, dicoumarol (a well-known anticoagulant), by spin coating process. The modified surfaces were analyzed by Fourier-transform infrared (FT-IR) microscopy, Fourier-transform infrared (FT-IR) spectroscopy, Ultraviolet-visible spectroscopy (UV-VIS), and Scanning electron microscopy (SEM) in order to determine the surface morphology and behavior. The samples were tested for Gram-positive (S. aureus ATCC 25923) and Gram-negative (P. aeruginosa ATCC 27853) standard strains from American Type Culture Collection (ATCC). Results: The material obtained had a smooth surface with a uniform distribution of dicoumarol, which is released depending on the deposition parameters. The concentration of dicoumarol at the surface of the material and also the release rate is important for the applications for which the surface modification was designed. PVC modified using the proposed method showed a good ability to prevent salt deposition and decreased the protein adhesion, and the resistance to bacterial adherence was improved compared with standard PVC.

A rapid one-step surface functionalization of polyvinyl chloride by combining click sulfur(vi)-fluoride exchange with benzophenone photochemistry

We demonstrated a rapid one-step strategy for polyvinyl chloride surface functionalization by combining click “sulfur(vi)-fluoride exchange” (SuFEx) reaction with benzophenone photochemistry.

Prevention of bacterial adhesion to zwitterionic biocompatible mesoporous glasses

Novel materials, based on Mesoporous Bioactive Glasses (MBGs) in the ternary system SiO₂-CaO-P₂O₅, decorated with (3-aminopropyl)triethoxysilane (APTES) and subsequently with amino acid Lysine (Lys), by post-grafting method on the external surface of the glasses (named MBG-NH₂ and MBG-Lys), are reported. The surface functionalization with organic groups did not damage the mesoporous network and their structural and textural properties were also preserved despite the high solubility of MBG matrices. The incorporation of Lys confers a zwitterionic nature to these MBG materials due to the presence of adjacent amine and carboxylic groups in the external surface. At physiologic pH, this coexistence of basic amine and carboxilic acid groups from anchored Lys provided zero surface charge named zwitterionic effect. This behaviour could give rise to potential applications of antibacterial adhesion. Therefore, in order to assess the influence of zwitterionic nature in in vitro bacterial adhesion, studies were carried out with Staphylococcus aureus. It was demonstrated that the efficient interaction of these zwitterionic pairs onto the MBG surfaces reduced bacterial adhesion up to 99.9% compared to bare MBGs. In order to test the suitability of zwitterionic MBGs materials as bone grafts, their cytocompatibility was investigated in vitro with MC3T3-E1 preosteoblasts. These findings suggested that the proposed surface functionalization strategy provided MBG materials with notable antibacterial adhesion properties, hence making these materials promising candidates for local bone infection therapy.

STATEMENT OF SIGNIFICANCE

The present research work is focused in finding a preventive treatment of bone infection based on Mesoporous Bioactive Glasses (MBGs) with antibacterial adhesion properties obtained by zwitterionic surface modification. MBGs exhibit unique nanostructural, textural and bioactive characteristics. The novelty and originality of this manuscript is based on the design and optimization of a straightforward functionalization method capable of providing MBGs with zwitterionic surfaces that are able to inhibit bacterial adhesion without affecting their cytocompatibility. This new characteristic enhanced the MBG properties to avoid the bacterial adherence onto the implant surfaces for bone tissue engineering applications. Subsequently, it could help to decrease the infection rates after implantation surgery, which represents one of the most serious complications associated to surgical treatments of bone diseases and fractures.

IRRADIATION AND SILVER DEPOSITION FOR IMPROVEMENT OF NASOPHARYNGEAL AIRWAY MEDICAL DEVICE PROPERTIES

The thermal and mechanical properties of nasopharyngeal airway (NPA) samples are improved by irradiation using 4[Formula: see text]keV oxygen and nitrogen ion beams with different ion fluences varying from [Formula: see text] ions/cm2to [Formula: see text] ions/cm2. The thermal stability of NPA medical device increases with increasing nitrogen and oxygen ion fluences. The tensile strength increased from 48[Formula: see text]MPa for unirradiated sample to 74[Formula: see text]MPa for samples irradiated with nitrogen and to 58[Formula: see text]MPa for samples irradiated with oxygen ion, while the elongation at break decreases for irradiated samples. Silver thin films are deposited on NPA medical device samples using 4[Formula: see text]keV argon ion beam. The XRD spectra demonstrated that silver nanoparticles are deposited on NPA medical device substrate. The effects of Ag thin film on gram-positive and gram-negative bacteria are studied.

Plasma-modified nitric oxide-releasing polymer films exhibit time-delayed 8-log reduction in growth of bacteria

Tygon(®) and other poly(vinyl chloride)-derived polymers are frequently used for tubing in blood transfusions, hemodialysis, and other extracorporeal circuit applications. These materials, however, tend to promote bacterial proliferation which contributes to the high risk of infection associated with device use. Antibacterial agents, such as nitric oxide donors, can be incorporated into these materials to eliminate bacteria before they can proliferate. The release of the antimicrobial agent from the device, however, is challenging to control and sustain on timescales relevant to blood transport procedures. Surface modification techniques can be employed to address challenges with controlled drug release. Here, surface modification using H2O (v) plasma is explored as a potential method to improve the biocompatibility of biomedical polymers, namely, to tune the nitric oxide-releasing capabilities from Tygon films. Film properties are evaluated pre- and post-treatment by contact angle goniometry, x-ray photoelectron spectroscopy, and optical profilometry. H2O (v) plasma treatment significantly enhances the wettability of the nitric-oxide releasing films, doubles film oxygen content, and maintains surface roughness. Using the kill rate method, the authors determine both treated and untreated films cause an 8 log reduction in the population of both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Notably, however, H2O (v) plasma treatment delays the kill rate of treated films by 24 h, yet antibacterial efficacy is not diminished. Results of nitric oxide release, measured via chemiluminescent detection, are also reported and correlated to the observed kill rate behavior. Overall, the observed delay in biocidal agent release caused by our treatment indicates that plasma surface modification is an important route toward achieving controlled drug release from polymeric biomedical devices.

Immobilization of antibacterial chlorhexidine on stainless steel using crosslinking polydopamine film: Towards infection resistant medical devices

Chlorhexidine (CHX) is known for its high antibacterial substantivity and is suitable for use to bio-inert medical devices due to its long-term antibacterial efficacy. However, CHX molecules require a crosslinking film to be stably immobilized on bio-inert metal surfaces. Therefore, polydopamine (PDA) was utilized in this study to immobilize CHX on the surface of 316L type stainless steel (SS316L). The SS316L disks were pre-treated, modified with PDA film and immobilized with different concentrations of CHX (10mM-50mM). The disks were then subjected to various surface characterization analyses (ATR-FTIR, XPS, ToF-SIMS, SEM and contact angle measurement) and tested for their cytocompatibility with human skin fibroblast (HSF) cells and antibacterial activity against Escherichia coli and Staphylococcus aureus. The results demonstrated the formation of a thin PDA film on the SS316L surface, which acted as a crosslinking medium between the metal and CHX. CHX was immobilized via a reduction process that covalently linked the CHX molecules with the functional group of PDA. The immobilization of CHX increased the hydrophobicity of the disk surfaces. Despite this property, a low concentration of CHX optimized the viability of HSF cells without disrupting the morphology of adherent cells. The immobilized disks also demonstrated high antibacterial efficacy against both bacteria, even at a low concentration of CHX. This study demonstrates a strong beneficial effect of the crosslinked PDA film in immobilizing CHX on bio-inert metal, and these materials are applicable in medical devices. Specifically, the coating will restrain bacterial proliferation without suffocating nearby tissues.

Synthesis and Biomedical Applications of Poly((meth)acrylic acid) Brushes

Poly((meth)acrylic acid) (P(M)AA) brushes possess a number of distinctive properties that are particularly attractive for biomedical applications. This minireview summarizes recent advances in the synthesis and biomedical applications of P(M)AA brushes and brushes containing P(M)AA segments. First, we review different surface-initiated polymerization (SIP) methods, with a focus on recent progress in the surface-initiated controlled/living radical polymerization (SI-CLRP) techniques used to generate P(M)AA brushes with a tailored structure. Next, we discuss biomolecule immobilization methods for P(M)AA brushes, including physical adsorption, covalent binding, and affinity interactions. Finally, typical biomedical applications of P(M)AA brushes are reviewed, and their performance is discussed based on their unique properties. We conclude that P(M)AA brushes are promising biomaterials, and more potential biomedical applications are expected to emerge with the further development of synthetic techniques and increased understanding of their interactions with biological systems.

Rhamnolipid biosurfactant adsorption on a plasma-treated polypropylene surface to induce antimicrobial and antiadhesive properties

A glycolipid type of biosurfactant (rhamnolipid), which is obtained fromPseudomonas aeruginosaMA01, was adsorbed on a polypropylene film to produce an antimicrobial and antiadhesive polymeric surface for the first time.

Dual antibacterial effect of immobilized quaternary ammonium and aliphatic groups on PVC

Quaternary ammonium salts and lipophilic moieties were separately immobilized onto PVC to obtain a broad spectrum antimicrobial coating.

Antibacterial performance of alginic acid coating on polyethylene film

Alginic acid coated polyethylene films were examined in terms of surface properties and bacteriostatic performance against two most representative bacterial strains, that is, Escherichia coli and Staphylococcus aureus. Microwave plasma treatment followed by brush formation in vapor state from three distinguished precursors (allylalcohol, allylamine, hydroxyethyl methacrylate) was carried out to deposit alginic acid on the substrate. Surface analyses via various techniques established that alginic acid was immobilized onto the surface where grafting (brush) chemistry influenced the amount of alginic acid coated. Moreover, alginic acid was found to be capable of bacterial growth inhibition which itself was significantly affected by the brush type. The polyanionic character of alginic acid as a carbohydrate polymer was assumed to play the pivotal role in antibacterial activity. The cell wall composition of two bacterial strains along with the substrates physicochemical properties accounted for different levels of bacteriostatic performance.

HaCaT Keratinocytes Response on Antimicrobial Atelocollagen Substrates: Extent of Cytotoxicity, Cell Viability and Proliferation

The effective and widely tested biocides: Benzalkonium chloride, bronopol, chitosan, chlorhexidine and irgasan were added in different concentrations to atelocollagen matrices. In order to assess how these antibacterial agents influence keratinocytes cell growth, cell viability and proliferation were determined by using MTT assay. Acquired data indicated a low toxicity by employing any of these chemical substances. Furthermore, cell viability and proliferation were comparatively similar to the samples where there were no biocides. It means that regardless of the agent, collagen-cell-attachment properties are not drastically affected by the incorporation of those biocides into the substrate. Therefore, these findings suggest that these atelocollagen substrates enhanced by the addition of one or more of these agents may render effectiveness against bacterial stains and biofilm formation, being the samples referred to herein as “antimicrobial substrates” a promising view in the design of novel antimicrobial biomaterials potentially suitable for tissue engineering applications.

Protein adsorption on various plasma-treated polyethylene terephthalate substrates

Protein adhesion and cell response to plasma-treated polymer surfaces were studied. The polymer polyethylene terephthalate (PET) was treated in either an oxygen plasma to make the surface hydrophilic, or a tetrafluoromethane CF₄ plasma to make the surface hydrophobic. The plasma source was radiofrequency (RF) discharge. The adsorption of albumin and other proteins from a cell-culture medium onto these surfaces was studied using a quartz crystal microbalance (QCM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The cellular response to plasma-treated surfaces was studied as well using an MTT assay and scanning electron microscopy (SEM). The fastest adsorption rate was found on the hydrophilic oxygen plasma-treated sample, and the lowest was found on the pristine untreated sample. Additionally, the amount of adsorbed proteins was higher for the oxygen-plasma-treated surface, and the adsorbed layer was more viscoelastic. In addition, cell adhesion studies support this finding because the best cell adhesion was observed on oxygen-plasma-treated substrates.

Recent Progress in Surface Modification of Polyvinyl Chloride

Surface modification of polymers has become a vibrant field of research on account of a myriad of rationales which stimulated numerous efforts. The current paper serves as a condensed survey of the advances made through different approaches adopted for tuning the surface properties of polyvinyl chloride as a homopolymer extensively used on a large scale. Though it does not address all challenges involved, this paper communicates and highlights, through concise discussion, the findings of the efforts undertaken in recent decades. It is ultimately concluded with a perspective of the huge capacities and promising future directions.

Review of immobilized antimicrobial agents and methods for testing

Antimicrobial surfaces for food and medical applications have historically involved antimicrobial coatings that elute biocides for effective kill in solution or at surfaces. However, recent efforts have focused on immobilized antimicrobial agents in order to avoid toxicity and the compatibility and reservoir limitations common to elutable agents. This review critically examines the assorted antimicrobial agents reported to have been immobilized, with an emphasis on the interpretation of antimicrobial testing as it pertains to discriminating between eluting and immobilized agents. Immobilization techniques and modes of antimicrobial action are also discussed.

Superhydrophobic, nanotextured polyvinyl chloride films for delaying Pseudomonas aeruginosa attachment to intubation tubes and medical plastics

Bacterial attachment onto the surface of polymers in medical devices such as polyvinyl chloride (PVC) is influenced by the physicochemical properties of the polymer, including its surface hydrophobicity and roughness. In this study, to prevent biofilm formation onto PVC devices, the PVC surface was modified using a combination of solvent (tetrahydrofuran) and non-solvents (i.e. ethanol and methanol). The surface of unmodified PVC was smooth and relatively hydrophobic (water contact angle (CA)=80°). Ethanol-treated PVCs revealed the presence of micron-sized particulates and porous structures as the concentration of ethanol was increased. Surface hydrophobicity (measured in terms of CA) increased from 73° to 150° as the ethanol concentration increased from 15% to 35% (v/v). In general, methanol-treated PVCs were more hydrophilic compared to those treated with ethanol. The colonization of Pseudomonas aeruginosa PAO1 onto unmodified PVC surface was rapid, and individual bacterial cells could be seen after 6h incubation. On the surface of treated PVC, the secretion of extracellular matrix layers was evident at 18 h and P. aeruginosa PAO1 start to form microcolonies at 24h of incubation. The initial attachment of P. aeruginosa PAO1 was delayed to 18 and 24h, respectively in the PVCs treated with 25% (v/v) and 35% (v/v) ethanol. It can be concluded that the treatment used in this study to prepare superhydrophobic PVC surface prevented the colonization of bacteria up to 24h after culture.

Preparation of active antibacterial LDPE surface through multistep physicochemical approach: I. Allylamine grafting, attachment of antibacterial agent and antibacterial activity assessment

Low-density polyethylene (LDPE) samples were treated in air plasma discharge, coated by polyallyamine brush thought copolymeric grafting surface-from reaction and deposited four common antibacterial agents (benzalkonium chloride, bronopol, chlorhexidine and triclosan) to gain material with active antibacterial properties. Surface characteristics were evaluated by static contact angle measurement with surface energy evaluation ATR-FTIR, X-ray Photoelectron Spectroscopy (XPS) and SEM analysis. Inhibition zone on agar was used as in vitro test of antibacterial properties on two representative gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli) strains. It was confirmed, that after grafting of polyallyamine, more antibacterial agent is immobilized on the surface. The highest increase of antibacterial activity was observed by the sample containing triclosan. Samples covered by bronopol did not show significant antibacterial activity.

Inhibition of bacterial adhesion on biocompatible zwitterionic SBA-15 mesoporous materials

In this manuscript in vitro bacterial adhesion assays using Escherichia coli on different SBA-15 nanostructured ceramics have been performed. For this purpose pure silica, NH(2) or COOH monofunctionalized, and NH(2)/COOH bifunctionalized SBA-15 mesoporous materials have been used. Material characterization reveals that both NH(2)/COOH and NH(2) functionalized SBA-15 materials exhibit a zwitterionic character due to the presence of -NH(3)(+)/COO(-) or -NH(3)(+)/SiO(-) moieties, respectively. In vitro adhesion assays have been carried out at the pH at which the zwitterionic nature of both of these samples is preserved, i.e. pH 5.5. The results show that the presence of both positive and negative moieties with an overall neutral charge leads to reduced E. coli adhesiveness. In vitro tests with cultured human Saos-2 osteoblasts have been carried out to evaluate the biocompatibility of the different materials at the physiological pH of 7.4. The results demonstrate that all materials exhibit good biocompatibility, with Saos-2 osteoblasts adhering, proliferating and maintaining their morphological and functional characteristics. This novel family of zwitterionic mesoporous materials opens up promising expectations in diverse biomedical applications, such as preventing some side-effects associated with bone implant infections.

Plasma-assisted surface modification of organic biopolymers to prevent bacterial attachment

Despite many synthetic biomaterials having physical properties that are comparable or even superior to those of natural body tissues, they frequently fail due to the adverse physiological reactions they cause within the human body, such as infection and inflammation. The surface modification of biomaterials is an economical and effective method by which biocompatibility and biofunctionality can be achieved while preserving the favorable bulk characteristics of the biomaterial, such as strength and inertness. Amongst the numerous surface modification techniques available, plasma surface modification affords device manufacturers a flexible and environmentally friendly process that enables tailoring of the surface morphology, structure, composition, and properties of the material to a specific need. There are a vast range of possible applications of plasma modification in biomaterial applications, however, the focus of this review paper is on processes that can be used to develop surface morphologies and chemical structures for the prevention of adhesion and proliferation of pathogenic bacteria on the surfaces of in-dwelling medical devices. As such, the fundamental principles of bacterial cell attachment and biofilm formation are also discussed. Functional organic plasma polymerised coatings are also discussed for their potential as biosensitive interfaces, connecting inorganic/metallic electronic devices with their physiological environments.

Stimuli-responsive networks grafted onto polypropylene for the sustained delivery of NSAIDs

Co-polymers of N-isopropyl acrylamide (NIPAAm) and N-(3-aminopropyl) methacrylamide hydrochloride (APMA) were grafted on polypropylene (PP) films by means of a γ-ray pre-irradiation method, with the aim of developing medical devices able to load non-steroidal anti-inflammatory drugs (NSAIDs) and to control their release under physiological conditions. The NIPAAm/APMA molar ratios in the grafts, estimated by Fourier transform infrared attenuated total reflection spectroscopy and X-ray photoelectron spectroscopy analysis, were 4.76 and 1.23 for PP-g-(1M NIPAAm-r-0.5M APMA) and PP-g-(1M NIPAAm-r-1M APMA), respectively. By varying the reaction time, different degrees of grafting were achieved, while the monomer ratio was kept constant. PP-g-(NIPAAm-r-APMA) films showed temperature-responsive swelling, smaller friction coefficients, hemolysis and thrombogenicity and higher cell compatibility, did not elicit secretion of cytokines, and took up remarkable amounts of diclofenac and ibuprofen and sustained delivery for several hours in phosphate buffer, pH 7.4. Coating with carboxymethyl dextran of diclofenac-loaded PP-g-(NIPAAm-r-APMA) films caused a minor discharge of the drug but did not alter the drug release rate.