罐内水性涂料抗微生物侵染的试验方法研究

本文介绍了推荐性国家标准GB/T30792-2014《罐内水性涂料抗微生物侵染试验方法》制订的必要性及制订依据。针对标准适用范围、测试菌种、测试条件和实验程序等内容分别进行了系统的描述。     

Fast corroding,thin magnesium coating displays antibacterial effects and low cytotoxicity

Bacterial colonisation and biofilm formation are characteristics of implant-associated infections. In search of candidates for improved prosthetic materials, fast corroding Mg-based coatings on titanium surfaces were examined for their cytotoxic and antimicrobial properties. Human osteoblasts and Staphylococcus epidermidis were each cultured on cylindrical Ti samples coated with a thin layer of Mg/Mg₄₅Zn₅Ca, applied via magnetron sputtering. Uncoated titanium samples served as controls. S. epidermidis was quantified by counting colony forming units. The biofilm-bound fraction was isolated via ultrasonic treatment, and the planktonic fraction via centrifugation. Biofilm-bound S. epidermidis was significantly decreased by approximately four to five orders of magnitude in both Mg- and Mg₄₅Zn₅Ca-coated samples after seven days compared to the control. The osteoblast viability was within the tolerance threshold of 70% stated in DIN EN ISO 10993-5:2009-10 for Mg (~80%) but not for Mg₄₅Zn₅Ca (~25%). Accordingly, Mg-coated titanium was identified as a promising candidate for an implant material with antibacterial properties and low cytotoxicity levels. The approach of exploiting fast corrosion contrasts with existing methods, which have generally focused on reducing corrosion.     

Mini-review: Antimicrobial peptides and enzymes as promising candidates to functionalize biomaterial surfaces

Biomaterial-associated infections remain a serious concern in modern healthcare. The development of materials that can resist or prevent bacterial attachment constitutes a promising approach to dealing with this problem. Antimicrobial peptides (AMPs) and enzymes have been recognized as promising candidates for the new generation of antimicrobial surfaces. AMPs have been the focus of great interest in recent years owing to a low propensity for developing bacterial resistance, broad-spectrum activity, high efficacy at very low concentrations, target specificity, and synergistic action with classical antibiotics. Biofilm-dispersing enzymes have been shown to inhibit biofilm formation, detach established biofilm, and increase biofilm susceptibility to other antimicrobials. This review critically examines the potential of these protein-like compounds for developing antibacterial coatings by reporting their immobilization into different substrata using different immobilization strategies.     

Analysis of long-term mechanical grooming on large-scale test panels coated with an antifouling and a fouling-release coating

Long-term grooming tests were conducted on two large-scale test panels, one coated with a fluorosilicone fouling-release (FR) coating, and one coated with a copper based ablative antifouling (AF) coating. Mechanical grooming was performed weekly or bi-weekly using a hand operated, electrically powered, rotating brush tool. The results indicate that weekly grooming was effective at removing loose or heavy biofilm settlement from both coatings, but could not prevent the permanent establishment of low-profile tenacious biofilms. Weekly grooming was very effective at preventing macrofouling establishment on the AF coating. The effectiveness of weekly grooming at preventing macrofouling establishment on the FR coating varied seasonally. The results suggest that frequent mechanical grooming is a viable method to reduce the fouling rating of ships’ hulls with minimal impact to the coating. Frequent grooming could offer significant fuel savings while reducing hull cleaning frequencies and dry dock maintenance requirements.     

Biofouling and barnacle adhesion data for fouling‐release coatings subjected to static immersion at seven marine sites

Little is known about the performance of fouling‐release coatings at different geographical locations. An investigation was designed to measure the differences in biofouling and biofouling adhesion strength on three known silicone formulations and an epoxy control at seven static immersion sites located in California, Florida, Hawaii, Hong Kong, India, Italy and Singapore. The study found that whilst the relative performance of the coatings was similar at each site, there were statistically significant differences in the type and intensity of fouling that developed on the coatings and in barnacle adhesion strength among sites. The results emphasize the importance of evaluating potential coatings at more than one static immersion site.     

Development of silver-containing austenite antibacterial stainless steels for biomedical applications Part I: microstructure characteristics,mechanical properties and antibacterial mechanisms

The as-quenched (AQ) microstructure of the Ag-containing alloys was found to be essentially a mixture of austenite (γ) and Ag phases. The Ag phase precipitates had a face-centered-cubic structure and lattice parameter a = 4.09 Å. When the alloy contained Ag ≥0.2 wt%, the mechanical properties were slightly enhanced because of the precipitate strengthening by the Ag phase precipitates. Moreover, the Ag-containing alloys exhibited ductile fracture after tensile testing. The results of an antibacterial test revealed that the Ag phase precipitates play a key role in the antibacterial mechanism of Ag-containing alloys: Ag⁺ ions released from the Ag phase precipitates can kill bacteria. It is suggested that as AISI 316L alloy has an Ag content ≥0.2 wt%, it will have excellent antibacterial properties against both Staphylococcus aureus and Escherichia coli, with an antibacterial rate of nearly 100%.     

Variation in adhesion strength of Balanus eburneus,crassostrea virginica and hydroides dianthus to fouling‐release coatings

This study compared the shear adhesion strength of barnacles, oysters and tubeworms on eight RTV 11‐based silicone fouling‐release coatings containing different silicone oil additives. It was found that adhesion strength differed among species and coating types. In most cases, oysters and tubeworms had higher adhesion strengths than barnacles. Barnacle adhesion strength was reduced on all coatings containing oil additives; however, this was not generally true for oysters and tubeworms. The difference in the adhesion strength among the three organisms tested in this study emphasizes the importance of understanding the fundamental interaction between marine invertebrate adhesives and the substratum.     

Antibacterial Activity and Drug Release of Chitosan Sponge Containing Doxycycline Hyclate

The purpose of the present study was to develop and characterize the chitosan sponges loading with doxycycline hyclate and their antibacterial activities. The pore density of chitosan sponge prepared with freeze drying technique was increased as the higher concentrated chitosan solution was used. The sponge prepared from 10% w/w of the chitosan solution and crosslinking with glutaraldehyde solution was utilized for loading with doxycycline hyclate. The drug release and sustainable antibacterial activity of fabricated sponge were assessed using dissolution test and agar diffusion test, respectively. Drug release from non-crosslinked sponge into phosphate buffer pH7.4 was slower than that from crosslinked sponge since the former could absorb the medium and form gel to retard the initial drug diffusion. Sustainable antibacterial activity of developed sponge was evident against S. aureus and E. coli. In conclusion, the in vitro release profile and antibacterial efficiency indicated that doxycycline hyclate could be sustained using chitosan sponge.     

New insights into developing antibiofouling surfaces for industrial photobioreactors

The biofouling formation of the marine microalga Nannochloropsis gaditana on nontoxic surfaces was quantified on rigid materials, both coated (with fouling release coatings and nanoparticle coatings) and noncoated, to cover a wide range of surface properties from strongly hydrophobic to markedly hydrophilic under conditions similar to those prevailing in outdoor massive cultures of marine microalgae. The effect of seawater on surfaces that presented the best antibiofouling properties was also evaluated. The adhesion intensity on the different surfaces was compared with the predictions of the biocompatibility theories developed by Baier and Vogler using water adhesion tension (τ⁰) as the quantitative parameter of surface wettability. For the most hydrophobic surfaces, τ⁰ ≤ 0, the microalgae adhesion density increased linearly with τ⁰, following the Baier's theory trend. However, for the rest of the surfaces, τ⁰ ≥ 0, a tendency toward minimum adhesion was observed for amphiphilic surfaces with a τ⁰ = 36 mJ/m², a value close to that which minimizes cell adhesion according to Vogler's theory. The understanding and combination of the two biocompatibility theories could help to design universal antibiofouling surfaces that minimize the van der Waals forces and prevent foulant adsorption by using a thin layer of hydration.     

Biological succession on silicone fouling‐release surfaces: Long‐term exposure tests in the harbour of ischia,Italy

A static test site was set up in the Harbour of Ischia (Gulf of Naples, Italy) to investigate the antifouling effectiveness of newly developed non‐polluting coatings. Two‐year exposure experiments were performed on sets of panels coated with silicone‐based coatings, and results were compared both to sets of panels coated with toxic agents, and non‐toxic epoxydic compounds. Abiotic factors, strength of adhesion of the temporal dynamics of succession of foulers were analyzed throughout the period of immersion. Brown algae constantly represented the “border point”; between the early community, dominated by sume, micro‐ and macroalgae, and the late community, mainly represented by bryozoans and molluscs, as well as polychaetes, sponges and tunicates. Brown algae, such as Ectocarpus siliculosus, tunicates (mainly Botryllus schlossen) and polychaetes (Hydroides elegans, Pileolaria pseudomilitaris) were demonstrated to be key species, triggering the community and influencing its development. Light was the main abiotic factor discriminating the community on the two sides of panels exposed to different irradiances. The best performing coatings (silicone easy release coatings without additives) substantially influenced community structure, shifting it to the earliest stages of colonization. Silicone coatings proved to be unsuitable for colonization by organisms typical of mature communities, due to their low energy surfaces. The results of the present paper demonstrate that silicone coatings technology represents an alternative to the use of biocidal antifouling paints.     

青环海蛇抗菌肽Hc-CATH的分子设计及药效毒理优化

为获得分子量小、毒性低的抗感染多肽药物先导分子,以来源于青环海蛇的cathelicidin家族抗菌肽Hc-CATH为模板,设计了长度分别为16和15个氨基酸残基的改造体Hc-16和Hc-15,并通过CCK8实验、最小抑菌浓度 (Minimal inhibitory concentration,MIC) 实验、ELISA实验和生物膜干涉技术 (Bio-layer interferometry,BLI),对其进行毒性、抗菌活性、抗炎活性及LPS中和活性筛选。结果显示,两种改造体中,Hc-16对包括临床耐药菌在内的病原体具有广谱抗菌活性,最小抑菌浓度仅为4.69 μg/mL。同时抑制了LPS诱导的炎症因子TNF-α、IL-6的表达,显著降低感染诱发的炎症反应及细胞毒性。此外,构效关系研究表明C-、N-两端的苯丙氨酸在Hc-16抗菌抗炎活性中起着至关重要的作用。综上,Hc-16改造肽相比原模板具有更高的抗菌抗炎活性、更低的毒性以及更小的分子量,因而具有成本低、更好的成药性优势和较好的临床应用价值。     

Nano silver entrapped in phospholipids membrane: Synthesis,characteristics and antibacterial kinetics

Abstract

The antimicrobial property of stabilized silver nanoparticles (AgNPs) with phospholipid membrane was investigated on both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial strains. The influence of phospholipid concentrations on antibacterial kinetics actions of AgNPs was studied with two different methodologies in order to understand the bactericidal and bacteriostatic effects. The bacterial inactivation of synthesized AgNPs fitted well to the Chick-Watson model with a high regression coefficient, R² > 0.91. The antibacterial properties of AgNPs depend on the particle size, stabilizer and lecithin concentrations. Only the stabilized AgNPs that have the K_lec/Ag values of 1 and 2 presented the inhabitation zone, while unstabilized AgNPs agglomerated quickly, settled on the wells and did not diffuse in agar. In addition, the specific coefficient of lethality depends on the lecithin concentration. An increase in lecithin concentration caused multilayer creation on the AgNPs' surface and reduced the release of AgNPs which led to low bacterial killing rate.     

Mechanical aspects of silicone coatings for hard foulant control

Barnacle release mechanisms and the durability of silicone coatings have been studied. Release studies were performed on both transparent, single‐layer silicone coatings and duplex silicone coatings. The release forces of pseudobarnacles (epoxied studs) and Chesapeake Bay barnacles (Balanus improvisus) were measured with a pull‐off (tension) tester; modes of release were revealed in video recordings of the separation process from transparent coatings on glass. Scratch tests with 0.8 mm spherically‐tipped diamond provided a measure of durability (tear resistance). Release forces from both coatings decreased as coating thickness increased. Both pseudobarnacles and barnacles separated by a peeling process, although differences in peeling modes were seen. The durability of coatings increased with increasing coating thickness. Release behavior is discussed in terms of a fracture mechanic's model for pull‐off separation, and the differences in adhesion between barnacles and pseudobarnacles are described.     

Characterization and functional study of a Cecropin‐like peptide from the Chinese oak silkworm,Antheraea pernyi

In present study, a Cecropin‐like peptide from Antheraea pernyi (ApCec) was cloned and characterized. The full‐length ApCec cDNA encoded a protein with 64 amino acids including a putative 22‐amino‐acid signal peptide, a 4‐amino‐acid propeptide, and a 38‐amino‐acid mature peptide. ApCec gene was highly expressed in Malpighian tubules of A. pernyi after induction for 24 h by Escherichia coli in PBS. Pro‐ApCec (including propeptide and mature peptide) and M‐ApCec (just mature peptide) were synthesized chemically and analyzed by HPLC and mass spectroscopy. The antibacterial activity of M‐ApCec is more potent than pro‐ApCec against E. coli K12 or B. subtilus in both minimum inhibitory concentration and inhibition zone assays. Hemolytic assay results showed M‐ApCec possessed a low cytotoxicity to mammalian cells. The secondary structure of M‐ApCec forms α‐helical structure, shown by circular dichroism spectroscopy. Transmission electron microscopy analysis suggested that M‐ApCec killed bacteria by disrupting bacterial cell membrane integrity. Our results indicate ApCec may play an important role in defending from pathogenic bacteria in A. pernyi, and it may be as a potential candidate for applications in antibacterial drug development and agriculture.     

Peptoid microsphere coatings: The effects of helicity,temperature, pH,and ionic strength

Peptoids are peptidomimetic oligomers that predominantly harness similarities to peptides for biomimetic functionality. They have potential for use in biomedical applications and biosensors due to resistance to proteolytic degradation and low immunogenicity. The incorporation of chiral, aromatic side chains in the peptoid sequence allows for the formation of distinct secondary structures and self-assembly into supramolecular assemblies, including microspheres. Peptoid microspheres can be coated onto substrates for potential use in biosensor technologies, tissue engineering platforms, and drug-delivery systems. In order to be useful for these applications, the peptoid coatings must be robust under physiological conditions. In this study, we report the effects of various conditions on the peptoid microsphere coatings, including (i) helicity, (ii) temperature, (iii) pH, and (iv) ionic strength. These studies show that microsphere size decreases with increasing peptoid helicity and the positively charged side chains are positioned on the outside of the microspheres. The peptoid microsphere coatings are robust under physiological conditions but degrade in acidic conditions (pH < 7) and at low ionic strengths (<150 μM).     

Drag-reducing riblets with fouling-release properties: development and testing

The manufacture and preliminary testing of a drag-reducing riblet texture with fouling-control properties is presented. The commercial fouling-release product Intersleek® 1100SR was modified to manufacture riblet-textured coatings with an embossing technology. Hydrodynamic drag measurements in a Taylor–Couette set-up showed that the modified Intersleek® riblets reduced drag by up to 6% compared to a smooth surface. Barnacle settlement assays demonstrated that the riblets did not substantially reduce the ability of Intersleek® 1100SR to prevent fouling by cyprids of Balanus amphitrite. Diatom adhesion tests revealed significantly higher diatom attachment on the riblet surface compared to smooth Intersleek® 1100SR. However, after exposure to flow, the final cell density was similar to the smooth surface. Statically immersed panels in natural seawater showed an increase of biofilm cover due to the riblets. However, the release of semi-natural biofilms grown in a multi-species biofilm culturing reactor was largely unaffected by the presence of a riblet texture.     

Ciprofloxacin: review on developments in synthetic,analytical, and medicinal aspects

In the current practices of antiinfective therapy, ciprofloxacin is a very popular fluoroquinolone having a broad spectrum of activity and diverse therapeutic prospects. The reasons for its wide use include multiresistant pathogens susceptible only to ciprofloxacin. The available clinical evidence suggests the potentially enhanced efficacy of this drug in the treatment of various community acquired and nosocomial infections, e.g. respiratory tract, urinary tract, and skin infections and sexually transmitted diseases. As compared to other agents of its class, the pharmacokinetic profile of ciprofloxacin demonstrates equivalent or greater bioavailability, higher plasma concentrations, and increased tissue penetration, as reflected in the greater volume of distribution. Various molecular modifications of this drug have been made to further improve its characteristics. Several methods of analytical determination of ciprofloxacin and its metabolites in biological fluids employing various techniques have been reported. The present article is focused on the synthetic development, pharmacotherapeutic, and analytical evaluation vistas of ciprofloxacin.     

Callinectin, an Antibacterial Peptide from Blue Crab, Callinectes sapidus, Hemocytes

This paper describes the isolation of an approximately 3.7 kDa, basic, antibacterial peptide (designated callinectin), which represents the major antibiotic activity in blue crab, Callinectes sapidus, hemocytes. A single-step purification using low-pressure cation-exchange chromatology yielded a highly purified (>95%) peptide. Purity was confirmed by C₄ reverse-phase high-performance liquid chromatography (RP-HPLC), native gel electrophoresis, sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), capillary electophoresis, and mass spectral analysis. The partial amino acid sequence obtained via Edman degradation revealed no significant homology to other reported peptides in the Basic Local Alignment Search Tool (BLAST) program database. Received April 21, 1998; accepted July 3, 1998.     

Temporal and spatial variations in macrofouling of silicone fouling‐release coatings

Nontoxic, low surface free energy silicone coatings having reduced biofouling adhesion strength have been developed as an alternative to antifouling paints. Silicone coatings permit macrofouling to adhere; however, fouling can be removed easily by water pressure or light scrubbing. One of the current methods used to evaluate the performance of non‐toxic silicone fouling‐release coatings relies heavily on fouling coverage. The organismal community structure as well as total coverage can affect the ease of fouling removal from these coatings. This paper explores fouling coverage and organismal adhesion over time. Long‐term fouling coverage data were collected at four sites (in Massachusetts, Hawaii and Florida) using static immersion panels coated with silicone and oil‐amended silicone systems. Inter‐site differences in fouling coverage and community structure were observed for each coating. Intra‐site variation and temporal change in coverage of fouling was minimal, regardless of coating formulation. The extent of coverage was affected by the duration of immersion and the local environmental conditions; these factors may also have an impact on the foul‐release capability of the silicone coatings. Organismal adhesion data was collected in Hawaii and Florida. These adhesion measurements were used as a tool to discriminate and rank fouling release coatings.     

Making thin polymeric materials, including fabrics, microbicidal and also water-repellent

A procedure is developed and validated for making a non-functionalized polyolefin fabric/film highly bactericidal and fungicidal which involves a free-radical grafting of maleic anhydride, followed by an attachment of polyethylenimine (PEI) and its subsequent N-alkylation. Separately, cotton fabric coated with a micron layer of a hydrophobic polymer using hot-filament chemical vapor deposition is rendered markedly hydrophobic; if this coating is preceded by immobilization of N-alkyl-PEI, the fabric becomes both water-repellent and bactericidal.