Sustained Antibacterial Effect Research Articles

The precipitate structure of copper-based antibacterial and antiviral agents enhances their longevity for kitchen use

The transmission of bacteria through cooking surfaces, the handles of hot plates, and cookware that is not cleaned frequently can pose a problem. In this study, a copper ion-based mixed solution (CBMS) containing only inorganic ions with controlled acidity was assessed as a new antibacterial and antiviral agent. We analysed the structure of the precipitates, and various deposits measuring a few micrometres were observed on the substrates. We have defined these deposits as strongly bonded scaly copper dispersion (SBSCD) structures.The antibacterial copper component of the liquid agent changed over time after application; this mechanism appears to be responsible for the maintenance of antibacterial performance.CBMS demonstrates high safety for the human body and can be applied to stainless steel materials used in kitchens and tables. It exhibits a sustained antibacterial effect over time, and its antibacterial properties can be continuously maintained.

Techno-functional properties of active film based on guar gum-propolis and its application for “Nanguo” pears preservation

Guar gum (GG) composite films, incorporating the ethanolic extract of propolis (EEP), were prepared and subjected to a comprehensive investigation of their functional characteristics. The addition of EEP resulted in a discernible enhancement in the opacity, moisture barrier capacity, and elongation at break. Incorporating EEP led to a noteworthy increase in the total phenolic and total flavonoid content of the films, resulting in superior antioxidant capacity upon GG-EEP films. Remarkably, the addition of 5 % EEP yielded noteworthy outcomes, manifesting in a DPPH radical scavenging rate of 47.60 % and the ABTS radical scavenging rate of 94.87 %, as well as FRAP and cupric reducing power of 331.98 mmol FeSO4-7H2O kg−1 and 56.95 μg TE mg−1, respectively. In addition, GG-EEP films demonstrated antifungal effect against Penicillium expansum and Aspergillus niger, along with a sustained antibacterial effect against Escherichia coli and Staphylococcus aureus. GG-EEP films had superior inhibitory ability against Gram-positive bacteria than Gram-negative bacteria. Crucially, GG-EEP composite films played a pivotal role in reducing both lesion diameter and depth, concurrently mitigating weight loss and firmness decline during the storage period of “Nanguo” pears. Therefore, GG-EEP composite films have the considerable potential to serve as advanced and effective active packaging materials for food preservation.

Nanoapatite-Loaded κ-Carrageenan/Poly(vinyl alcohol)-Based Injectable Cryogel for Hemostasis and Wound Healing.

Immediate control of excessive bleeding and prevention of infections are of utmost importance in the management of wounds. Cryogels have emerged as promising materials for the rapid release of medication and achieving hemostasis. However, their quick release properties pose the challenge of exposing patients to high concentrations of drugs. In this study, hybrid nanocomposites were developed to address this issue by combining poly(vinyl alcohol) and κ-carrageenan with whitlockite nanoapatite (WNA) particles and ciprofloxacin, aiming to achieve rapid hemostasis and sustained antibacterial effects. A physically cross-linked cryogel was obtained by subjecting a blend of poly(vinyl alcohol) and κ-carrageenan to successive freezing-thawing cycles, followed by the addition of WNA. Furthermore, ciprofloxacin was introduced into the cryogel matrix for subsequent evaluation of its wound healing properties. The resulting gel system exhibited a 3D microporous structure and demonstrated excellent swelling, low cytotoxicity, and outstanding mechanical properties. These characteristics were evaluated through analytical and rheological experiments. The nanocomposite cryogel with 4% whitlockite showed extended drug release of 71.21 ± 3.5% over 21 days and antibacterial activity with a considerable growth inhibition zone (4.19 ± 3.55 cm). Experiments on a rat model demonstrated a rapid hemostasis property of cryogels within an average of 83 ± 4 s and accelerated the process of wound healing with 96.34% contraction compared to the standard, which exhibited only ∼78% after 14 days. The histopathological analysis revealed that the process of epidermal re-epithelialization took around 14 days following the skin incision. The cryogel loaded with WNAs and ciprofloxacin holds great potential for strategic utilization in wound management applications as an effective material for hemostasis and anti-infection purposes.

AgNPs-Modified Polylactic Acid Microneedles: Preparation and In Vivo/In Vitro Antimicrobial Studies.

To prepare polylactic acid microneedles (PLAMNs) with sustained antibacterial effect to avoid skin infection caused by traditional MNs-based biosensors. Silver nanoparticles (AgNPs) were synthesized using an in-situ reduction process with polydopamine (PDA). PLAMNs were fabricated using the hot-melt method. A series of pressure tests and puncture experiments were conducted to confirm the physicochemical properties of PLAMNs. Then AgNPs were modified on the surface of PLAMNs through in-situ reduction of PDA, resulting in the formation of PLAMNs@PDA-AgNPs. The in vitro antibacterial efficacy of PLAMNs@PDA-AgNPs was evaluated using agar diffusion assays and bacterial liquid co-culture approach. Wound healing and simulated long-term application were performed to assess the in vivo antibacterial effectiveness of PLAMNs@PDA-AgNPs. The MNs array comprised 169 tiny needle tips in pyramidal rows. Strength and puncture tests confirmed a 100% puncture success rate for PLAMNs on isolated rat skin and tin foil. SEM analysis revealed the integrity of PLAMNs@PDA-AgNPs with the formation of new surface substances. EDS analysis indicated the presence of silver elements on the surface of PLAMNs@PDA-AgNPs, with a content of 14.44%. Transepidermal water loss (TEWL) testing demonstrated the rapid healing of micro-pores created by PLAMNs@PDA-AgNPs, indicating their safety. Both in vitro and in vivo tests confirmed antibacterial efficacy of PLAMNs@PDA-AgNPs. In conclusion, the sustained antibacterial activity exhibited by PLAMNs@PDA-AgNPs offers a promising solution for addressing skin infections associated with MN applications, especially when compared to traditional MN-based biosensors. This advancement offers significant potential for the field of MN technology.

Antibacterial photodynamic properties of silver nanoparticles-loaded curcumin composite material in chitosan-based films

In order to cope with the increasingly severe food contamination and safety problems, a powerful sterilization of food packaging material is urgently needed. Chitosan (CS) has potential applications in food packaging due to its good film-forming properties, but its antibacterial activity is not sufficient to meet the needs in practical applications. Silver nanoparticles (AgNPs) have the problem of weak immediate antibacterial activity as a broad-spectrum antibacterial agent. Therefore, in this study, AgNPs@GA@Cur-POTS (AGCP) composite antibacterial system was prepared by combining AgNPs with antibacterial photodynamic therapy using gallic acid (GA) as a reducing agent, curcumin (Cur) as a photosensitizer and perfluorosilane (POTS) for surface modification. The results showed that AGCP could produce a large number of reactive oxygen species under blue light irradiation, killing >90 % of E. coli and S. aureus within 2 h. Subsequently, the composite film of CS loaded with AGCP (CS/AGCP) was prepared by the flow-delay method. The CS/AGCP composite film exhibited excellent barrier properties and antioxidant activity, while its antibacterial rates against E. coli and S. aureus reached 98.44 ± 1.27 % and 99.11 ± 0.24 %, respectively, while the OD630 values of the two groups of bacteria treated with it showed no significant increase in incubation for up to 132 h, exhibiting remarkable and sustained antibacterial effects. Taken together, this work will provide a new strategy for antibacterial food packaging.

TEMPO-oxidized nanofibrillated cellulose as potential carrier for sustained antibacterial delivery

Designing a suitable, cost-effective nanocarrier with an ability to capture and deliver antibiotics for restricting microbial spread remains an unmet need. A simple two-stepped strategy involving citric acid-induced hydrolysis of cellulose pulp (NFC) followed by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) mediated oxidation to obtain carboxylated nano fibrillated cellulose (TNFC-5) with high carboxyl content (1.12 mmol/g) has been explored. TNFC-5 so obtained was able to capture remarkable extent of antibiotics (drug loading (DL) > 40 % and entrapment efficiency (EE) >80 %) irrespective of their hydrophilicity as in, triclosan (hydrophobic) and ampicillin sodium (hydrophilic). In silico molecular docking study revealed the excess carboxyl content in nanocellulose imparted the strongest binding affinity to antibiotics via H-bonding. A slower and sustained release of triclosan was observed for TNFC-5 than that of NFC, reiterating the enhanced binding efficiency of the drugs with TNFC-5. Well-dispersed triclosan loaded TNFC-5 displayed sustained antibacterial activity against Escherichia coli and Staphylococcus aureus up to one week. Thus, TNFC-5 has been demonstrated as a green, cheap, and eco-friendly alternative to the other biodegradable nanocarriers for carrying antibiotics with high DL and EE, thereby reducing the wastage of expensive drugs while ensuring a sustained antibacterial effect. Our study established that the drug loaded nanofibers (TNFC-5) might act as a promising candidate to penetrate through biofilm for treating serious bacterial infections by retarding their growth and eventually eradicating bacterial colonies.

Near-infrared excited graphene oxide/silver nitrate/chitosan coating for improving antibacterial properties of titanium implants

To design and construct a graphene oxide (GO)/silver nitrate (Ag3PO4)/chitosan (CS) composite coating for rapidly killing bacteria and preventing postoperative infection in implant surgery. GO/Ag3PO4 composites were prepared by ion exchange method, and CS and GO/Ag3PO4 composites were deposited on medical titanium (Ti) sheets successively. The morphology, physical image, photothermal and photocatalytic ability, antibacterial ability, and adhesion to the matrix of the materials were characterized. The GO/Ag3PO4 composites were successfully prepared by ion exchange method and the heterogeneous structure of GO/Ag3PO4 was proved by morphology phase test. The heterogeneous structure formed by Ag3PO4 and GO reduced the band gap from 1.79 eV to 1.39 eV which could be excited by 808 nm near-infrared light. The photothermal and photocatalytic experiments proved that the GO/Ag3PO4/CS coating had excellent photothermal and photodynamic properties. In vitro antibacterial experiments showed that the antibacterial rate of the GO/Ag3PO4/CS composite coating against Staphylococcus aureus reached 99.81% after 20 minutes irradiation with 808 nm near-infrared light. At the same time, the composite coating had excellent light stability, which could provide stable and sustained antibacterial effect. GO/Ag3PO4/CS coating can be excited by 808 nm near infrared light to produce reactive oxygen species, which has excellent antibacterial activity under light.

Fabrication of Antifouling/Antimicrobial Polysulfonium‐Coated Surface Against Biofilms and Water Bacterial Contamination

Bacterial attachment and colonization on the surface have caused a severe threat to human healthcare. The development of surface coatings with high antibacterial activity and low toxicity is highly desired. Herein, a series of sulfonium‐containing polypeptoids with various structural motifs on the side chains is synthesized, which are efficiently grafted on the silicone surface via plasma and ultraviolet light treatment. The resulting coating demonstrates excellent antibacterial properties against both Gram‐positive and Gram‐negative bacteria, as well as a sustained antibacterial effect at ambient temperature for up to one week. Moreover, the coating exhibits excellent in vitro antibiofilm and protein resistance properties, as well as excellent hemo/biocompatibility. Further, by fabricating a decontamination system with the coated substrates, the obtained coating materials show high efficiency in bacterial decontamination of water, which has great potential for use in water disinfection systems. All these results suggest that prepared coating with dual antibacterial and antifouling properties has great potential in combating bacterial contamination.

Fabrication of Silver-Doped UiO-66-NH2 and Characterization of Antibacterial Materials

Metal-organic frameworks (MOFs) are highly crystalline inorganic-organic complexes formed from metal ions or metal clusters and multi-toothed organic ligands. MOFs have great potential for use in antibacterial materials in the biological, environmental, and food antimicrobial fields. They can act as a reservoir of metal ions, releasing them gradually and leading to a sustained antibacterial effect analogous to that proposed for metal oxide nanoparticles (NPs). Herein, UiO-66-NH2 as a type of MOF was first prepared by a facile solvothermal method and then loaded with Ag NPs to form a Ag/UiO-66-NH2 composite and the different materials were synthesized by controlling silver doping amount, which are then applied to an antibacterial test. Works on the synthesis of Ag/UiO-66-NH2 and its antibacterial test were not reported before. The synthesized materials were characterized using the field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), thermal gravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) techniques. The antibacterial activity of the Ag/UiO-66-NH2 was then assessed against E. coli (gram-negative bacteria) and Staphylococcus aureus (gram-positive bacteria), using the inhibition zone (ZIO) method and optical density (OD) method. The obtained results have shown that the introduction of Ag does not interfere with the crystallization of UiO-66-NH2. The FT-IR spectral profiles recorded for the UiO-66-NH2 samples fabricated under conditions of varying silver ion doping levels are similar to those recorded for UiO-66-NH2. The thermal stability of UiO-66-NH2 containing varying amounts of silver ions was lower than the thermal stability of UiO-66-NH2. However, under these conditions, the specific surface area and pore volume increased. The antibacterial performance of UiO-66-NH2 improved significantly following the process of silver ion doping. The best antibacterial performance was observed when the silver ion content was 4 wt.%. Overall, we synthesized a new nanocomposite material with broad-spectrum bacterial sterilization, which was easy to manufacture.

Sustained antibacterial coating with graphene oxide ultrathin film combined with cationic surface-active agents in a wet environment

Antimicrobial surfactants contained in mouthrinse have excellent efficacy, but are not retained on the tooth surface (are rinsed away) due to their low water resistance and thus do not exhibit sustained antibacterial activity. We have developed a new coating method using graphene oxide (GO) that retains the surfactant on the tooth surface even after rinsing with water, thus providing a sustained antibacterial effect. Ultra-thin films of GO and an antimicrobial agent were prepared by (1) applying GO to the substrate surface, drying, and thoroughly rinsing with water to remove excess GO to form an ultrathin film (almost a monolayer, transparent) on the substrate surface, then (2) applying antimicrobial cationic surface active agents (CSAAs) on the GO film to form a composite coating film (GO/CSAA). GO/CSAA formation was verified by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and ζ-potential and contact angle measurements. GO/CSAA was effective at inhibiting the growth of oral pathogens for up to 7 days of storage in water, and antibacterial activity was recovered by reapplication of the CSAA. Antibacterial GO/CSAA films were also formed on a tooth substrate. The results suggest that GO/CSAA coatings are effective in preventing oral infections.

Core-Sheath Electrospun Nanofibers Based on Chitosan and Cyclodextrin Polymer for the Prolonged Release of Triclosan.

This work focuses on the manufacture of core-sheath nanofibers (NFs) based on chitosan (CHT) as sheath and cyclodextrin polymer (PCD) as core and loaded with triclosan (TCL). In parallel, monolithic NFs consisting of blended CHT-PCD and TCL were prepared. Nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier Transform Infrared spectroscopy (FTIR). SEM displayed the morphology of NFs and the structure of the nanowebs, while TEM evidenced the core-sheath structure of NFs prepared by coaxial electrospinning. The core diameters and sheath thicknesses were found dependent on respective flow rates of both precursor solutions. Nanofibers stability and TCL release in aqueous medium were studied and correlated with the antibacterial activity against Staphylococcus aureus and Escherichia coli. Results showed that the release profiles of TCL and therefore the antibacterial activity were directly related to the type of nanofibers. In the case of monolithic nanofibers, the NFs matrix was composed of polyelectrolyte complex (PEC formed between CHT and PCD) and resulted in a prolonged release of TCL and a sustained antibacterial effect. In the case of core-sheath NFs, the PEC was formed only at the core-sheath interface, leading to less stable NFs and therefore to a faster release of TCL, and to a less extended antibacterial activity compared to monolithic ones.

Microwave synthesis of graphene oxide decorated with silver nanoparticles for slow-release antibacterial hydrogel

Inorganic antibacterial materials, graphene oxide (GO), and silver nanoparticles (AgNPs) are considered promising antibacterial materials due to their excellent biocompatibility, broad-spectrum antibacterial properties, and non-drug resistance. In this manuscript, Branched polyethyleneimine (PEI) stabilized GO-AgNPs antibacterial nanocomposites (PEI-GO-AgNPs) were integrated with Pluronic F127 to develop a slow-release antibacterial hydrogel for more stable and sustained antibacterial effect. Antibacterial mechanism has been proposed according to the experimental observation. The synergistic effect of PEI-GO-AgNPs resulted in the death of bacteria and molds. PEI reduced the aggregation of PEI-GO-AgNPs nanomaterials to capture/adsorb pathogens effectively and increased the contact between Ag and pathogens. The sharp edges of the GO nanosheets can physically cut the bacterial cells then the Ag can interact with the cell membrane, disrupting the permeability and material transport of the cell membrane. The antibacterial test showed that the antibacterial rate of 10 μg/mL PEI-GO-AgNPs against bacteria (Escherichia coli) and molds (Candida albicans) are 99.86% and 99.94%. It is worth to mention that the PEI-GO-AgNPs were well dispersed in normal saline within a week. In addition, PEI-GO-AgNPs released 72% Ag from the prepared Pluronic F127 hydrogel within one week.

Bioactive and functional biodegradable packaging films reinforced with nanoparticles

Compared to traditional synthetic packaging materials, biopolymer packaging films are biodegradable and environmentally-friendly. However, most raw materials failed to serve alone as food packaging due to their poor mechanical and barrier properties, which limits their wide application. Nanomaterials have drawn great interest in recent years due to their extraordinary properties, making them advantageous in food packaging and nanocomposite applications. Naturel biopolymers including starch, cellulose, protein, and chitosan can be transferred into nanoscale via different treatments. Specifically, these nanoparticles can render significant barrier properties as well as mechanical, optical, catalytic, antimicrobial, and other functional properties when used in packaging. This paper provides the new technological advances in the mechanical and barrier reinforcing effects of nanoparticles on biopolymer-based packaging films. Bio-active and functional food packaging films combined with active compounds loaded nanoparticles are also summarized, which are regarded as ideal materials to maintain the nutritive quality and safety of packaged food. • The nanoparticles (NPs) can be introduced into biopolymer films as fillers. • The addition of NPs significantly enhanced barrier and mechanical properties of films. • The active components in films render sustained antibacterial and antioxidant effects. • The bioploymer films provide new substitutes to conventional packaging materials.

Anti-bacterial and anti-microbial aging effects of resin-based sealant modified by quaternary ammonium monomers

ObjectivesPit and fissure sealant is used in the prevention of dental caries. However, commercial pit and fissure sealant lacks persistent antibacterial properties. Dimethylaminododecyl methacrylate (DMADDM) was added to pit and fissure sealants to give it sustainable antibacterial properties and anti-microbial aging properties. MethodsResin-based sealant was used as a control. Novel sealants were made with DMADDM. Atomic force microscope observation, curing depth, cytotoxicity, lactic acid measurement, hardness and microleakage were measured. Saliva-derived biofilms were grown on sealants. Biofilm metabolic activity, lactic acid production and biomass accumulation were measured. ResultsIncorporating DMADDM did not increase the cytotoxicity or change the physical properties when the mass fraction of the DMADDM was 2.5–10%. The modification decreased the amount of bacterial biofilm, metabolic activity, lactic acid production and exopolysaccharide (EPS) in the saliva biofilms. It also provided anti-microbial aging properties. ConclusionThe incorporation of DMADDM improved the antibacterial and anti-microbial aging effects of the material. It demonstrated a sustained antibacterial effect. The antibacterial and anti-microbial aging modification might be a potential choice for future clinical applications to inhibit dental caries, especially for children at high caries risk. Clinical SignificanceThe antibacterial and anti-microbial aging modification might be a potential choice for future clinical applications to prevent dental caries, especially for individuals at high caries risk.

Sustained Antibacterial Effect of Levofloxacin Drug in a Polymer Matrix by Hybridization With A Layered Double Hydroxide

AbstractThe immobilization of antimicrobial drugs can be used to expand the application of antibacterial properties to consumer products. The purpose of this study was to stabilize an antimicrobial agent, levofloxacin (LVX), for sustained antibacterial activity by immobilizing the drug molecules in a layered double hydroxide (LDH) and embedded in a polyurethane substrate. As-prepared MgAl-LDH was calcined at 400°C and reconstructed with LVX for intercalation. The X-ray diffraction patterns and cross-sectional transmission electron microscopy images showed lattice expansion along the crystallographic c axis upon LVX intercalation, suggesting successful loading of the drug. Fourier-transform infrared spectra revealed that the structure of LVX was well preserved between LDH layers. Elemental analysis indicated that the loading capacity of LVX in the hybrid was 41.7%. Bacterial-colony forming inhibitory assay on Bacillus subtilis exhibited ~100% antibacterial activity of both LVX alone and LVX-LDH hybrid (LL). To determine sustainability of antibacterial activity by the hybrid, either LVX alone or LL hybrid was loaded in the polyurethane (PU) substrate for which antibacterial activity was evaluated before and after immersion in a phosphate-buffered saline for 3 days. The LVX-composited PU showed a dramatic decrease in antibacterial activity, down to 0% after buffer treatment; LL-composited PU still contained antibacterial activity (~34% of colony suppression) after phosphate-buffered saline immersion.

Sustained Antibacterial Effect and Wear Behavior of Quaternary Ammonium Contact-Killing Dental Polymers after One-Year of Hydrolytic Degradation

This study intended to investigate the long-term antibacterial effect, mechanical performance, and surface topography of new anticaries dental composites. While most artificial aging studies of dental resins lasted for 30–90 days, this study prolonged the water-aging to one year to be more clinically relevant. The base resin was loaded with dimethylaminohexadecyl methacrylate (DMAHDM) at 3 or 5 wt.% and nano-sized amorphous calcium phosphate (NACP) at 20 wt.%. Composites were subjected to one-year water storage and wear. Following water aging, samples were evaluated for flexural strength, elastic modulus, and microbiological assays. Biofilm plate counting method, metabolic assay, colorimetric quantification of lactic acid, and Baclight bacterial viability assay were measured after one year. Topography changes (ΔRa, ΔRq, ΔRv, ΔRt) were examined after wear and observed by scanning electron microscopy. Biofilm assays and topography changes data were analyzed via one-way ANOVA and Tukey’s tests. Mechanical properties and normalized data were verified using a t-test. The flexural strength values for the formulations that contained 5% DMAHDM-20% NACP, 3% DMAHDM, and 5% DMAHDM were reduced significantly (p < 0.05) in relation to the baseline but the values were still above the ISO standards. No significant differences were observed between the groups concerning the topography changes, except for the ΔRt, where there was a significant increase in the 5% DMAHDM-20% NACP group. All the groups demonstrated robust biofilm-inhibition, with slightly reduced antibacterial properties following water aging. The aged samples reduced the total microorganisms, total streptococci, and mutans streptococci by 1.5 to 3-log, compared to the experimental control. The new formulations containing DMAHDM and NACP were able to sustain the antibacterial performance after one-year of aging. Mechanical properties and surface topography were slightly affected over time.

Safety, efficacy, and analysis of key parameters after prophylactic administration of a sustained-release formulation of azithromycin in lung cancer surgery.

The current use of prophylactic antibiotics for lung cancer surgery requires modification in aging individuals with impaired lung function. A sustained-release formulation of azithromycin (AZM-SR) could help resolve some of these challenges with its sustained antibacterial and anti-inflammatory effects. The aim of this study was to examine the safety and efficacy of AZM-SR in lung cancer surgery as well as its anti-inflammatory effect. Fifty patients were included in the study, and AZM-SR was administered 1 day prior to the surgery. The clinical course, including postoperative complications, was monitored, and the concentration of AZM, bacterial culture, and inflammatory cytokine levels of resected lung specimens were evaluated. No side effects related to AZM-SR were observed. Five cases of postoperative pneumonia (10%) were observed; technical issues were involved in 3 cases. All patients recovered well. Four cases showed positive bacterial culture upon lung tissue examination; however, this was not significantly correlated with postoperative complications. A negative correlation was observed between AZM concentration in lung tissue and interleukin-6 (IL-6) expression. Prophylactic utilization of AZM-SR in lung cancer surgery seems feasible. The anti-inflammatory effect of AZM might contribute additional beneficial effects in the perioperative management of lung cancer surgery.

Antibacterial Collagen Composite Membranes Containing Minocycline.

Collagen membranes have been used as bioresorbable barrier membranes in guided tissue/bone regeneration. However, the collagen membranes currently used in clinics lack an active antibacterial function, although infection at surgical sites presents a realistic challenge for guided tissue/bone regeneration. In this study, we successfully prepared novel and advanced collagen composite membranes from collagen and complexes of heparin and chelates of minocycline and Ca2+ ions. These membranes were characterized for chemical structures, morphology, elemental compositions and tensile strength. Invitro release studies were conducted to evaluate the release kinetics of minocycline from these membranes. Agar disk diffusion assays were used to assess their sustained antibacterial capability against model pathogenic bacteria Staphylococcus aureus. The chemical and physical characterization confirmed the successful synthesis of minocycline-loaded collagen composite membranes, namely NCCM-1 and NCCM-2. Both membranes had weaker tensile strength as compared with commercial collagen membranes. They achieved sustained release of minocycline for at least 4 weeks in simulated body fluid (pH 7.4) at 37°C. Moreover, both membranes demonstrated potent sustained antibacterial effects against Staphylococcus aureus. These results suggested that the advanced collagen composite membranes containing minocycline can be exploited as novel guided tissue regeneration membranes or wound dressing by providing additional antibacterial functions.

Highly Sustained Release of Bactericides from Complex Coacervates.

Materials for preventing harmful bacterial contamination attract widespread interest in areas that include healthcare, home/personal care products, and crop protection. One approach to achieving this functionality is through the sustained release of antibacterial compounds. To this end, we show how putty-like complex coacervates, formed through the association of poly(allylamine hydrochloride) (PAH) with pentavalent tripolyphosphate (TPP) ions, can provide a sustained antibacterial effect by slowly releasing bactericides. Using triclosan (TC) as a model bactericide, we demonstrate that, through their dispersion in the parent PAH solution with nonionic surfactants, hydrophobic biocides can be efficiently and predictably encapsulated within PAH/TPP coacervates. Once encapsulated, the bactericide can be released over multiple months, and the release rates can be readily tuned by varying the bactericide and surfactant compositions used during encapsulation. Through this release, the PAH/TPP coacervates provide sustained bactericidal activity against model Gram-positive and Gram-negative bacteria (Staphylococcus aureus and Escherichia coli) grown under a nutrient-rich condition over at least two weeks. Thereafter, though some partial activity persists after one month, the release slows down and the bactericide-eluting coacervates lose their efficacy. Overall, we show that bactericide release from easy-to-prepare complex coacervates can provide a pathway to sustained disinfection.

Manufacture of pH- and HAase-responsive hydrogels with on-demand and continuous antibacterial activity for full-thickness wound healing

A kind of “intelligent” antibacterial dressing–A-HA/HA-ADH/SS hydrogel was in situ formed quickly via dynamic covalent bonds cross-linking between aldehyde hyaluronic acid (A-HA), adipic acid dihydrazide graft hyaluronic acid (HA-ADH) and sisomicin sulfate (SS). FT-IR, SEM and rheological results displayed that the hydrogels were successfully prepared. The hydrogels had good optical transmittance, injectability, self-healing ability, cytocompatibility, antioxidant activity and hemostatic performance which were beneficial to observe the wound healing condition and provide a good healing environment for wounds. In addition, the hydrogels showed a pH- and HAase- dependent degradability, which allowed them to release more SS at infected wound and then exert on-demand and sustained antibacterial effect against S. aureus and E. coli. The results of wound healing and histological examination revealed that these hydrogels have a good therapeutic effect in the full-thickness mouse skin defect wound. Thus, the hydrogels are expected to be used as potential wound dressings to improve wound healing.