Chitosan (CS) and its derivatives have been applied extensively in the biomedical field owing to advantageous characteristics including biodegradability, biocompatibility, antibacterial activity and ...adhesive properties. The low solubility of CS at physiological pH limits its use in systems requiring higher dissolving ability and a suitable drug release rate. Besides, CS can result in fast drug release because of its high swelling degree and rapid water absorption in aqueous media. As a water-soluble derivative of CS, carboxymethyl chitosan (CMC) has certain improved properties, rendering it a more suitable candidate for wound healing, drug delivery and tissue engineering applications. This review will focus on the antibacterial, anticancer and antitumor, antioxidant and antifungal bioactivities of CMC and the most recently described applications of CMC in wound healing, drug delivery, tissue engineering, bioimaging and cosmetics.
TiO2–ZnO/Au ternary heterojunction nanocomposite was fabricated by producing TiO2 nanosheets first using solvent-thermal method followed by Au deposition and ZnO deposition respectively. The TiO2 ...nanosheets provide a relatively large surface area for the good dispersion of ZnO nanoparticles and Au particles and sufficient contact with the medium, which contribute to the excellent photocatalytic performances of TiO2–ZnO/Au heterojunction composite. The phases and structures, morphologies, surface and optical properties of the ternary heterojunction composite are well-characterized. Subsequently, the photocatalytic hydrogen generation of TiO2–ZnO/Au is evaluated under visible light irradiation. TiO2–ZnO/Au ternary heterojunction composite has efficient light absorption ability and excellent performances in photocatalytic hydrogen generation (1068 μmol/g under the irradiation of visible light for 4 h) and antibacterial properties (reaching 98.2%). TiO2–ZnO/Au ternary heterojunction nanocomposite has a large potential to be used in areas such as interior wall coating.
Aqueous dispersions of AgCu nanoparticles (NPs), with enhanced antibacterial efficacy, have been prepared through the catalyzed reduction of Cu ions by PVP/PVA-stabilized Ag nanoparticles at 85 °C. ...The effects of Cu concentration and heating time on NP morphology and antibacterial efficacy were investigated, using TEM, UV-Vis and FTIR spectroscopies, and antibacterial evaluations. The enhanced antibacterial performance of these NPs was correlated with Ag ion release. We propose a simple model of AgCu NP formation, and an enhanced antibacterial efficacy mechanism involving Ag ion release, in which AgCu NPs formation plays a role to control of Ag ion release.
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•AgCu nanoalloy prepared by heating Ag NPs stabilized by PVP-PVA in the presence of Cu ions at 85 °C.•AgCu nanoparticles possess enhanced antibacterial activity, associated with AgCu alloy formation.•Cu controls Ag ion release from AgCu NPs, and is correlated with enhanced antibacterial activity.•AgCu NP antibacterial mechanism attributed to Ag ion release from AgCu nanoalloy.
Chitosan (CH) was blended with poly vinyl alcohol (PVA) in different compositions to obtain biodegradable films (PVA90:CH10, PVA80:CH20, PVA70:CH30). Blends and neat polymer films (PVA100, CH100) ...were characterized for their thermal behavior, structural, mechanical and barrier properties as well as antimicrobial activity. Both polymers showed good compatibility, as demonstrated by FESEM images and thermal behavior. A reduction in crystallinity of the blend was observed as the chitosan content was increased. Moreover, chitosan addition strongly reduced the film stretchability while increased the film rigidity and resistance to fracture, mainly at 70:30 PVA:CH ratio. Additional advantages of chitosan incorporation to PVA films are the reduction of the UV-transmittance while providing antimicrobial properties.
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•Chitosan (CH) was blended with poly vinyl alcohol (PVA) to obtain biodegradable films.•CH reduced the extensibility of the PVA films, increasing the rigidity and strength.•CH presence in PVA provoked a reduction of the UV light transmission of the blends.•The incorporation of CH to PVA provides films with antimicrobial activity.•The blending of CH into PVA seems to be a strategy for food packaging products.
The fabrication of novel thin-film nanocomposite (TFN) membranes with superior flux, rejection as well as prolonged stability is being requested by membrane industries for saving energy and cost. In ...this regard, in the present research work we developed novel TFN membranes using amine-rich synthetic talc (NHST) nanosheets within diethylenetriamine (DETA) and trimesoyl chloride (TMC) monomers over a polydopamine (PDA) coating layer. Different concentrations (0.2–1 %) of NHST nanosheets are applied for the fabrication of TFN membranes and comparatively examined with a thin-film composite (TFC) membrane. In-situ synthesized NHST nanosheet phases are confirmed by several characterization techniques and results are explored in depth. All prepared membranes are well investigated to confirm the incorporation of NHST by several characterization techniques, like FE-SEM, ATR-FTIR, HR-TEM, XPS, PXRD, TGA, and contact angle. It is found that a small amount of NHST doping in the TFN layer considerably improved the performance in the form of permeability and rejection. The developed TFN membranes showed hydrophilic characteristics as confirmed by the contact angle. Water flux performance of TFN membranes was also observed comparatively higher than TFC membranes. Optimized NHST-PDT-TFN2 membrane with NHST concentration 0.5 % resulted in 98.96, 95.35, 93.83 and 21.66 % rejection for Na2SO4, MgSO4, CuSO4 and NaCl salts, respectively together with permeance up to 24.45, 22.72, 26.45 and 30.75 Lm−2h−1b−1. The present research finding concludes that the incorporation of a little quantity of NHST nanosheets in the TFN layer plays a unique potential role in the enhancement of flux and rejection of targeted mineral salts. Additionally, the NHST-PDT-TFN membranes revealed outstanding antibacterial properties signifying that contact with microorganisms does not affect the performance and sustains the fouling resistance. The antifouling study of the membranes concluded that the addition of nanomaterials has led to enhanced antifouling tendency and low irreversible fouling, improving the longevity of the membranes.
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•Aminofunctionlized synthetic talc nanosheets are used first time as TFN nanofillers.•PDA-coated TFC and TFN membranes were prepared by interfacial polymerization method.•The resultant novel NHST-PDT-TFN2 membrane exhibited the highest performance.•Prepared TFN membranes show excellent antifouling and antibacterial properties.
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•The Ti2Cu of corrosion activity is composed of a “micro-galvanic cell” with α-Ti.•The lamellar Ti2Cu increased the Cu ion release caused by more galvanic interface.•The antibacterial ...rate of L-Ti2Cu is 99.5 %, due to the rapid release of Cu ions.
The influence of morphology of the Ti2Cu phase on biological corrosion and antibacterial properties of Ti-Cu alloy was investigated by micro-galvanic corrosion. Elongated “micro-galvanic cells” were formed between lamellar Ti2Cu phase (L-Ti2Cu) and α-Ti matrix due to the different Volta potentials. The corrosion rate (Vcorr) of L-Ti2Cu was twice that of granular Ti2Cu phase (G-Ti2Cu) because lamellar Ti2Cu phase had more galvanic interface. The release of Cu2+ ions in L-Ti2Cu was 55 % higher than G-Ti2Cu, reaching 99.5 % of the antibacterial rate in L-Ti2Cu and providing a great potential in clinical application for dental implants.
The prevention and control of hospital-acquired infections remain a significant challenge worldwide, as textiles used in hospital wards are highly involved in transmission processes. This paper ...reports a new antibacterial medical fabric used to prepare hospital pillowcases, bottom sheets and quilt covers for controlling and reducing hospital-acquired infections.
The medical fabric was composed of blended yarns of staple polyester (PET) and degradable poly(3-hydroxybutyrate co-3-hydroxyvalerate) (PHBV)/polylactic acid (PLA) fibres, which were coated with polylactide oligomers (PLAO), which are environmentally friendly and safe antimicrobial agents with excellent thermal stability in high-temperature laundry. A clinical trial was conducted, with emphasis on the bacterial species that were closely related to the infection cases in the study hospital.
After 7 days of use, 94% of PET/PHBV/PLA-PLAO fabric retained <20 colony-forming units/100 cm2 of the total bacterial amount, meeting hygiene and cleanliness standards.
This study demonstrates the potential of fabrics containing polyhydroxyalkanoate oligomers as highly effective, safe and long-lasting antimicrobial medical textiles that can effectively reduce the incidence of hospital-acquired infections.
An improved Knoevenagel condensation yielded three α,β-unsaturated ketones whose photostability and antibacterial properties were evaluated.
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•Three dibenzylideneacetones were ...synthesized by an improved Knoevenagel reaction.•Compound 2 with -N(CH3)2 groups exhibits potential as a broad-spectrum UV filter.•Compounds 2 &3 show good antibacterial activity and are leads for new antibiotics.
A series of three symmetrical α,β-unsaturated ketones, namely, (1E,4E)-1,5-bis4-(methylthio)phenylpenta-1,4-dien-3-one, 1, (1E,4E)-1,5-bis4-(dimethylamino)phenylpenta-1,4-dien-3-one, 2, and (1E,4E)-1,5-bis4-(ethyl)phenyl penta-1,4-dien-3-one, 3, were synthesized in excellent yields (above 70%) and within a short reaction time (1 h), via an improved Knoevenagel condensation with acetyl acetone and substituted benzaldehydes. All the compounds were fully characterized by UV/Vis, IR, NMR and mass spectrometry. In addition, compound 1 was characterized by single crystal X-ray diffraction. The photostability of the prepared compounds was investigated in solvents of different polarity and proticity by exposure to simulated solar radiation. Three solvents were used, namely, ethyl acetate, dimethylsulfoxide and methanol. The change in UV absorption was monitored by a standard spectrophotometric method and photodegradation products were identified by 1H NMR. According to the results, 1 and 3 were not photostable, and suffered significant changes in their UV absorption spectra. Compound 2, on the other hand, was observed to be considerably photostable in the polar protic solvent methanol but less photostable in the polar aprotic solvent dimethylsulfoxide. All three compounds (1–3) photodegraded appreciably in the less polar aprotic solvent ethyl acetate. Therefore, their photostability is solvent dependent. The antibacterial activity of 1–3 was evaluated by means of the modified broth microdilution method against both gram-negative and gram-positive bacterial strains. Compounds 2 (methylated amine) and 3 (ethyl) have electron-releasing substituents and they were found to have excellent activity against all the tested bacteria. Thus, compounds 2 and 3 can be further explored as potential leads for the development of cheaper, safer, more effective and potent antibiotics against both gram-positive and gram-negative bacterial strains, and compound 2 is a good candidate for use in sunscreen formulations if dissolved in a polar solvent.
The influence of capping agents on silver nanoparticles (AgNPs) was investigated through a rapid and single-pot chemical reduction method. Four capping agents were tested: polyethylene glycol (PEG), ...ethylenediaminetetraacetic acid (EDTA), polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA). FTIR studies demonstrated that the formed AgNPs were properly encapsulated by their respective capping agents. Structural and morphological studies confirmed the following relative average particle sizes: PEG-AgNPs > EDTA-AgNPs > PVP-AgNPs > PVA-AgNPs. Optical absorption and photoluminescence studies showed, respectively, a greater absorption blue shift and greater emission intensity for the smaller capped particles. Zeta potential analysis of the PVA-AgNPs showed a value of -46.6 mV, indicating their high stability. The PVA-AgNPs were thus not only observed to be the smallest, most blue-shifted and most stable of the tested AgNPs, but also they displayed the highest antibacterial activity. The PVA-AgNPs were therefore applied as a localized surface plasmon resonance (LSPR)-based H sub(2)O sub(2) sensor, which is important because the detection of reactive oxygen species such as H sub(2)O sub(2) is of significance in the medical and environmental fields. The sensor based on the PVA-AgNPs successfully detected H sub(2)O sub(2) at concentrations as low as 10 super(-7) M. New biosensors using these NPs should thus find promising opportunities in a variety of fields.
Bimetallic nanoparticles of noble metals are of high interest in imaging, biomedical devices, including nanomedicine, and heterogeneous catalysis. Synthesis, properties, characterization, biological ...properties, and practical applicability of nanoparticles on the basis of platinum group metals and the coin metals Ag and Au are discussed, also in comparison with the corresponding monometallic nanoparticles. In addition to the parameters that are required to characterize monometallic nanoparticles (mainly size, size distribution, shape, crystallographic nature, surface functionalization, charge), further information is required for a full characterization of bimetallic nanoparticles. This concerns the overall elemental composition of a bimetallic nanoparticle population (ratio of the two metals) and the internal distribution of the elements in individual nanoparticles (e.g., the presence of homogeneous alloys, core–shell systems, and possible intermediate stages). It is also important to ensure that all particles are identical in terms of elemental composition, that is, that the homogeneity of the particle population is given. Macroscopic properties like light absorption, antibacterial effects, and catalytic activity depend on these properties. The currently available methods for a full characterization of bimetallic nanoparticles are discussed, and future developments in this field are outlined.
Bimetallic nanoparticles offer many possibilities beyond their constituents, that is, the pure metals. For instance, their imaging properties can be fine‐tuned, the antibacterial effects of silver can be changed by blending it with a second metal, and the performance in heterogeneous catalysis including electrocatalysis can be enhanced. The current concepts on synthesis and characterization are outlined.
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