Therapy of bacterial urinary tract infections (UTIs) and catheter associated urinary tract infections (CAUTIs) is still a great challenge because of the resistance of bacteria to nowadays used ...antibiotics and encrustation of catheters. Bacterial cellulose (BC) as a biocompatible material with a high porosity allows incorporation of different materials in its three dimensional network structure. In this work a low molecular weight chitosan (Chi) polymer is incorporated in BC with different concentrations. Different characterization techniques are used to investigate structural and optical properties of these composites. Radical scavenging activity test shows moderate antioxidant activity of these biocompatible composites whereas
in vitro
release test shows that 13.3% of chitosan is released after 72 h. Antibacterial testing of BC-Chi composites conducted on Gram-positive and Gram-negative bacteria causing UTIs and CAUTIs (
Escherichia coli
,
Pseudomonas aeruginosa
,
Klebsiella pneumoniae
) and encrustation (
Proteus mirabilis
) show bactericidal effect. The morphology analysis of bacteria after the application of BC-Chi shows that they are flattened with a rough surface, with a tendency to agglomerate and with decreased length and width. All obtained results show that BC-Chi composites might be considered as potential biomedical agents in treatment of UTIs and CAUTIs and as a urinary catheter coating in encrustation prevention.
Bacterial cellulose-chitosan composite with antibacterial and moderate antioxidant activity for potential UTI/CAUTI treatment and catheter coating in encrustation prevention.
This work is the continuation and refinement of already published communications based on PET/EG nanocomposites prepared by in situ polymerization
. In this study, nanocomposites based on ...poly(ethylene terephthalate) with expanded graphite were compared to those with functionalized graphite sheets (GO). The results suggest that the degree of dispersion of nanoparticles in the PET matrix has important effect on the structure and physical properties of the nanocomposites. The existence of graphene sheets nanoparticles enhances the crystallization rate of PET. It has been confirmed that in situ polymerization is the effective method for preparation nanocomposites which can avoid the agglomeration of nanoparticles in polymer matrices and improve the interfacial interaction between nanofiller and polymer matrix. The obtained results have shown also that due to the presence of functional groups on GO surface the interactions with PET matrix can be stronger than in the case of exfoliated graphene (EG) and matrix.
Low-temperature plasma was used to improve the surface and adhesive properties of wood. The pre-treatment of wood surfaces using radio-frequency (RF) discharge plasma is attractive for various wood ...applications, mainly because of the high efficiency and low production cost of the process. In addition, a significant increase in the polar component of the wood surface energy, which is associated with the presence of acid–base interactions (electron donor–acceptor bonds), after modification by RF discharge plasma was identified. The treatment of wood by RF plasma exhibited an aging effect, with the modified surface never recovering its initial hydrophobic state. Indeed, the enhancement of the wettability of wood is necessary for promoting better adhesion with water-based adhesives and coatings, which is currently the subject of ongoing study.
•Beech wood was treated by eco-friendly discharge plasma to improve adhesion.•The surface free energy of beech wood increased significantly due to plasma effect.•The hydrophobic recovery during aging was not leading to the initial state.•The enhancement of the wettability of beech wood led to the adhesion improvement.
It was shown that controlled degradation of poly-(
R)-3-hydroxybutyrate (PHB) can be achieved by alcoholysis with two types of alcohol in the presence of a catalyst. PHB oligomers terminated with ...free hydroxyl groups were prepared in this way. Molecular weight of the prepared samples was studied with three methods: SEC analysis with polystyrene calibration, SEC analysis using universal calibration, and viscometry. The data lead to the conclusion that SEC analysis using polystyrene calibration is a suitable method for monitoring degradation. The degradation proceeds by random chain scission and the molecular weight was decreased by almost two orders of magnitude depending on the alcoholysis conditions. The crystallinity and melting temperature,
T
m, of PHB after alcoholysis, investigated by differential scanning calorimetry (DSC) show the independence of crystallinity on molecular weight and a decrease in
T
m with decreased molecular weight. Time dependence of mechanical properties of selected samples (mechanical ageing) reveals that mechanical properties change with time for degraded samples in a similar way as for the parent polymer.
The electrochemical modification of carbon nanotube films (buckypapers) in three different electrolytes consisting of two acids and a basic solvent at very low concentrations was studied. The ...electrolysis was performed at 1
A up to a maximum of 12
h. Four different characterization techniques have been employed for assessing the effectiveness of the proposed process. The results presented are very encouraging for the development of electrochemical oxidation as the main surface modification method for carbon nanotubes. It was found that the use of nitric acid electrolyte leads to scalable and controllable oxidation as compared to the basic electrolyte which was also effective but appeared to damage the graphitic structure of nanotubes during longer treatments.
Bacterial infection and their resistance to known antibiotics delays wound healing. In this study, nanochitosan dots (nChiD) produced by gamma irradiation have been encapsulated in bacterial ...cellulose (BC) polymer matrix to study the antibacterial potentials of these nanocomposites and their possible usage in wound healing treatment (scratch assay). Detailed analyses show that nChiDs have disc-like shape and average diameter in the range of 40 to 60 nm depending of the applied dose. All nChiDs as well as BC-nChiD nanocomposites emit green photoluminescence independently on the excitation wavelengths. The new designed nanocomposites do not have a cytotoxic effect; antioxidant analysis shows their moderate radical scavenging activity whereas antibacterial properties show significant growth inhibition of strains mostly found in difficult-to-heal wounds. The obtained results confirm that new designed BC-nChiD nanocomposites might be potential agent in wound healing treatment.
Display omitted
•New innovative approach for wound healing treatment•Photoactive nanochitosan dots produced by gamma irradiation•Encapsulation of nanochitosan dots in bacterial cellulose•Nanochitosan dots/bacterial cellulose nanocomposite as moderate antioxidant agent•Nanochitosan dots/bacterial cellulose nanocomposite as strong bactericidal agent
Correction for 'Gamma ray assisted modification of carbon quantum dot/polyurethane nanocomposites: structural, mechanical and photocatalytic study' by Milica Budimir
et al.
,
RSC Adv.
, 2019,
9
, ...6278-6286.
In recent years, water pollution and contamination had become a major threat to the ecosystem. However, the use of nanostructured materials has been proven as a very promising approach in the ...treatment of polluted water. The present study reports the results of the gamma ray-assisted modification of hydrophobic carbon quantum dot (hCQD)/polyurethane nanocomposites for photocatalytic degradation of organic dyes. Different characterization methods were applied to investigate the influence of the different doses of gamma irradiation (1, 10 and 200 kGy) on the physical and chemical properties of nanocomposites (morphology, chemical content, mechanical properties, wettability, and potential for singlet oxygen generation). Surface morphology and mechanical properties analyses showed that gamma rays induced insignificant changes in the structure of nanocomposites, but the potential for singlet oxygen generation increased significantly. Here we also explore, in detail, the photocatalytic properties of gamma-ray modified hCQDs/polyurethane nanocomposites. UV-vis analysis showed that the removal efficiency of the rose bengal dye reached up to 97% for the nanocomposite irradiated with the dose of 200 kGy.
The present study reports the results of the gamma ray-assisted modification of hydrophobic carbon quantum dots (hCQDs)/polyurethane nanocomposites for photocatalytic degradation of organic dyes.
Due to controversial reports concerning antibacterial activity of different graphene based materials it is very important to investigate their antibacterial action on a wide range of Gram-positive ...and Gram-negative bacteria. In this paper we have investigated the structure induced phototoxic antibacterial activity of four types of graphene based materials: graphene oxide (GO), graphene quantum dots (GQDs), carbon quantum dots (CQDs) and nitrogen doped carbon quantum dots (N-CQDs). Antibacterial activity was tested on 19 types of bacteria. It is found that nanometer-size CQDs and N-CQDs are the most potent agents whereas micrometer-size GO has very poor antibacterial activity. Electron paramagnetic resonance measurements confirmed photodynamic production of singlet oxygen for all types of used quantum dots. Detailed analysis has shown that N-CQDs are an excellent photodynamic antibacterial agent for treatment of bacterial infections induced by
Enterobacter aerogenes
(
E. aerogenes
),
Proteus mirabilis
(
P. mirabilis
),
Staphylococcus saprophyticus
(
S. saprophyticus
),
Listeria monocytogenes
(
L. monocytogenes
),
Salmonella typhimurium
(
S. typhimurium
) and
Klebsiella pneumoniae
.
Antibacterial potentials of four graphene based nanomaterials are tested on a wide range of bacteria.
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