Electroless controllable growth of ZnO films and their morphology-dependent antimicrobial properties

Enhanced photoelectrochemical water splitting using carbon cloth functionalized with ZnO nanostructures via polydopamine assisted electroless deposition

ZnO nanorods (ZnO-nr) have been widely studied as a promising nanomaterial for photoelectrochemical water splitting. However, almost all prior studies employed planar electrodes. Here, we investigated the performance of ZnO nanorods on a fibrous carbon cloth (CC) electrode, which offers a larger surface area for functionalization of photocatalysts. ZnO nanorods and Ni nanofilm were deposited on carbon cloth substrates for investigation as the photoanode and cathode of a photoelectrochemical water splitting setup, respectively. The use of polydopamine in the electroless deposition of ZnO ensured a uniform distribution of nanorods that were strongly adherent to the microfiber surface of the carbon cloth. Compared to ZnO nanorods grown on planar ITO/glass substrates, the CC-based ZnO photoanodes exhibited smaller onset potentials (1.1 VRHEvs. 1.8 VRHE), ∼40× larger dark faradaic currents at 1.23 VRHE and 5.5×-9× improvement in photoconversion efficiencies. Ni/CC cathodes were also found to exhibit a lower overpotential@10 mA cm-2 than Ni/Cu by 90 mV. The photocurrent obtained from the ZnO-nr/CC anode was highly stable across an hour and the peak current decreased by only 5% across 5 cycles of illumination, compared to 72% for the planar ZnO-nr/ITO anode. However, the response of the CC-based setups to changes in the illumination conditions was slower, taking hundreds of seconds to reach peak photocurrent, compared to tens of seconds for the planar electrodes. Using cyclic voltammetry, the double-layer capacitance of the electrodes was measured, and it was shown that the increased efficiency of the ZnO-nr/CC anode was due to a 2 order of magnitude increase in electrochemically active sites provided by the copious microfiber surface of the carbon cloth.

Review of Antimicrobial Nanocoatings in Medicine and Dentistry: Mechanisms of Action, Biocompatibility Performance, Safety, and Benefits Compared to Antibiotics

This review discusses topics relevant to the development of antimicrobial nanocoatings and nanoscale surface modifications for medical and dental applications. Nanomaterials have unique properties compared to their micro- and macro-scale counterparts and can be used to reduce or inhibit bacterial growth, surface colonization and biofilm development. Generally, nanocoatings exert their antimicrobial effects through biochemical reactions, production of reactive oxygen species or ionic release, while modified nanotopographies create a physically hostile surface for bacteria, killing cells via biomechanical damage. Nanocoatings may consist of metal nanoparticles including silver, copper, gold, zinc, titanium, and aluminum, while nonmetallic compounds used in nanocoatings may be carbon-based in the form of graphene or carbon nanotubes, or composed of silica or chitosan. Surface nanotopography can be modified by the inclusion of nanoprotrusions or black silicon. Two or more nanomaterials can be combined to form nanocomposites with distinct chemical or physical characteristics, allowing combination of different properties such as antimicrobial activity, biocompatibility, strength, and durability. Despite their wide range of applications in medical engineering, questions have been raised regarding potential toxicity and hazards. Current legal frameworks do not effectively regulate antimicrobial nanocoatings in matters of safety, with open questions remaining about risk analysis and occupational exposure limits not considering coating-based approaches. Bacterial resistance to nanomaterials is also a concern, especially where it may affect wider antimicrobial resistance. Nanocoatings have excellent potential for future use, but safe development of antimicrobials requires careful consideration of the "One Health" agenda, appropriate legislation, and risk assessment.

Adenosine Triphosphate-Responsive Glyconanorods through Self-Assembly of β-Cyclodextrin-Based Glycoconjugates for Targeted and Effective Bacterial Sensing and Killing

Polymer-based nanomaterials have exhibited promising alternative avenues to combat the globe challenge of multidrug-resistant bacterial infection. However, most of the reported polymeric nanomaterials have facially linear amphiphilic structures with positive net charges, which may lead to nonspecific binding, high hemolysis, and uncontrollable self-organization, limiting their practical applications. In this contribution, we report a one-dimensional glyconanorod (GNR) through self-assembly of well-defined β-cyclodextrin-based glycoconjugates (RMan) featuring hydrophobic carbon-based chains and amide rhodamines with an adenosine triphosphate (ATP)-recognition site and targeted and hydrophilic mannoses and positively net-charged ethylene amine groups. The GNRs show superior targeting sensing and killing for Gram-negative Escherichia coli (E. coli) dominantly through the multivalent recognition between mannoses on the nanorod and the lectin on the surface of E. coli. Moreover, red fluorescence was light on due to the hydrogen bonding between amide rhodamine and ATP. Benefiting from the designs, the GNRs are capable of possessing a higher therapeutic index and of encapsulating other antibiotics. They exhibit an enhanced effect against E. coli strains. Intriguingly, the GNRs displayed a more reduced hemolysis effect and lower cytotoxicity compared to that of ethylene glyco-modified nanorods. These results reveal that the glyconanomaterials not only feature superior and targeted bacterial sensing and antibacterial activity, but also better biocompatibility compared with the widely used PEG-covered nanomaterials. Furthermore, the in vivo studies demonstrate that the targeted and ATP-responsive GNRs complexed with antibiotics showed better treatment using a mouse model of abdominal sepsis following intraperitoneal E. coli infection. The present work describes a targeted and effective sensing and antibacterial platform based on glycoconjugates that have potential applications for the treatment of infections caused by pathogenic microorganisms.

Controllable synthesis of a sponge-like Z-scheme N,S-CQDs/Bi2MoO6@TiO2 film with enhanced photocatalytic and antimicrobial activity under visible/NIR light irradiation

Multifunctional photocatalytic surfaces for pollutant degradation and antimicrobial application are often in high demand, however they confront many challenges in charge transfer and light capture ability. In this work, a sponge-like N,S-CQDs/Bi₂MoO₆@TiO₂ film was constructed via hydrothermal technique aiming to solve above problems. As a result, the ternary film showed enhanced photocatalytic efficiency under visible and near-infrared (NIR) light, in which 85.8% and 44.6% of ciprofloxacin (CIP) were degraded after 240 min irradiation with visible and NIR light, respectively. Moreover, the composite film effectively realized photocatalytic sterilization of gram-positive B. subtilis and gram-negative E. coli under visible light irradiation. The bacterial colony decreased significantly from 7.56-log to 1-log cfu/mL after adding the ternary film within 1.5 h. The enhanced photocatalytic efficiency was closely related to both introduction of surface-functional N,S-CQDs and the construction of N,S-CQDs/Bi₂MoO₆@TiO₂ Z-scheme system, in which the transfer efficiency of photoinduced carriers and the light absorption property were significantly improved. We consider that the N,S-CQDs/Bi₂MoO₆@TiO₂ film is promising for the degradation of refractory pollutants and antimicrobial application under visible/NIR light irradiation. The relatively convenient recycling property and excellent photocatalytic performance of the N,S-CQDs/Bi₂MoO₆@TiO₂ film are beneficial for industrial applications.