Tien Thanh Nguyen

The growing prevalence of antibiotic-resistant infections highlights the need for antimicrobial surfaces that do not rely on conventional drug release.

In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films embedded with silver nanoparticles were fabricated to investigate their antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Inspired by the nanoscale topographies of natural antibacterial surfaces, such as dragonfly and cicada wings, microstructured pillars were introduced onto the polymer surface to enhance its bactericidal activity by increasing the effective contact area. Surface morphology was characterised using scanning electron microscopy (SEM), including higher-magnification imaging of micropillar surfaces, while energy-dispersive X-ray spectroscopy confirmed the presence of silver. Higher-magnification SEM revealed nanoscale surface features on the micropillars, attributed to embedded or surface-associated silver nanoparticles. Antibacterial performance was evaluated using confocal laser scanning microscopy with live/dead staining. The PVDF-HFP/Ag films exhibited a significant reduction in bacterial viability, particularly against S. aureus (reducing viability to 0.6% ± 1.1%), while showing moderate activity against E. coli (41.0% ± 3.7% viability). While the fabricated micropillars (~5 µm) are larger than bacterial cells and unlikely to induce direct mechanical rupture, they increase surface interaction. To further investigate the theoretical antibacterial mechanism of scaled-down features, finite element analysis (FEA) was performed to model the mechanical interaction between bacterial cells and nanostructured pillars. The simulation results indicated localised stress concentrations that could compromise bacterial membrane integrity, suggesting a possible mechanobactericidal contribution if the microstructures are further reduced to the nanoscale, in addition to the primary biochemical effects of silver nanoparticles. FEA results do not aim to explain the experimentally observed antibacterial performance and should be interpreted only as a conceptual investigation. These findings demonstrate the potential of bio-inspired PVDF-HFP/Ag films as antibacterial materials for food packaging and related applications, subject to future comprehensive toxicity and quantitative microbiological evaluations.

The rise of antibiotic-resistant bacteria, particularly Escherichia coli and Staphylococcus aureus, poses a critical threat to public health and food safety, as these pathogens are increasingly detected in processed foods. This study evaluates the antibacterial potential of inorganic particle/polymer composites by incorporating silver (Ag) nanoparticles and zinc oxide (ZnO) microstructures into poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films with micropillar surfaces. PVDF-HFP@Ag and PVDF-HFP@ZnO films were fabricated using solvent casting and hydrothermal growth methods, respectively, and their microstructures were characterized by FESEM, EDX, and AFM analyses. Antibacterial activity was tested against E. coli (ATCC 11303) and S. aureus (ATCC 25923) using a Live/Dead™ BacLight™ staining protocol and confocal laser scanning microscopy (CLSM). PVDF-HFP@Ag films reduced S. aureus viability to 0.6% ± 1.1% and E. coli to 41% ± 3.7%, while PVDF-HFP@ZnO films showed enhanced efficacy against E. coli (1.36% ± 0.98%) and suppressed S. aureus (3.8% ± 6%). These effects are attributed to synergistic mechanisms, including membrane disruption, ROS generation, and metal ion toxicity. The findings demonstrate the potential of these composites as scalable, non-antibiotic antimicrobial materials for food-contact surfaces and active packaging, offering a promising strategy to mitigate antimicrobial resistance and foodborne pathogens.

Chronic wounds often result in multiple infections with various kinds of bacteria and uncontrolled wound exudate, resulting in several healthcare issues. Advanced medicated nanofibres prepared by electrospinning have gained much attention for their topical application on infected chronic wounds. The objective of this work is to enhance the critical variables of ciprofloxacin-loaded polycaprolactone-silk sericin (PCL/SS-PVA-CIP) nanofibre production via the process of electrospinning. To examine the antibacterial effectiveness of PCL/SS-PVA-CIP nanocomposites, the material was tested against P. aeruginosa and S. aureus. The combination of PCL/SS-PVA-CIP exhibited potent inhibitory properties, with the most effective concentrations of ciprofloxacin (CIP) being 3 μg/g and 7.0 μg/g for each bacterium, respectively. The biocompatibility was evaluated by conducting cell reduction and proliferation studies using the human epidermal keratinocyte (HaCaT) cells and human gingival fibroblasts (HGFs) in vitro cell lines. The PCL/SS-PVA-CIP showed good cell compatibility with HaCaT and HGF cells, with effective proliferation even at antibiotic doses of up to 7.0 μg/g. The drug release effectiveness of the nanocomposites was assessed at various concentrations of CIP, resulting in a maximum cumulative release of 76.5% and 74.4% after 72 h for CIP concentrations of 3 μg/g and 7 μg/g, respectively. In summary, our study emphasizes the possibility of combining silk sericin (SS) and polycaprolactone (PCL) loading with CIP nanocomposite for wound management.

Developing novel antibacterial strategies has become an urgent requisite to overcome the increasing pervasiveness of antimicrobial-resistant bacteria and the advent of biofilms. Aggregation-induced emission-based photosensitizers (AIE PSs) are promising candidates due to their unique photodynamic and photothermal properties. Bioengineering structure-inherent AIE PSs for developing thin film coatings is still an unexplored area in the field of nanoscience. We have adopted a synergistic approach combining plasma technology and AIE PS-based photodynamic therapy to develop coatings that can eradicate bacterial infections. Here, we loaded AIE PSs within biomimetic bacterium-like particles derived from a probiotic strain, Lactobacillus fermentum. These hybrid conjugates are then immobilized on polyoxazoline-coated substrates to develop a bioinspired coating to fight against implant-associated infections. These coatings could selectively kill Gram-positive and Gram-negative bacteria, but not damage mammalian cells. The mechanistic studies revealed that the coatings can generate reactive oxygen species that can rupture the bacterial cell membranes. The mRNA gene expression of proinflammatory cytokines confirmed that they can modulate infection-related immune responses. Thus, this nature-inspired design has opened a new avenue for the fabrication of a next-generation antibacterial coating to reduce infections and associated burdens.

Bacterial infections account for countless deaths globally. Antibiotics are the primary countermeasure; however, the alarming spread of antibiotic‐resistant strains necessitates alternative solutions. Silver and silver compounds have emerged as promising antibacterial agents. However, issues related to cytotoxicity and genotoxicity of silver remain concern. To overcome these challenges, this proposes an easy‐to‐control and straightforward method to synthesize novel Silver─gallium (Ag─Ga) nano‐amalgamated particles. Gallium liquid metal (GaLM) is used to facilitate the galvanic deposition of silver nanocrystals (Ag) on oxide layer. The GaLM not only serves as a carrier for silver through the galvanic replacement process, but also provides a controlled‐release mechanism for silver, in this way improving biocompatibility, reducing inflammation, and stimulating bone growth. Notably, Ag─Ga suspensions can be conveniently deposited by spray‐coating on a range of devices and material surfaces, effectively eliminating pathogenic bacteria with efficacy comparable to that of silver ions. In vivo studies in rat models affirm the antibacterial capabilities, especially against methicillin‐resistant Staphylococcus aureus and Escherichia coli, when placed on implants such as titanium rods and magnesium discs. Furthermore, Ag─Ga promotes bone matrix formation and collagen growth without eliciting an inflammatory response, indicating a major promise for coatings on a wide variety of biomedical devices and materials.

The use of synchrotron macro ATR-FTIR micro-spectroscopy to reveal the antibacterial mechanism of silver ions against S. aureus and P. aeruginosa.

The challenge of wound healing, particularly in patients with comorbidities such as diabetes, is intensified by wound infection and the accelerating problem of bacterial resistance to current remedies such as antibiotics and silver. One promising approach harnesses the bioactive and antibacterial compound C‐phycocyanin from the microalga Spirulina maxima. However, the current processes of extracting this compound and developing coatings are unsustainable and difficult to achieve. To circumvent these obstacles, a novel, sustainable argon atmospheric plasma jet (Ar‐APJ) technology that transforms S. maxima biomass into bioactive coatings is presented. This Ar‐APJ can selectively disrupt the cell walls of S. maxima, converting them into bioactive ultrathin coatings, which are found to be durable under aqueous conditions. The findings demonstrate that Ar‐APJ‐transformed bioactive coatings show better antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, these coatings exhibit compatibility with macrophages, induce an anti‐inflammatory response by reducing interleukin 6 production, and promote cell migration in keratinocytes. This study offers an innovative, single‐step, sustainable technology for transforming microalgae into bioactive coatings. The approach reported here has immense potential for the generation of bioactive coatings for combating wound infections and may offer a significant advance in wound care research and application.

In this study, we fabricated hierarchical structures on the surface of polyurethane acrylate (PUA) film and demonstrated that the film displays antibacterial properties. PUA resin was coated on a commercial porous anodized aluminum oxide (AAO) template and was UV-cured using nanoimprint lithography. This led to the formation of 150 nm diameter pillars on the surface of PUA film. Following this, zinc oxide structures were grown on the surface of this imprinted PUA sample using a hydrothermal method. The scanning electron microcopy and Fourier transform infrared spectroscopy results confirmed the presence of ZnO on the surface of the PUA film. The antibacterial behavior of the fabricated sample was demonstrated against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) as model bacteria. The results show that PUA film with 150 nm diameter pillars had moderate antibacterial properties against both S. aureus and P. aeruginosa. The presence of zinc oxide (ZnO) structures improved the film's antibacterial property to ∼100% against P. aeruginosa. However, the presence of ZnO structures on PUA film is shown to have no effect against S. aureus. This can be attributed to the shape and size of the fabricated ZnO structures.

Nanosized multi-drug delivery systems provide synergistic effects between drugs and bioactive compounds, resulting in increased overall efficiency and restricted side effects compared to conventional single-drug chemotherapy. In this study, we develop an amphiphilic heparin-poloxamer P403 (HP403) nanogel that could effectively co-load curcuminoid (Cur) and cisplatin hydrate (CisOH) (HP403@CisOH@Cur) via two loading mechanisms. The HP403 nanogels and HP403@CisOH@Cur nanogels were closely analyzed with ¹H-NMR spectroscopy, FT-IR spectroscopy, TEM, and DLS, exhibiting high stability in spherical forms. In drug release profiles, accelerated behavior of Cur and CisOH at pH 5.5 compared with neutral pH was observed, suggesting effective delivery of the compounds in tumor sites. In vitro studies showed high antitumor activity of HP403@CisOH@Cur nanogels, while in vivo assays showed that the dual-drug platform prolonged the survival time of mice and prevented tail necrosis. In summary, HP403@CisOH@Cur offers an intriguing strategy to achieve the cisplatin and curcumin synergistic effect in a well-designed delivery platform that increases antitumor effectiveness and overcomes undesired consequences caused by cisplatin in breast cancer treatment.