Sustainable Synthesis of Ionic Liquid-Functionalized Zinc Oxide Nanosheets (IL@ZnO): Evaluation of Antibacterial Potential Activity for Biomedical Applications

Synthesis and Characterization of Naproxen Intercalated Zinc Oxide Stacked Nanosheets for Enhanced Hepatoprotective Potential

Liver diseases pose a significant global health burden, with limited therapeutic options for chronic cases. Zinc oxide (ZnO) nanomaterials have emerged as promising candidates for hepatoprotection due to their antioxidant, anti-inflammatory, and regenerative properties. However, their potential remains hampered by insufficient drug loading and controlled release. The current study explores the intercalation of Naproxen (Nx), a potent anti-inflammatory and analgesic drug, within ZnO stacked nanosheets (SNSs) to address these limitations. Herein, an easy and solution-based synthesis of novel Nx intercalated ZnO SNSs was established. The obtained Nx intercalated ZnO SNSs were encapsulated with poly(vinyl acetate) (PVA) to make them biocompatible. The synthesized biocomposite was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR), which confirm the successful synthesis and intercalation of Nx within the ZnO SNSs. The obtained outcomes showed that the configuration of ZnO nanosheets was altered when Nx was introduced, resulting in a more organized stacking pattern. An in vivo investigation of mice liver cells unveiled that the Nx intercalated ZnO SNss had increased hepatoprotective properties. The study's results provide valuable insights into using Nx intercalated ZnO SNss for targeted drug delivery and improved treatment effectiveness, particularly for liver-related illnesses.

3D-Printed Multifunctional Ag/CeO2/ZnO Reinforced Hydroxyapatite-Based Scaffolds with Effective Antibacterial and Mechanical Properties

Conventional three-dimensional (3D)-printed hydroxyapatite (HA)-based constructs have limited utility in bone tissue engineering due to their poor mechanical properties, elevated risk of microbial infection, and limited pore interconnectivity. 3D printing of complex multiple components to fabricate fully interconnected scaffolds is a challenging task; here, in this work, we have developed a procedure for fabrication of printable ink for complex systems containing multinanomaterials, i.e., HAACZ (containing 1 wt % Ag, 4 wt % CeO2, and 6 wt % ZnO) with better shear thinning and shape retention properties. Moreover, 3D-printed HAACZ scaffolds showed a modulus of 143.8 GPa, a hardness of 10.8 GPa, a porosity of 59.6%, effective antibacterial properties, and a fully interconnected pore network to be an ideal construct for bone healing. Macropores with an average size of ∼469 and ∼433 μm within the scaffolds of HA and HAACZ and micropores with an average size of ∼0.6 and ∼0.5 μm within the strut of HA and HAACZ were developed. The distribution of fully interconnected micropores was confirmed using computerized tomography, whereas the distribution of micropores within the strut was visualized using Voronoi tessellation. The water contact angle studies revealed the most suitable hydrophilic range of water contact angles of ∼71.7 and ∼76.6° for HA and HAACZ, respectively. HAACZ scaffolds showed comparable apatite formation and cytocompatibility as that of HA. Antibacterial studies revealed effective antibacterial properties for the HAACZ scaffold as compared to HA. There was a decrease in bacterial cell density for HAACZ from 1 × 105 to 1.2 × 103 cells/mm2 against Gram-negative (Escherichia coli) and from 1.9 × 105 to 5.6 × 103 bacterial cells/mm2 against Gram-positive (Staphylococcus aureus). Overall, the 3D-printed HAACZ scaffold resulted in mechanical properties, comparable to those of the cancellous bone, interconnected macro- and microporosities, and excellent antibacterial properties, which could be utilized for bone healing.

Electropolymerization of Pyrrole-Tailed Imidazolium Ionic Liquid for the Elaboration of Antibacterial Surfaces

A strategy was developed to prepare antibacterial surfaces by electropolymerization of a pyrrole-functionalized imidazolium ionic liquid bearing an halometallate anion. The objective was to combine the antibacterial efficiency of polypyrrole (PPy) with those of the ionic liquid's components (cation and anion). For this, N-(1-methyl-3-octylimidazolium)pyrrole bromide monomer [PyC₈MIm]Br was synthesized and coordinated to ZnCl₂ affording [PyC₈MIm]Br-ZnCl₂. The antibacterial properties of [PyC₈MIm]Br-ZnCl₂ monomer were evaluated against Escherichia coli and Staphylococcus aureus by measurement of the minimum inhibitory concentration (MIC) values. This monomer presents higher activity against S. aureus (MIC = 0.098 μmol·mL^-1) than against E. coli (MIC = 2.10 μmol·mL^-1). Mixtures of pyrrole and the pyrrole-functionalized ionic liquid [PyC₈MIm]Br-ZnCl₂ were then used for the electrodeposition of PPy films on Fluorine-doped tin oxide (FTO) substrates. The concentration of pyrrole was fixed to 50 mM, while the concentration of [PyC₈MIm]Br-ZnCl₂ was varied from 5 to 100 mM. The efficient incorporation of the imidazolium cation and zinc halometallate anion into the films was confirmed by X-ray photoelectron spectroscopy (XPS) measurements. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements confirmed the homogeneity of the different films with structures that depend on the [PyC₈MIm]Br-ZnCl₂ concentration. The films' thickness determined by profilometry varies only slightly with the [PyC₈MIm]Br-ZnCl₂ concentration from 7.4 μm at 5 mM to 8.9 μM at 100 mM. The films become more hydrophilic with an increase of [PyC₈MIm]Br-ZnCl₂ concentration with water contact angles varying from 47° at the lowest concentration to 32° at the highest concentration. The antibacterial activities of the different PPy films were determined both by the halo inhibition method and by the colony forming units (CFUs) counting method over time against Gram-positive S. aureus and Gram-negative E. coli bacteria. Films obtained by incorporation of [PyC₈MIm]Br-ZnCl₂ showed excellent antibacterial properties, at least two times higher than those of neat PPy, validating our strategy. Furthermore, a comparison of the antibacterial properties of the films obtained using the same [PyC₈MIm]Br-ZnCl₂ concentration (50 mM) evidenced much better activity against Gram-positive (no bacterial survival within 5 min) than against Gram-negative bacteria (no bacterial survival within 3 h). Finally, the antibacterial performances over time could be tuned by the concentration of the employed pyrrole-functionalized ionic liquid monomer. Against E. coli, using 100 mM of [PyC₈MIm]Br-ZnCl₂, the bacteria were totally killed within a few minutes, using 50 mM, they were killed after 2 h while using 10 mM, about 20% of bacteria survived even after 6 h.

Nanomaterial-Based Zinc Ion Interference Therapy to Combat Bacterial Infections

Pathogenic bacterial infections are the second highest cause of death worldwide and bring severe challenges to public healthcare. Antibiotic resistance makes it urgent to explore new antibacterial therapy. As an essential metal element in both humans and bacteria, zinc ions have various physiological and biochemical functions. They can stabilize the folded conformation of metalloproteins and participate in critical biochemical reactions, including DNA replication, transcription, translation, and signal transduction. Therefore, zinc deficiency would impair bacterial activity and inhibit the growth of bacteria. Interestingly, excess zinc ions also could cause oxidative stress to damage DNA, proteins, and lipids by inhibiting the function of respiratory enzymes to promote the formation of free radicals. Such dual characteristics endow zinc ions with unparalleled advantages in the direction of antibacterial therapy. Based on the fascinating features of zinc ions, nanomaterial-based zinc ion interference therapy emerges relying on the outstanding benefits of nanomaterials. Zinc ion interference therapy is divided into two classes: zinc overloading and zinc deprivation. In this review, we summarized the recent innovative zinc ion interference strategy for the treatment of bacterial infections and focused on analyzing the antibacterial mechanism of zinc overloading and zinc deprivation. Finally, we discuss the current limitations of zinc ion interference antibacterial therapy and put forward problems of clinical translation for zinc ion interference antibacterial therapy.