Dual phototransformation of the pollutants methyl orange and Cr (VI) using phthalocyanine-cobalt ferrite based magnetic nanocomposites

Resveratrol-Encapsulated Glutathione-Modified Robust Mesoporous Silica Nanoparticles as an Antibacterial and Antibiofilm Coating Agent for Medical Devices

The emergence of various lethal bacterial infections and their adherence to medical devices are major public health concerns. The increased bacterial exposure and titer are accompanied by the inappropriate use of antibiotics that sometimes lead to antibiotic resistance, and therefore, a drug-free antibacterial approach is required. Several nanoparticles (NPs) have been developed as antibacterial and antibiofilm coating agents, which can overcome different drug resistance mechanisms by inhibiting the important processes related to bacterial virulence potential. However, developing safe and biocompatible nanomaterials (NMs) for these applications has remained a major challenge due to their poorly understood mechanism of action. In this work, biogenic silica NPs were modified with glutathione (GSH) to form GSH@SNP (∼80 ± 15 nm) for targeting the bacterial cell surface and biofilm. GSH@SNP was loaded with resveratrol to obtain Res_GSH@SNP (∼124 ± 15 nm) that enhances the antibacterial activity of the NPs against Staphylococcus aureus and Escherichia coli by ∼51 and ∼49%, respectively, compared to GSH@SNP. Res_GSH@SNP is responsible for binding to the bacterial cell surface receptors that interrupt the cell membrane potential, leading to reactive oxygen species (ROS) generation, membrane disruption, and DNA damage and eventually resulting in antibacterial activity. Moreover, the antibiofilm activity of Res_GSH@SNP has been found to result from the interaction of the NPs with the abundant carbohydrates present on the biofilm surface. To check the practical utility of Res_GSH@SNP, these were further evaluated as an antibacterial and antibiofilm coating agent for urinary catheters and were found to be effective even after multiple washes. Res_GSH@SNP has been found to exhibit ∼80 ± 1.4% cytocompatibility toward fibroblast NIH-3T3 cells. Overall, this study is expected to pave the way for the development of biocompatible NP-based coating agents for medical devices.

Synthesis and Characterization of Supermagnetic Nanocomposites Coated with Pluronic F127 as a Contrast Agent for Biomedical Applications

Nanomedicine has garnered significant interest owing to advances in drug delivery, effectively demonstrated in the treatment of certain diseases. Here, smart supermagnetic nanocomposites based on iron oxide nanoparticles (MNPs) coated with Pluronic F127 (F127) were developed for the delivery of doxorubicin (DOX) to tumor tissues. The XRD patterns for all samples revealed peaks consistent with Fe3O4, as shown by their indices (220), (311), (400), (422), (511), and (440), demonstrating that the structure of Fe3O4 did not change after the coating process. After loading with DOX, the as-prepared smart nanocomposites demonstrated drug-loading efficiency and drug-loading capacity percentages of 45 ± 0.10 and 17 ± 0.58% for MNP-F127-2-DOX and 65 ± 0.12 and 13 ± 0.79% for MNP-F127-3-DOX, respectively. Moreover, a better DOX release rate was observed under acidic conditions, which may be credited to the pH sensitivity of the polymer. In vitro analysis demonstrated the survival rate of approximately 90% in HepG2 cells treated with PBS and MNP-F127-3 nanocomposites. Furthermore, after treatment with MNP-F127-3-DOX, the survival rate decreased, confirming cellular inhibition. Hence, the synthesized smart nanocomposites showed great promise for drug delivery in liver cancer treatment, overcoming the limitations of traditional therapies.

Fabrication of copper phthalocyanine/reduced graphene oxide nanocomposites for efficient photocatalytic reduction of hexavalent chromium

Copper(II) phthalocyanine (CuPc) and non-peripheral octamethyl-substituted copper(II) phthalocyanine (N-CuMe₂Pc) were combined with reduced graphene oxide (rGO) via a precipitation method to form CuPc/rGO and N-CuMe₂Pc/rGO nanocomposites, respectively. CuPc nanorods are distributed on rGO, and N-CuMe₂Pc exists as nanorods and nanoparticles on rGO. The Cr(VI) removal ratio of N-CuMe₂Pc/rGO exposed in simulated sunlight is 99.0% with a fast photocatalytic reaction rate of 0.0320 min^-1, which is approximately 1.5 times faster than that of CuPc/rGO (0.0215 min^-1) and far surpasses that of pristine phthalocyanine and rGO. As an electron acceptor, rGO can suppress the recombination of photo-induced electron-hole pairs and also can provide a large surface area for Cr(VI) removal, both of which are beneficial to the reducing capacity of the nanocomposites. The higher removal efficiency of N-CuMe₂Pc/rGO compared with that of CuPc/rGO is attributed to the higher specific surface area, higher light harvesting, higher conductivity and more negative lowest unoccupied molecular orbital level of N-CuMe₂Pc/rGO. The N-CuMe₂Pc/rGO nanocomposite shows excellent photochemical recyclability which is essential for application in wastewater treatment.

The improved antibacterial efficiency of a zinc phthalocyanine when embedded on silver nanoparticle modified silica nanofibers

This work reports on the fabrication and modification of electrospun polymer free silica nanofibers (SiO₂ NFs) with the aim of creating heterogeneous antibacterial catalysts. The optical and photophysical properties of the obtained NFs i.e. bare SiO₂, Ag-SiO₂, Pc-SiO₂ and Pc@Ag-SiO₂ NFs (Pc = phthalocyanine) were compared and reported. The singlet oxygen quantum yields of the Pc-SiO₂ and Pc@Ag-SiO₂ NFs were also quantified and found to be 0.08 and 0.12, respectively, in water. All the modified SiO₂ NFs were found to possess photoactivity against S. aureus with the most effective being the Pc@Ag-SiO₂ NFs due to the synergy between the Pc and Ag nanoparticles. The bare SiO₂ NFs do not exhibit any antibacterial activity while the Ag-SiO₂ and Pc@Ag-SiO₂ NFs were found to also exhibit dark toxicity. The generated photocatalysts are attractive because they are active against bacteria and they are easily retrievable post-application. The nanocatalysts reported herein are therefore feasible candidates for real-life antibacterial applications.