In this work we investigated the antibacterial properties of differently shaped silver nanoparticles against the gram-negative bacterium Escherichia coli , both in liquid systems and on agar plates. Energy-filtering transmission electron microscopy images revealed considerable changes in the cell membranes upon treatment, resulting in cell death. Truncated triangular silver nanoplates with a {111} lattice plane as the basal plane displayed the strongest biocidal action, compared with spherical and rod-shaped nanoparticles and with Ag ⁺ (in the form of AgNO ₃ ). It is proposed that nanoscale size and the presence of a {111} plane combine to promote this biocidal property. To our knowledge, this is the first comparative study on the bactericidal properties of silver nanoparticles of different shapes, and our results demonstrate that silver nanoparticles undergo a shape-dependent interaction with the gram-negative organism E. coli .

Advancements in nano-structured materials have facilitated several applications of nanoparticles (NPs). Skin penetration of NPs is a crucial factor for designing suitable topical antibacterial agents with low systemic toxicity. Available reports focus on size-dependent skin penetration of NPs, mainly through follicular pathways. Herein, for the first time, we demonstrate a proof-of-concept study that entails variations in skin permeability and diffusion coefficients, penetration rates and depth-of-penetration of differently shaped silver NPs (AgNPs) via intercellular pathways using both in vitro and in vivo models. The antimicrobial activity of AgNPs is known. Different shapes of AgNPs may exhibit diverse antimicrobial activities and skin penetration capabilities depending upon their active metallic facets. Consideration of the shape dependency of AgNPs in antimicrobial formulations could help developing an ideal topical agent with the highest efficacy and low systemic toxicity.

Even with the prevalence of wounds, the medical technology for efficiently managing skin damage is still primitive. The disruption of any of the numerous healing processes can lead to problems in the time-sensitive healing actions of the dermal and epidermal layers. Bacterial infection is one of the major obstacles to proper wound healing as it poses a danger of causing long-term negative effects. Keeping the wound free of bacteria is imperative to the proper and hasty repair of dermal wounds. Silver has been widely used to treat wounds for its bactericidal properties. Although the mechanism of silver's antibacterial action is not fully understood, it exhibits a significant antimicrobial efficacy against a wide spectrum of bacterial species. A number of different approaches to the mechanism are reported and presented in this review. Silver nanoparticles (AgNPs) have been reported to exhibit enhanced antibacterial activity due to their increased surface-area-to-volume ratio. AgNPs are capable of various modifications, significantly broadening the therapeutic properties of the material as a result. This review explores the different aspects of silver and silver nanoparticles, and their antibacterial properties, which can be applied in the field of wound treatments.

The combination of chemotherapy and photodynamic therapy (chemo–PDT) has been suggested as an alternative therapy for drug-resistant cancers. In this study, biotin-conjugated PEGylated photosensitizer (PS) self-assembled nanoparticles (meso-tetraphenylporphyrin (TPP)–PEG–biotin SANs) were prepared via a self-assembly process to serve as nanocarriers for chemo-drugs as well as PSs. Electron microscopy results reveal the spherical shape of the nanoparticles (NPs). In the NPs, conjugated biotin plays a key role in selective tumor targeting. In vitro cellular experiments revealed the rapid cellular uptake of the TPP–PEG–biotin conjugates by MCF-7 cells that overexpress the biotin receptor, and verified that the conjugates were much more effective PSs than TPPS used as control in the cytotoxicity test. Interestingly, subcellular localization studies showed that the conjugates and their self-assembled NPs were localized mainly in mitochondria and partially in lysosomes, whereas TPPS was localized only in lysosomes. With the exclusive localization in mitochondria, high-content cell based assay showed that the TPP–PEG–biotin SANs induced rapid mitochondrial membrane potential transition (MPT), leading to cellular apoptosis. The chemo-drug doxorubicin (DOX) was successfully encapsulated in the TPP–PEG–biotin SANs (DOX@TPP–PEG–biotin) and had synergistic effects with enhanced cytotoxicity after PDT action. Collectively, the DOX@TPP–PEG–biotin SANs have promising potential as an effective anticancer agent in targeted combination therapy.