Delivery of antibacterial silver nanoclusters to Pseudomonas aeruginosa using species-specific DNA aptamers

Advances in skin gene therapy: utilizing innovative dressing scaffolds for wound healing, a comprehensive review

The skin, serving as the body's outermost layer, boasts a vast area and intricate structure, functioning as the primary barrier against external threats. Disruptions in the composition and functionality of the skin can lead to a diverse array of skin conditions, such as wounds, burns, and diabetic ulcers, along with inflammatory disorders, infections, and various types of skin cancer. These disorders not only exacerbate concerns regarding skin health and beauty but also have a significant impact on mental well-being. Due to the complexity of these disorders, conventional treatments often prove insufficient, necessitating the exploration of new therapeutic approaches. Researchers develop new therapies by deciphering these intricacies and gaining a thorough understanding of the protein networks and molecular processes in skin. A new window of opportunity has opened up for improving wound healing processes because of recent advancements in skin gene therapy. To enhance skin regeneration and healing, this extensive review investigates the use of novel dressing scaffolds in conjunction with gene therapy approaches. Scaffolds that do double duty as wound protectors and vectors for therapeutic gene delivery are being developed using innovative biomaterials. To improve cellular responses and speed healing, these state-of-the-art scaffolds allow for the targeted delivery and sustained release of genetic material. The most recent developments in gene therapy techniques include RNA interference, CRISPR-based gene editing, and the utilization of viral and non-viral vectors in conjunction with scaffolds, which were reviewed here to overcome skin disorders and wound complications. In the future, there will be rare chances to develop custom methods for skin health care thanks to the combination of modern technology and collaboration among disciplines.

Expert opinion on antimicrobial therapies: is there enough scientific evidence to state that targeted therapies outperform non-targeted ones?

INTRODUCTION

Different active and passive strategies have been developed to fight against pathogenic bacteria. Those actions are undertaken to reduce the bacterial burden while minimizing the possibilities to develop not only antimicrobial resistance but also antimicrobial side-effects such as allergic or hypersensitivity reactions.

AREAS COVERED

We have reviewed preclinical results that evidence that targeted antimicrobial therapies outperform non-targeted ones. Active selective targeting against pathogenic bacteria has been achieved through the functionalization of antimicrobials, either alone or encapsulated within micro- or nanocarriers, with various recognition moieties. These moieties include peptides, aptamers, antibodies, carbohydrates, extracellular vesicles, cell membranes, infective agents, and other affinity ligands with specific bacterial tropism. Those selective ligands increase retention and enhance effectiveness reducing the side-effects and the required dose to exert the antimicrobial action at the site of infection.

EXPERT OPINION

When using targeted antimicrobial therapies not only reduced side-effects are observed, but also, compared to the administration of equivalent doses of the non-targeted drugs, a superior efficacy has been demonstrated against planktonic, sessile, and intracellular pathogenic bacterial persisters. The translation of those targeted therapies to subsequent phases of clinical development still requires the demonstration of a reduction in the probabilities for the pathogen to develop resistance when using targeted approaches.

Diagnosis and Therapeutic Strategies Based on Nucleic Acid Aptamers Selected against Pseudomonas aeruginosa: The Challenge of Cystic Fibrosis

Antimicrobial resistance (AMR) is a rapidly spreading global health problem, and approximately five million deaths associated with AMR pathogens were identified prior to the COVID-19 pandemic. Pseudomonas aeruginosa has developed increasing AMR, and in patients with cystic fibrosis (CF) colonized by this bacterium, rare phenotypes have emerged that complicate the diagnosis and treatment of the hosts, in addition to multiple associated "epidemic strains" with high morbidities and mortalities. The conjugation of aptamers with fluorochromes or nanostructures has allowed the design of new identification strategies for Pseudomonas aeruginosa with detection limits of up to 1 cell ⋅ mL-1 , and the synergy of aptamers with antibiotics, antimicrobial peptides and nanostructures has exhibited promising therapeutic qualities. Some selected aptamers against this bacterium have shown intrinsic antimicrobial activity. However, these aptamers have been poorly evaluated in clinical isolates and have shown decreased interactions for CF isolates, demonstrating, in these cases, uncommon phenotypes resulting from the selective qualities of this disease as well as the great adaptive capacity of the pathogen. Therefore, finding an aptamer or set of aptamers that have the ability to recognize strange phenotypes of this bacillus is crucial in the battle against AMR.

Applications and Challenges of Bacteriostatic Aptamers in the Treatment of Common Pathogenic Bacteria Infections

The continuous evolution and spread of common pathogenic bacteria is a major challenge in diagnosis and treatment with current biotechnology and modern molecular medicine. To confront this challenge, scientists urgently need to find alternatives for traditional antimicrobial agents. Various bacteriostatic aptamers obtained through SELEX screening are one of the most promising strategies. These bacteriostatic aptamers can reduce bacterial infection by blocking bacterial toxin infiltration, inhibiting biofilm formation, preventing bacterial invasion of immune cells, interfering with essential biochemical processes, and other mechanisms. In addition, aptamers may also help enhance the function of other antibacterial materials/drugs when used in combination. This paper has reviewed the bacteriostatic aptamers in the treatment of common pathogenic bacteria infections. For this aspect, first, bacteriostatic aptamers and their screening strategies are summarized. Then, the effect of molecular tailoring and modification on the performance of the bacteriostatic aptamer is analyzed, and the antibacterial mechanism and antibacterial strategy based on aptamers are introduced. Finally, the key technical challenges and their development prospects in clinical treatment are also carefully discussed.

Optical, structural and antibacterial properties of silver nanoparticles and DNA-templated silver nanoclusters

Silver nanoparticles (AgNPs) are increasingly considered for biomedical applications as drug-delivery carriers, imaging probes and antibacterial agents. Silver nanoclusters (AgNCs) represent another subclass of nanoscale silver. AgNCs are a promising tool for nanomedicine due to their small size, structural homogeneity, antibacterial activity and fluorescence, which arises from their molecule-like electron configurations. The template-assisted synthesis of AgNCs relies on organic molecules that act as polydentate ligands. In particular, single-stranded nucleic acids reproducibly scaffold AgNCs to provide fluorescent, biocompatible materials that are incorporable in other formulations. This mini review outlines the design and characterization of AgNPs and DNA-templated AgNCs, discusses factors that affect their physicochemical and biological properties, and highlights applications of these materials as antibacterial agents and biosensors.

Current approaches for the exploration of antimicrobial activities of nanoparticles

Infectious diseases of bacterial and viral origins contribute to substantial mortality worldwide. Collaborative efforts have been underway between academia and the industry to develop technologies for a more effective treatment for such diseases. Due to their utility in various industrial applications, nanoparticles (NPs) offer promising potential as antimicrobial agents against bacterial and viral infections. NPs have been established to possess potent antimicrobial activities against various types of pathogens due to their unique characteristics and cell-damaging ability through several mechanisms. The recently accepted antimicrobial mechanisms possessed by NPs include metal ion release, oxidative stress induction, and non-oxidative mechanisms. Another merit of NPs lies in the low likelihood of the development of microbial tolerance towards NPs, given the multiple simultaneous mechanisms of action against the pathogens targeting numerous gene mutations in these pathogens. Moreover, NPs provide a fascinating opportunity to curb microbial growth before infections: this outstanding feature has led to their utilization as active antimicrobial agents in different industrial applications, e.g. the coating of medical devices, incorporation in food packaging, promoting wound healing and encapsulation with other potential materials for wastewater treatment. This review discusses the progress and achievements in the antimicrobial applications of NPs, factors contributing to their actions, mechanisms underlying their efficiency, and risks of their applications, including the antimicrobial action of metal nanoclusters (NCs). The review concludes with a discussion of the restrictions on present studies and future prospects of nanotechnology-based NPs development.

Oligonucleotide aptamers for pathogen detection and infectious disease control

During an epidemic or pandemic, the primary task is to rapidly develop precise diagnostic approaches and effective therapeutics. Oligonucleotide aptamer-based pathogen detection assays and control therapeutics are promising, as aptamers that specifically recognize and block pathogens can be quickly developed and produced through simple chemical synthesis. This work reviews common aptamer-based diagnostic techniques for communicable diseases and summarizes currently available aptamers that target various pathogens, including the SARS-CoV-2 virus. Moreover, this review discusses how oligonucleotide aptamers might be leveraged to control pathogen propagation and improve host immune system responses. This review offers a comprehensive data source to the further develop aptamer-based diagnostics and therapeutics specific for infectious diseases.

Highly efficient nanomedicine from cationic antimicrobial peptide-protected Ag nanoclusters

Designing the homogeneous assembly of the bio-nano interface to fine-tune the interactions between the nanoprobes and biological systems is of prime importance to improve the antimicrobial efficiency of nanomedicines. In this work, highly luminescent silver nanoclusters with the homogeneous conjugation of an antimicrobial peptide (referred to as Dpep-Ag NCs) were achieved via the reduction-decomposition-reduction process as a single package. The as-designed Dpep-Ag NCs inherited the two distinctive features of bactericides from the Ag+ species and the antimicrobial peptide of Dpep, and exhibited enhanced bacterial killing efficiency compared with other control groups including BSA-capped Ag NCs and the original antimicrobial peptide bactenecin (Opep)-protected Ag nanoparticles (Opep-Ag NPs). The ultrasmall size feature of Dpep-Ag NCs combined with the positively charged bactericidal tail allow a better interface and interaction with the cell membrane owing to the selective targeting of lipopolysaccharides in the Gram-negative bacteria and electrostatic interaction, facilitating the membrane permeability. Dpep-Ag NCs restrained the E. coli growth visibly and outperformed commercial Ag NPs (30 nm) with reduced (ca. 100-fold) minimal inhibitory concentration. The analysis of infected wound sizes and tissues treated with Dpep-Ag NCs in a murine model reveal obvious differences in the healing effect compared with the other counterparts, demonstrating its antibacterial efficiency in practical application.

The greater wax moth Galleria mellonella: biology and use in immune studies

The greater wax moth Galleria mellonella is an invertebrate that is increasingly being used in scientific research. Its ease of reproduction, numerous offspring, short development cycle, and finally, its known genome and immune-related transcriptome provide a convenient research model for investigation of insect immunity at biochemical and molecular levels. Galleria immunity, consisting of only innate mechanisms, shows adaptive plasticity, which has recently become the subject of intensive scientific research. This insect serves as a mini host in studies of the pathogenicity of microorganisms and in vivo tests of the effectiveness of single virulence factors as well as new antimicrobial compounds. Certainly, the Galleria mellonella species deserves our attention and appreciation for its contribution to the development of research on innate immune mechanisms. In this review article, we describe the biology of the greater wax moth, summarise the main advantages of using it as a model organism and present some of the main techniques facilitating work with this insect.

Spectroscopic Study on Pseudomonas Aeruginosa Biofilm in the Presence of the Aptamer-DNA Scaffolded Silver Nanoclusters

We report the effectiveness of silver nanocluster (Ag-NC) against the biofilm of Pseudomonas aeruginosa (PA). Two DNA aptamers specific for PA and part of their sequences were chosen as templates for growing the Ag-NC. While circular dichroism (CD) studies determined the presence of secondary structures, UV/Vis absorption, and fluorescence spectroscopic studies confirmed the formation of the fluorescent Ag-NC on the DNA templates. Furthermore, mesoscopic physics-based partial wave spectroscopy (PWS) was used to analyze the backscattered light signal that can detect the degree of nanoscale mass density/refractive index fluctuations to identify the biofilm formation, comparatively among the different aptamers with respect to the control sample. The importance of the secondary structure of the aptamer DNA in targeting, successfully binding with the cells and delivering the Ag-NC, is evidenced by the decrease in disorder strength (L_d) of the Ag-NC treated samples compared to the untreated PA cells, which showed the abundance of higher L_d in the PWS studies. The higher L_d value attributed to the higher mass density fluctuations and the formation of biofilm. We envision this study to open a new avenue in using a powerful optical microscopic technique like PWS in detection, and DNA aptamer enclosed silver nanoclusters to prevent biofilms for opportunist pathogens like Pseudomonas aeruginosa.