Comparison of the possible histopathological changes of the rat neonatal cerebellum induced by toxic and nontoxic doses of biological silver nanoparticles with chemical silver nanoparticles

INTRODUCTION

Today, due to the increasing application of silver nanoparticles in medical products, it is necessary to pay attention to the user's safety. There are three methods, namely, chemical, physical, and biological, used for the production of nanoparticles. Although the first two methods might introduce health hazards, the latter is hypothetically safe. In this study, we examined the histopathological changes in the cerebellum of neonatal Wistar rats induced by injection of toxic and nontoxic doses of silver nanoparticles, which were produced by green synthetic method and were compared with chemical silver nanoparticles.

METHODS

This study was a laboratory interventional study performed on 25 Wistar rats in the Animal Laboratory of Islamic Azad University of Shahrood. These rats were divided into five groups of the control group, the group with nonpoisonous injection of chemical nanoparticles, the group with nonpoisonous injection of biological nanoparticles, the group with injection of poisonous chemical nanoparticles, and the group with injection of poisonous biological nanoparticles. The rats were impregnated by the males of the same race and the cerebellum of their offspring was studied after birth.

RESULTS

We found that the injection of nonpoisonous chemical nanoparticles caused hyperemia, inappropriate size, and dark cytoplasm in some Purkinje cells. Also, injection of poisonous chemical nanoparticles caused hyperemia and cellular dispersion in the molecular layer, caused abnormal shapes, and reduced the number of cells in Purkinje cells. However, injection of poisonous and nonpoisonous biological nanoparticles did not alter cerebellum cells nor did it cause any inflammation or hyperemia.

CONCLUSION

In contrast with chemical nanoparticles, biological nanoparticles have less significant effect on the cerebellum cells.

Silver distribution in chronic wounds and the healing dynamics of chronic wounds treated with dressings containing silver and octenidine

Although silver is an efficient antimicrobial and is a widely used antiseptic in wound healing, previous studies have reported the cytotoxic in vitro effects of silver dressings. Moreover, few studies have addressed the distribution of silver in chronic wounds. The study compares the healing of chronic wounds treated with a standard-of-care silver dressing (Ag-CMC) and a dressing containing antiseptic octenidine (OCT-HA). Biopsies were taken from two wound areas before the commencement of treatment (baseline), after 2 weeks and after 6 weeks (the end of the study). We analyzed the histopathologic wound-healing score, silver distribution, and expression of selected genes. The wound-healing score improved significantly in the wounded area treated with OCT-HA after 2 weeks compared to the baseline and the Ag-CMC. The Ag-CMC wound areas improved after 6 weeks compared to the baseline. Moreover, collagen maturation and decreases in the granulocyte and macrophage counts were faster in the OCT-HA parts. Treatment with OCT-HA resulted in less wound slough. The silver, visualized via autometallography, penetrated approximately 2 mm into the wound tissue and associated around capillaries and ECM fibers, and was detected in phagocytes. The metallothionein gene expression was elevated in the Ag-CMC wound parts. This exploratory study determined the penetration of silver into human chronic wounds and changes in the distribution thereof during treatment. We observed that silver directly affects the cells in the wound and elevates the metallothionein gene expression. Octenidine and hyaluronan dressings provide a suitable alternative to silver and carboxymethyl cellulose dressings without supplying silver to the wound.

Nanoparticles in the Treatment of Infections Caused by Multidrug-Resistant Organisms

Nanotechnology using nanoscale materials is increasingly being utilized for clinical applications, especially as a new paradigm for infectious diseases. Infections caused by multidrug-resistant organisms (MDROs) are emerging as causes of morbidity and mortality worldwide. Antibiotic options for infections caused by MDROs are often limited. These clinical challenges highlight the critical demand for alternative and effective antimicrobial strategies. Nanoparticles (NPs) can penetrate the cell membrane of pathogenic microorganisms and interfere with important molecular pathways, formulating unique antimicrobial mechanisms. In combination with optimal antibiotics, NPs have demonstrated synergy and may aid in limiting the global crisis of emerging bacterial resistance. In this review, we summarized current research on the broad classification of the NPs that have shown in vitro antimicrobial activity against MDROs, including the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). The pharmacokinetics and pharmacodynamic characteristics of NPs and bacteria-resistant mechanisms to NPs were also discussed.

Effectiveness of collagen/oxidised regenerated cellulose/silver-containing composite wound dressing for the treatment of medium-depth split-thickness skin graft donor site wounds in multi-morbid patients: a prospective, non-comparative, single-centre study

Split-thickness skin grafting (STSG) is a widely used method in reconstructive surgery, but donor site wounds (DSWs) are often slow healing and painful. This prospective study evaluated the performance of a composite wound dressing containing collagen/oxidised regenerated cellulose in the treatment of medium-depth (0·4 mm) DSWs in 25 multi-morbid patients with chronic leg ulcers requiring STSG. The range of patients' ages was 44-84 years (mean 71·6 years) with DSW sizes ranging between 12 and 162 cm2 (mean 78 cm2 ). Comorbidities included anticoagulation therapy (15 patients), anaemia (11 patients), diabetes (6 patients) and methicillin-resistant Staphylococcus aureus (MRSA) ulcer colonisation (6 patients). The first dressing change was performed after 10 days. Complete reepithelialisation was observed between the 10th and 34th day (mean 17·2, median 14 days). Postoperative medium to strong bleeding occurred in only five patients (four with anticoagulation). Wound pain levels one day after harvesting were only moderate (range 0-1·5, mean 0·5, median 0·5 on a six-item scale). No wound infection was observed during the first dressing. The composite dressing used allowed for the fast healing of medium-depth DSWs with minimal or no postoperative pain and bleeding in older multi-morbid patients under anticoagulation treatment.

A study on the in vitro percutaneous absorption of silver nanoparticles in combination with aluminum chloride, methyl paraben or di-n-butyl phthalate

Some reports indicate that the silver released from dermally applied products containing silver nanoparticles (AgNP) (e.g. wound dressings or cosmetics) can penetrate the skin, particularly if damaged. AgNP were also shown to have cytotoxic and genotoxic activity. In the present study percutaneous absorption of AgNP of two different nominal sizes (Ag15nm or Ag45nm by STEM) and surface modification, i.e. citrate or PEG stabilized nanoparticles, in combination with cosmetic ingredients, i.e. aluminum chloride (AlCl₃), methyl paraben (MPB), or di-n-butyl phthalate (DBPH) was assessed using in vitro model based on dermatomed pig skin. The inductively coupled plasma mass spectrometry (ICP-MS) measurements after 24h in receptor fluid indicated low, but detectable silver absorption and no statistically significant differences in the penetration between the 4 types of AgNP studied at 47, 470 or 750μg/ml. Similarly, no significant differences were observed for silver penetration when the AgNP were used in combinations with AlCl₃ (500μM), MPB (1250μM) or DBPH (35μM). The measured highest amount of Ag that penetrated was 0.45ng/cm² (0.365-0.974ng/cm²) for PEG stabilized Ag15nm+MPB.

A Review of Injectable and Implantable Biomaterials for Treatment and Repair of Soft Tissues in Wound Healing

The two major topics concerning the development of nanomedicine are drug delivery and tissue engineering. With the advance in nanotechnology, scientists and engineers now have the ability to fabricate functional drug carriers and/or biomaterials that deliver and release drugs locally as well as promote tissue regeneration. In this short review, we address the use of nanotechnology in the fabrication of biomaterials (i.e., nanoparticles and nanofibers) and their therapeutic function in wound healing as dressing materials. Furthermore, we discuss the use of surface nanofeatures to regulate cell adhesion, migration, proliferation, and differentiation, which is a crucial step in wound healing associated with tissue regeneration. Given that nanotechnology-based biomaterials exhibit superior pharmaceutical performance as compared to the traditional medicine, this short review provides current status and future directions of how nanotechnology is and will be used in biomedical field, especially in wound healing.

Current applications of nanoparticles in infectious diseases

For decades infections have been treated easily with drugs. However, in the 21st century, they may become lethal again owing to the development of antimicrobial resistance. Pathogens can become resistant by means of different mechanisms, such as increasing the time they spend in the intracellular environment, where drugs are unable to reach therapeutic levels. Moreover, drugs are also subject to certain problems that decrease their efficacy. This requires the use of high doses, and frequent administrations must be implemented, causing adverse side effects or toxicity. The use of nanoparticle systems can help to overcome such problems and increase drug efficacy. Accordingly, there is considerable current interest in their use as antimicrobial agents against different pathogens like bacteria, virus, fungi or parasites, multidrug-resistant strains and biofilms; as targeting vectors towards specific tissues; as vaccines and as theranostic systems. This review begins with an overview of the different types and characteristics of nanoparticles used to deliver drugs to the target, followed by a review of current research and clinical trials addressing the use of nanoparticles within the field of infectious diseases.