Biochemical assessment of the neurotoxicity of gold nanoparticles functionalized with colorectal cancer-targeting peptides in a rat model

Navigating Neurotoxicity and Safety Assessment of Nanocarriers for Brain Delivery: Strategies and Insights

Nanomedicine, an area that uses nanomaterials for theragnostic purposes, is advancing rapidly, particularly in the detection and treatment of neurodegenerative diseases. The design of nanocarriers can be optimized to enhance drug bioavailability and targeting to specific organs, improving therapeutic outcomes. However, clinical translation hinges on biocompatibility and safety. Nanocarriers can cross the blood-brain barrier (BBB), potentially causing neurotoxic effects through mechanisms such as oxidative stress, DNA damage, and neuroinflammation. Concerns about their accumulation and persistence in the brain make it imperative to carry out a nanotoxicological risk assessment. Generally, this involves identifying exposure sources and routes, characterizing physicochemical properties, and conducting cytotoxicity assays both in vitro and in vivo. The lack of a specialized regulatory framework creates substantial gaps, making it challenging to translate findings across development stages. Additionally, there is a pressing need for innovative testing methods due to constraints on animal use and the demand for high-throughput screening. This review examines the mechanisms of nanocarrier-induced neurotoxicity and the challenges in risk assessment, highlighting the impact of physicochemical properties and the advantages and limitations of current neurotoxicity evaluation models. Future perspectives are also discussed. Additional guidance is crucial to improve the safety of nanomaterials and reduce associated uncertainty. STATEMENT OF SIGNIFICANCE: Nanocarriers show tremendous potential for theragnostic purposes in neurological diseases, enhancing drug targeting to the brain, and improving biodistribution and pharmacokinetics. However, their neurotoxicity is still a major field to be explored, with only 5% of nanotechnology-related publications addressing this matter. This review focuses on the issue of neurotoxicity and safety assessment of nanocarriers for brain delivery. Neurotoxicity-relevant exposure sources, routes, and molecular mechanisms, along with the impact of the physicochemical properties of nanomaterials, are comprehensively described. Moreover, the different experimental models used for neurotoxicity evaluation are explored at length, including their main advantages and limitations. To conclude, we discuss current challenges and future perspectives for a better understanding of risk assessment of nanocarriers for neurobiomedical applications.

Nanomaterials in biology and medicine: a new perspective on its toxicity and applications

Nanotechnology offers excellent prospects for application in biology and medicine. It is used for detecting biological molecules, imaging, and as therapeutic agents. Due to nano-size (1-100 nm) and high surface-to-volume ratio, nanomaterials possess highly specific and distinct characteristics in the biological environment. Recently, the use of nanomaterials as sensors, theranostic, and drug delivery agents has become popular. The safety of these materials is being questioned because of their biological toxicity, such as inflammatory responses, cardiotoxicity, cytotoxicity, inhalation problems, etc., which can have a negative impact on the environment. This review paper focuses primarily on the toxicological effects of nanomaterials along with the mechanisms involved in cell interactions and the generation of reactive oxygen species by nanoparticles, which is the fundamental source of nanotoxicity. We also emphasize the greener synthesis of nanomaterials in biomedicine, as it is non-hazardous, feasible, and economical. The review articles shed light on the complexities of nanotoxicology in biosystems and the environment.

Tau- and α-synuclein-targeted gold nanoparticles: applications, opportunities, and future outlooks in the diagnosis and therapy of neurodegenerative diseases

The use of nanomaterials in medicine offers multiple opportunities to address neurodegenerative disorders such as Alzheimer's and Parkinson's disease. These diseases are a significant burden for society and the health system, affecting millions of people worldwide without sensitive and selective diagnostic methodologies or effective treatments to stop their progression. In this sense, the use of gold nanoparticles is a promising tool due to their unique properties at the nanometric level. They can be functionalized with specific molecules to selectively target pathological proteins such as Tau and α-synuclein for Alzheimer's and Parkinson's disease, respectively. Additionally, these proteins are used as diagnostic biomarkers, wherein gold nanoparticles play a key role in enhancing their signal, even at the low concentrations present in biological samples such as blood or cerebrospinal fluid, thus enabling an early and accurate diagnosis. On the other hand, gold nanoparticles act as drug delivery platforms, bringing therapeutic agents directly into the brain, improving treatment efficiency and precision, and reducing side effects in healthy tissues. However, despite the exciting potential of gold nanoparticles, it is crucial to address the challenges and issues associated with their use in the medical field before they can be widely applied in clinical settings. It is critical to ensure the safety and biocompatibility of these nanomaterials in the context of the central nervous system. Therefore, rigorous preclinical and clinical studies are needed to assess the efficacy and feasibility of these strategies in patients. Since there is scarce and sometimes contradictory literature about their use in this context, the main aim of this review is to discuss and analyze the current state-of-the-art of gold nanoparticles in relation to delivery, diagnosis, and therapy for Alzheimer's and Parkinson's disease, as well as recent research about their use in preclinical, clinical, and emerging research areas.

Synthesized gold nanoparticles mediated by Crassocephalum rubens extract down-regulate KIM-1/NGAL genes and inhibit oxidative stress in cadmium-induced kidney damage in rats

Cadmium (Cd) exposure induces kidney damage by mediating oxidative stress and inflammation. In this study, the role of Crassocephalum rubens-gold nanoparticles (C. rubens-AuNPs) in down-regulating kidney injury molecules-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) genes and inhibiting oxidative stress in Cd-induced kidney damage in rats was investigated. Thirty male Wistar rats were distributed randomly into six groups (n = 5). Group I served as control, while groups II, III, IV, and V rats were administered with 20 mg/kg b.w. cadmium chloride (CdCl2) for five consecutive days. Groups III, IV, and V rats were treated, 24 h after the last dose of CdCl2, with silymarin, 5 mg/kg and 10 mg/kg C. rubens-AuNPs, respectively, for 14 days. Group VI rats received 10 mg/kg C. rubens-AuNPs only for 14 days. Animals were sacrificed 24 h after the last dose of the treatment. Biochemical parameters such as kidney function markers, biomarkers of nephrotoxicity, and oxidative stress markers were assayed. Results indicated that 20 mg/kg b.w. CdCl2 caused kidney damage, as evidenced by significant (p < 0.05) increase in the levels of serum urea and creatinine, malondialdehyde, reduced level of superoxide dismutase (SOD), and increased mRNA expression of the kidney injury biomarkers (KIM-1 and NGAL genes), when compared with the control. However, these changes were attenuated by both doses of C. rubens-AuNPs when compared with Cd-induced nephrotoxic rats. It can be suggested that C. rubens-AuNPs have the potential to ameliorate kidney damage induced by Cd via oxidative stress inhibition and down-regulation of KIM-1/NGAL genes.