A highly sensitive electrochemical immunosensor based on coral-shaped AuNPs with CHITs inorganic–organic hybrid film

Copper and nanocopper toxicity using integrated biomarker response in Pangasianodon hypophthalmus

The current study focused on assessing the toxicological effects of copper (Cu) and copper nanoparticles (Cu-NPs) in acute condition on Pangasianodon hypophthalmus. The median lethal concentration (LC50 ) for Cu and Cu-NPs were determined as 8.04 and 3.85 mg L-1 , respectively. For the subsequent definitive test, varying concentrations were selected: 7.0, 7.5, 8.0, 8.5, and 9.0 mg L-1 for Cu, and 3.0, 3.3, 3.6, 3.9, and 4.2 mg L-1 for Cu-NPs. To encompass these concentration levels and assess their toxic effects, biomarkers associated with toxicological studies like oxidative stress, neurotransmission, and cellular metabolism were measured in the liver, kidney, and gill tissues. Notably, during the acute test, the activities of catalase, superoxide dismutase, glutathione-s-transferase, glutathione peroxidase, and lipid peroxide in the liver, gill, and kidney tissues were significantly increased due to exposure to Cu and Cu-NPs. Similarly, acetylcholinesterase activity in the brain was notably inhibited in the presence of Cu and Cu-NPs when compared to the control group. Cellular metabolic stress was greatly influenced by the exposure to Cu and Cu-NPs, evident from the considerable elevation of cortisol, HSP 70, and blood glucose levels in the treated groups. Furthermore, integrated biomarker response, genotoxicity, DNA damage in gill tissue, karyotyping in kidney tissue, and histopathology in gill and liver were investigated, revealing tissue damage attributed to exposure to Cu and Cu-NPs. In conclusion, this study determined that elevated concentrations of essential trace elements, namely Cu and Cu-NPs, induce toxicity and disrupt cellular metabolic activities in fish.

Biosensors for Detection of Human Placental Pathologies: A Review of Emerging Technologies and Current Trends

Substantial growth in the biosensor research has enabled novel, sensitive and point-of-care diagnosis of human diseases in the last decade. This paper presents an overview of the research in the field of biosensors that can potentially predict and diagnosis of common placental pathologies. A survey of biomarkers in maternal circulation and their characterization methods is presented, including markers of oxidative stress, angiogenic factors, placental debris, and inflammatory biomarkers that are associated with various pathophysiological processes in the context of pregnancy complications. Novel biosensors enabled by microfluidics technology and nanomaterials is then reviewed. Representative designs of plasmonic and electrochemical biosensors for highly sensitive and multiplexed detection of biomarkers, as well as on-chip sample preparation and sensing for automatic biomarker detection are illustrated. New trends in organ-on-a-chip based placental disease models are highlighted to illustrate the capability of these in vitro disease models in better understanding the complex pathophysiological processes, including mass transfer across the placental barrier, oxidative stress, inflammation, and malaria infection. Biosensor technologies that can be potentially embedded in the placental models for real time, label-free monitoring of these processes and events are suggested. Merger of cell culture in microfluidics and biosensing can provide significant potential for new developments in advanced placental models, and tools for diagnosis, drug screening and efficacy testing.

An Ultrasensitive Electrochemical Immunosensor for Alpha-Fetoprotein Using an Envision Complex-Antibody Copolymer as a Sensitive Label

A novel strategy is presented for sensitive detection of alfa-fetoprotein (AFP), using a horseradish peroxidase (HRP)-functionalized Envision antibody complex (EVC) as the label. The Envision-AFP signal antibody copolymer (EVC-AFP Ab2) was composed of a dextran amine skeleton anchoring more than 100 molecules of HRP and 15 molecules of secondary antibody, and acted as a signal tag in the immunosensor. The sensor was constructed using the following steps: First, gold electrode (GE) was modified with nano-gold (AuNPs) by electro-deposition in HAuCl₄ solution. The high affinity of the AuNPs surface facilitates direct formation of a self-assembled thiolated protein G layer. Next, the coated GE was incubated in a solution of AFP capture antibody (AFP Ab1); these antibodies attach to the thiolated protein G layer through their non-antigenic regions, leaving the antigen binding sites for binding of target analyte. Following a sandwich immunoreaction, an EVC-AFP Ab2-AFP-AFP Ab1 immunocomplex was formed on the electrode surface, allowing large amounts of HRP on the complex to produce an amplified electrocatalytic current of hydroquinone (HQ) in the presence of hydrogen peroxide (H₂O₂). Highly amplified detection was achieved, with a detection limit of 2 pg/mL and a linear range of 0.005–0.2 ng/mL for AFP in 10 μL undiluted serum; this is near or below the normal levels of most cancer biomarker proteins in human serum. Measurements of AFP in the serum of cancer patients correlated strongly with standard enzyme-linked immunosorbent assays. These easily fabricated EVC-modified immunosensors show excellent promise for future fabrication of bioelectronic arrays. By varying the target biomolecules, this technique may be easily extended for use with other immunoassays, and thus represents a versatile design route.