Michael K. Danquah’s research while affiliated with University of Tennessee at Knoxville and other places

BACKGROUND Staphylococcus aureus presents a major public health and food safety challenge due to its ability to thrive in various environments. Conventional methods, such as polymerase chain reaction and enzyme‐linked immunosorbent assay, often suffer from limitations in sensitivity and specificity, highlighting the need for innovative detection strategies. RESULTS This study developed novel label‐free aptasensors for S. aureus detection using copper nanoparticles (CuNPs) as a platform. The CuNPs, characterized by a size of 40 nm, spherical morphology, and functional stability, served as the foundation for the biosensor. An iron‐regulated surface determinant protein A (IsdA)‐binding aptamer, specifically targeting the IsdA surface protein of S. aureus, was conjugated to CuNPs as the molecular recognition probe, while rhodamine 6G acted as the signal probe. In the absence of S. aureus, the aptamer kept the ‘gate’ on the CuNPs closed, preventing signal probe release. In the presence of S. aureus, specific binding between the aptamer and the pathogen triggered the ‘gate’ to open, releasing rhodamine 6G and generating a fluorescence signal. The aptasensors demonstrated a linear detection range of (10–10⁶) CFU mL⁻¹, with a detection limit of 1 CFU mL⁻¹ (correlation coefficient R² = 0.947). The biosensor demonstrated high stability and reproducibility, ensuring consistent detection performance. Furthermore, its application for S. aureus detection in milk samples highlighted its practical utility. CONCLUSION These findings establish the CuNP‐based aptasensor as a promising tool for sensitive and reliable S. aureus detection, with potential applications in food safety monitoring and public health. © 2025 Society of Chemical Industry (SCI).

Rapid and reliable detection of pathogens requires precise and optimized analytical techniques to address challenges in food safety and public health. This study focuses on the parametric characterization of an electrochemical aptasensor for Staphylococcus aureus (S. aureus) iron-regulated surface determinant protein A (IsdA) using cyclic voltammetry (CV) analysis, which offers a robust method for evaluating electrode modifications and electrochemical responses. Key parameters were optimized to ensure maximum sensitivity, including an aptamer concentration of 5 μM, an incubation time of 4 h, a potential range from −0.1 to 0.9 V, and a scan rate of 0.05 V/s. The aptasensor achieved stability and peak performance at pH 7.5 and 25 °C. These conditions were critical for detecting the IsdA protein as a biomarker of S. aureus. The aptasensor applicability was demonstrated by successfully detecting S. aureus in food samples such as milk and apple juice with high specificity and reliability. Zeta potential measurements confirmed the layer-by-layer charge dynamics of the AuNPs-aptamer-IsdA system. This work emphasizes the importance of CV in understanding the performance of the electrochemical sensor, and supports the aptasensor as a practical, sensitive, and portable tool for addressing critical gaps in foodborne pathogen detection.

Agricultural waste has emerged as a pressing concern for numerous countries worldwide. While these wastes may be less toxic compared to other forms of waste, their volume poses a significant challenge. They can encroach upon valuable agricultural lands, encumber forests, and even infiltrate residential areas due to their extensive production. Moreover, efforts to recycle these agricultural wastes have, in some cases, resulted in the creation of additional hazardous byproducts. Thus, there arises a compelling need for innovative approaches to harness these agricultural residues for potential material fabrication, particularly with a focus on their applicability in biomedical contexts. In recent times, agricultural waste materials have gained considerable attention among researchers as a valuable resource for the synthesis of carbon-based nanomaterials. Their richness in carbon content, coupled with the need for recycling, presents distinct advantages over conventional methods of carbon-based nanomaterial synthesis, which can have pronounced environmental impacts. This chapter offers a comprehensive overview of various agricultural waste sources and their potential utility in the synthesis of carbon nanomaterials. The discussion extends to exploring the diverse applications of these biosynthesized carbon nanomaterials within the field of biomedicine. Repurposing agricultural waste into advanced nanomaterials with biomedical significance can potentially address both environmental concerns and the growing demand for innovative materials in the healthcare sector. This integration of sustainability and cutting-edge science underscores the transformative potential of agricultural waste in shaping a more sustainable and technology-driven future for various applications, particularly in the biomedicine space.

Short amino acid chains known as peptides are widely used in pharmaceutical applications due to their exclusive therapeutic potential and distinct biological activities. These peptides are utilized as therapeutic agents for the treatment of various medical conditions and diseases, peptide hormones for hormone deficiency treatment, peptide vaccines to be utilized as antigens to induce specific immune responses against cancer cells or pathogens, and peptide-based drug delivery systems. However, poor stability, limited oral bioavailability, high immunogenicity leading to reduced efficacy, high cost of production, low target specificity, challenges in formulation and tissue penetration. Recently, nanomaterials, especially nanocomposites, have been utilized for the formulation of therapeutic peptides to improve their efficiency and overcome their limitations. In particular, biocomposite nanomaterials from natural sources are also reported to effectively formulate and deliver therapeutic peptides toward target site. Thus, this chapter is an overview of various biocomposite nanomaterials for the formulation of peptides to improve their efficiency. Additionally, pharmaceutical applications of these biocomposite nanomaterial formulated peptides were also discussed.

Conventional energy storage systems, such as pumped hydroelectric storage, lead–acid batteries, and compressed air energy storage (CAES), have been widely used for energy storage. However, these systems face significant limitations, including geographic constraints, high construction costs, low energy efficiency, and environmental challenges. Among these, lead–acid batteries, despite their widespread use, suffer from issues such as heavy weight, sensitivity to temperature fluctuations, low energy density, and limited depth of discharge. Lithium-ion batteries (LIBs) have emerged as a promising alternative, offering portability, fast charging, long cycle life, and higher energy density. However, LIBs still face challenges related to limited lifespan, safety concerns (such as overheating), and environmental impact due to resource extraction and emissions. This review explores the introduction of nanotechnology as a transformative approach to enhance efficiency and overcome the limitations of LIBs. We provide an in-depth overview of various nanotechnology-based solutions for LIBs, focusing on their impact on energy density, cycle life, safety, and environmental sustainability. Additionally, we discuss advanced thermal analysis techniques used to assess and improve the performance of nanotechnology-enhanced LIBs. Finally, we examine the role of nanoparticles in the environmental remediation of LIBs, offering insights into how they can mitigate the ecological footprint of battery disposal and recycling. This review aims to highlight the potential of nanotechnology to revolutionize energy storage systems and address the growing demand for efficient and sustainable energy solutions.

Staphylococcus aureus (S. aureus), a common foodborne pathogen, poses significant public health challenges due to its association with various infectious diseases. A key player in its pathogenicity, which is the IsdA protein, is an essential virulence factor in S. aureus infections. In this work, we present an integrated in-silico and experimental approach using MD simulations and surface plasmon resonance (SPR)-based aptasen-sing measurements to investigate S. aureus biorecognition via IsdA surface protein binding. SPR, a powerful real-time and label-free technique, was utilized to characterize interaction dynamics between the aptamer and IsdA protein, and MD simulations was used to characterize the stable and dynamic binding regions. By characterizing and optimizing pivotal parameters such as aptamer concentration and buffer conditions, we determined the aptamer's binding performance. Under optimal conditions of pH 7.4 and 150 mM NaCl concentration, the kinetic parameters were determined; k a = 3.789 Â 10 4 /Ms, k d = 1.798 Â 10 3 /s, and K D = 4.745 Â 10 À8 M. The simulations revealed regions of interest in the IsdA-aptamer complex. Region I, which includes interactions between amino acid residues H106 and R107 and nucleotide residues 9G, 10U, 11G and 12U of the aptamer, had the strongest interaction, based on ΔG and B-factor values, and hence contributed the most to the stability of the interaction. Region II, which covers residue 37A reflects the dynamic nature of the interaction due to frequent contacts. The approach presents a rigorous characterization of aptamer-IsdA binding behavior, supporting the potential application of the IsdA-binding aptamer system for S. aureus biosensing. K E Y W O R D S aptamer, aptasensor, Bioaffinity, IsdA protein, MD simulations, S. aureus, surface plasmon resonance

Staphylococcus aureus (S. aureus) is recognized as one of the most common causes of gastroenteritis worldwide. This pathogen is a major foodborne pathogen that can cause many different types of various infections, from minor skin infections to lethal blood infectious diseases. Iron-regulated surface determinant protein A (IsdA) is an important protein on the S. aureus surface. It is responsible for iron scavenging via interaction with hemoglobin, haptoglobin, and hemoglobin-haptoglobin complexes. This study develops a portable aptasensor for IsdA and S. aureus detection using aptamer-modified gold nano-particles (AuNPs) integrated into screen-printed carbon electrodes (SPCEs). The electrode system was made of three parts, including a carbon counter electrode, an AuNPs/carbon working electrode, and a silver reference electrode. The aptamer by Au-S bonding was conjugated on the electrode surface to create the aptasensor platform. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were utilized to investigate the binding interactions between the aptasensor and the IsdA protein. CV studies showed a linear correlation between varying S. aureus concentrations within the range of 10 1 to 10 6 CFU/mL, resulting in a limit of detection (LOD) of 0.2 CFU/mL. The results demonstrated strong reproducibility, selectivity, and sensitivity of the aptasensor for enhanced detection of IsdA, along with about 93% performance stability after 30 days. The capability of the aptasensor to directly detect S. aureus via the IsdA surface protein binding was further investigated in a food matrix. Overall, the aptasensor device showed the potential for rapid detection of S. aureus, serving as a robust approach to developing real-time aptasensors to identify an extensive range of targets of foodborne pathogens and beyond.