Biosensors Conference

Abstract

The detection of foodborne pathogens, such as Salmonella, requires the development of methods capable of on-site measurement due to the complexities associated with traditional approaches. In this regard, we present a superhydrophobic magneto-flow system integrated with an electrochemical aptasensor, designed for the straightforward, sensitive, and controllable detection of Salmonella in food samples, which is recognized as a significant foodborne pathogen. The overall process, encompassing the capturing of Salmonella by aptamers, washing procedures, and electrochemical measurements, was conducted on a single superhydrophobic device with a custom-designed pattern resembling a move-pause station, facilitating the use of only a single spotting of samples and reagents. A laminate magneto-driven microfluidic device was produced through laser cutting and assembly to create channel barriers, allowing for precise control of magnetic flow direction via magnetic force, thus eliminating the need for external pumps or adsorbent pads. Aptamers specific to Salmonella were conjugated to magnetic bead nanoparticles and subsequently oriented onto a superhydrophobic film. The exceptional superhydrophobic properties of the system permitted efficient magnetic movement, controllable simply by sliding a magnet. The magnetofluidic device successfully detected Salmonella in food samples using a label-free format, achieving high sensitivity (limit of detection = 10¹ CFU/mL), selectivity, and broad linearity (10¹ – 10⁹ CFU/mL). This device demonstrates straightforward fabrication, pump-free operation, and a portable platform, positioning it as a promising alternative for future semi-automated electrochemical biosensors in point-of-care applications.

Abstract

The growing demand for rapid, accurate, and accessible diagnostic tools has driven significant progress in biosensor technologies for medical applications. Our recent research centers on the development of advanced electrochemical and optical biosensors, particularly those built on paper-based and microfluidic platforms tailored for point-of-care diagnostics. In the electrochemical domain, we have engineered a variety of user-friendly and multiplexed devices for the detection of infectious diseases such as hepatitis B and C viruses (HBV, HCV), human immunodeficiency virus (HIV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and Mycobacterium tuberculosis (TB). These sensors integrate nanostructured electrodes, peptide nucleic acid (PNA) probes, G-quadruplex DNAzymes, and amplification-free detection strategies. Combined with microfluidic flow control, wireless circuitry, and smartphone interfaces, the platforms offer portable, rapid, and high-performance diagnostics with minimal sample handling. On the optical front, we have developed colorimetric and fluorescent biosensors for clinically important targets such as human papillomavirus (HPV) DNA, SARS-CoV-2 spike antigen, tuberculosis biomarkers, and cardiovascular indicators like C-reactive protein (CRP). These devices utilize gold nanoparticle-based signal enhancement, electroluminescent transducers, and smartphone-assisted readouts. Design innovations such as delayed lateral flow and enzyme-free amplification further enhance sensitivity without compromising usability. Collectively, our electrochemical and optical biosensors represent a powerful suite of next-generation tools for decentralized medical diagnostics. Their low cost, portability, and clinical relevance position them as promising solutions for real-world applications, particularly in resource-limited environments.

Abstract

The present research analyze the performance parameters of a surface plasmon resonance (SPR) biosensor such as sensitivity, detection accuracy, quality factor, and combined sensitivity factor as a function of graphene chemical potential in a metal/2D material/graphene multilayer system. The attenuated total reflection of SPR was studied as a function of the number of graphene sheets for different 2D materials (ZnO, MoS2 , MoSe2 , WSe2, WS2 ) and calculated using the transfer matrix method. It was found that there is a critical value of the chemical potential for which the performance parameters change their behavior abruptly for all type of 2D materials used in the biosensor configuration; this chemical potential value is called critical chemical potential. Furthermore, the number of graphene sheets have a strong effect on the performance parameters. Finally, an analytical expression for the sensitivity was deduced, which allows to explain their behavior for the different 2D materials used in the SPR biosensor. A bimetallic/2D materials/graphene biosensor’s results are also presented.

Abstract

A type of laser known as random lasers (RLs) represents a novel class of light sources that operate without conventional optical cavities. Instead, optical feedback was achieved through multiple scattering in a disordered gain medium. The result is laser-like emission that has high sensitivity to variations in the surrounding environment. The unique feedback mechanism not only enables the development of compact and cost-effective laser systems but also opens exciting possibilities in biosensing realms. RLs are well suited for detecting biomolecular interactions, due to their high sensitivity to changes in refractive index and scattering conditions. Therefore, making them excellent candidates for label-free, real-time sensing platforms. For applications in biosensing, the RLs emission characteristics such as threshold, intensity, and spectral linewidth can be modulated with the present of biological analytes. These changes offer detectable signatures that can be correlated to the specific biochemical events and therefore enabling the design of robust optical biosensors. Recent advances in open-cavity RL configurations further enhance their potential integration into microfluidics and flexible substrates, hence, supporting their deployment in portable diagnostic tools. Based on these principles, our work focuses on the development of ZnO nanorod-based random lasers as biosensing elements. ZnO is known as a wide-bandgap semiconductor (3.37 eV), having strong and efficient excitonic emissions at room temperature in the UV range, excellent biocompatibility, with versatile fabrication techniques. By tailoring the growth conditions, well-aligned ZnO nanorod arrays with optimized morphological, optical, and electrical properties can be achieved. These nanostructures show low-threshold and narrow random lasing emission and good response to environmental perturbations which are ideal for detecting biomolecular interactions. This study demonstrates that ZnO nanostructures, combined with the distinct advantages of random lasers, paves the way for innovative biosensing. The combination of nanophotonics and bio-sensing technologies hold promises for transdisciplinary applications in diagnostics and personalized healthcare.