Masoud Madadelahi

A highly sensitive and selective electrochemical sensor for Cu²⁺ ions was fabricated by modifying a glassy carbon electrode (GCE) with a CdS/rGO nanocomposite. The structural and morphological characteristics of the synthesized materials were thoroughly investigated using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. These analyses confirmed the synthesis of the CdS/rGO nanocomposite via a hydrothermal synthesis route. The electrochemical performance of the modified electrode was systematically evaluated using cyclic voltammetry (CV), differential pulse anodic stripping voltammetry (DPASV), and electrochemical impedance spectroscopy (EIS). The CdS/rGO-modified electrode exhibited enhanced electrocatalytic activity, with well-defined anodic and cathodic peak currents that demonstrated a linear relationship with the square root of the scan rate over the range of 50–250 mV s⁻¹. Under optimized conditions, the sensor demonstrated appropriate analytical performance over a Cu²⁺ concentration range of 10–100 nM, with a remarkably low limit of detection (LOD) of 2.83 nM. Furthermore, the sensor exhibited good selectivity toward Cu²⁺ in the presence of various interfering ions, along with good reproducibility and long-term operational stability. Its practical applicability was further demonstrated through the successful determination of Cu²⁺ ions in water samples and complex matrices, yielding satisfactory recovery values. These results highlight the potential of the CdS/rGO-based sensor as a reliable and sensitive platform for the practical electrochemical detection of Cu²⁺ ions.

Biopolymer core-shell microspheres play a crucial role in various biomedical applications, including drug delivery, tissue engineering, and diagnostics. These applications require microparticles with consistent, well-controlled size and precise shape fidelity. However, achieving high-throughput synthesis of size and shape-controlled core-shell biopolymer microgels remains a significant challenge. Herein, we present a one-step process for the high-throughput generation of monodisperse, luminescent, chitosan alginate core-shell microspheres by a novel manipulation of a centrifugal microfluidic device. We utilized the pH sensitivity of chitosan and the ionic gelation properties of alginate to create well-defined core-shell morphologies. To address particle merging issues and promote uniform particle size generation, we introduced an innovative pulsed mode operation in our centrifugal microfluidics device. We also incorporated fluorescent, nitrogen-functionalized graphene quantum dots into the core-shell structures, thereby rendering them useful for real-time imaging, which is necessary for diagnostic and therapeutic applications. To enhance biocompatibility, the alginate solution was supplemented with fish gelatin (FG). The resulting microspheres exhibited excellent structural integrity maintaining their core-shell structure after 15 days. Biocompatibility was demonstrated by C2C12 cell viability exceeding 88% after 15 days and by bacterial viability reaching the same percentage after 2 days. The system demonstrates considerable scalability, allowing for the consistent production of large quantities of microspheres without compromising functionality. The streamlined and efficient methodology simplifies the production process while unlocking new possibilities in targeted therapies, tissue regeneration, and diagnostics.

As a popular process in molecular-based diagnostics, polymerase chain reaction (PCR) can be employed for amplifying small amounts of DNA/RNA from different sources such as tissue, cells, peripheral blood and so on. Thanks to the unique physicochemical characteristics of nanomaterials and their progress, researchers have been encouraged to employ them as suitable candidates to address the PCR optimization challenges for enhancing efficiency, yield, specificity, and sensitivity. In nanoparticle-assisted PCR (nanoPCR), different nanoparticles (NPs) such as carbon nanotubes (CNTs), graphene, quantum dots (QDs), and gold (Au) might be used. Among different nanoPCR assays, photothermal PCR has emerged as a technique leveraging the excellent light absorption and heat conversion capabilities of nanomaterials. In addition to presenting recent advances in nanoPCR, this review also delves into the specific use of nanomaterials for photothermal PCR, including their applications in microfluidics as one of the best platforms for miniaturization of diagnostic techniques. Different types of NPs used in PCR are comprehensively examined, and detailed charts and tables are provided that outline features such as optimal concentration and size. The appropriate choice of nanomaterials for enhancing light conversion to heat in PCR applications is discussed. Finally, the related challenges and future trends are explored.

Centrifugal microfluidic platforms are highly regarded for their potential in multiplexing and automation, as well as their wide range of applications, especially in separating blood plasma and manipulating two-phase flows. However, the need to use stroboscopes or high-speed cameras for monitoring these tasks hinders the extensive use of these platforms in research and commercial settings. In this study, we introduce an innovative and cost-effective strategy for using an array of light-dependent resistors (LDRs) as optical sensors in microfluidic devices, particularly centrifugal platforms. While LDRs are attractive for their potential use as photodetectors, their bulky size frequently restricts their ability to provide high-resolution detection in microfluidic systems. Here, we use specific waveguides to direct light beams from narrow apertures onto the surface of LDRs. We integrated these LDRs into electrified Lab-on-a-Disc (eLOD) devices, with wireless connectivity to smartphones and laptops. This enables many applications, such as droplet/particle counting and velocity measurement, concentration analysis, fluidic interface detection in multiphase flows, real-time monitoring of sample volume on centrifugal platforms, and detection of blood plasma separation as an alternative to costly stroboscope devices, microscopes, and high-speed imaging. We used numerical simulations to evaluate various fluids and scenarios, which include rotation speeds of up to 50 rad/s and a range of droplet sizes. For the testbed, we used the developed eLOD device to analyze red blood cell (RBC) deformability and improve the automated detection of sickle cell anemia by monitoring differences in RBC deformability during centrifugation using the sensors’ signals. In addition to sickle cell anemia, this device has the potential to facilitate low-cost automated detection of other medical conditions characterized by altered RBC deformability, such as thalassemia, malaria, and diabetes.