The memristive effect as a novelty in drug monitoring

Development of nanobiosensor for therapeutic drug monitoring in personalized cancer treatment approach

Docetaxel is one of the most effective and safe chemotherapy drugs according to the World Health Organization, but its clinical use has been discontinued due to its various side effects. To reduce these side effects, the amount of docetaxel drug should be kept at the most effective level, it should be monitored in body fluids. Due to the limitations of traditional analytical methods used for this purpose, such as expensive and low sensitivity, labor-intensive and time-consuming complex preliminary preparation, efficient methods are required for the determination of the docetaxel level in the body. The increasing demand for the development of personalized therapy has recently spurred significant research into biosensors for the detection of drugs and other chemical compounds. In this study, an electrochemical-based portable nanobiosensor system was developed for the rapid, low-cost, and sensitive determination of docetaxel. In this context, mg-p(HEMA)-IMEO nanoparticles to be used as nanobiosensor bioactive layer was synthesized, characterized, and docetaxel determination conditions were optimized. According to the results obtained, the developed nanobiosensor system can detect docetaxel with a sensitivity of 2.22 mg/mL in a wide calibration range of 0.25-10 mg/mL, in only 15 min, in mixed media such as commercially available artificial blood serum and urine. determined. We concluded that the developed nanobiosensor system can be successfully used in routine drug monitoring as a low-cost biomedical device capable of direct, rapid, and specific drug determination within the scope of personalized treatment, providing point-of-care testing.

A comprehensive review on the biomedical frontiers of nanowire applications

This comprehensive review examines the immense capacity of nanowires, nanostructures characterized by unbounded dimensions, to profoundly transform the field of biomedicine. Nanowires, which are created by combining several materials using techniques such as electrospinning and vapor deposition, possess distinct mechanical, optical, and electrical properties. As a result, they are well-suited for use in nanoscale electronic devices, drug delivery systems, chemical sensors, and other applications. The utilization of techniques such as the vapor-liquid-solid (VLS) approach and template-assisted approaches enables the achievement of precision in synthesis. This precision allows for the customization of characteristics, which in turn enables the capability of intracellular sensing and accurate drug administration. Nanowires exhibit potential in biomedical imaging, neural interfacing, and tissue engineering, despite obstacles related to biocompatibility and scalable manufacturing. They possess multifunctional capabilities that have the potential to greatly influence the intersection of nanotechnology and healthcare. Surmounting present obstacles has the potential to unleash the complete capabilities of nanowires, leading to significant improvements in diagnostics, biosensing, regenerative medicine, and next-generation point-of-care medicines.

Review of Electrochemically Synthesized Resistive Switching Devices: Memory Storage, Neuromorphic Computing, and Sensing Applications

Resistive-switching-based memory devices meet most of the requirements for use in next-generation information and communication technology applications, including standalone memory devices, neuromorphic hardware, and embedded sensing devices with on-chip storage, due to their low cost, excellent memory retention, compatibility with 3D integration, in-memory computing capabilities, and ease of fabrication. Electrochemical synthesis is the most widespread technique for the fabrication of state-of-the-art memory devices. The present review article summarizes the electrochemical approaches that have been proposed for the fabrication of switching, memristor, and memristive devices for memory storage, neuromorphic computing, and sensing applications, highlighting their various advantages and performance metrics. We also present the challenges and future research directions for this field in the concluding section.

Fluorescence-Enhanced Microfluidic Biosensor Platform Based on Magnetic Beads with Highly Stable ZnO Nanorods for Biomarker Detection

Existing affinity-based fluorescence biosensing systems for monitoring of biomarkers often utilize a fixed solid substrate immobilized with capture probes limiting their use in continuous or intermittent biomarker detection. Furthermore, there have been challenges of integrating fluorescence biosensors with a microfluidic chip and low-cost fluorescence detector. Herein, we demonstrated a highly efficient and movable fluorescence-enhanced affinity-based fluorescence biosensing platform that can overcome the current limitations by combining fluorescence enhancement and digital imaging. Fluorescence-enhanced movable magnetic beads (MBs) decorated with zinc oxide nanorods (MB-ZnO NRs) were used for digital fluorescence-imaging-based aptasensing of biomolecules with improved signal-to-noise ratio. High stability and homogeneous dispersion of photostable MB-ZnO NRs were obtained by grafting bilayered silanes onto the ZnO NRs. The ZnO NRs formed on MB significantly improved the fluorescence signal up to 2.35 times compared to the MB without ZnO NRs. Moreover, the integration of a microfluidic device for flow-based biosensing enabled continuous measurements of biomarkers in an electrolytic environment. The results showed that highly stable fluorescence-enhanced MB-ZnO NRs integrated with a microfluidic platform have significant potential for diagnostics, biological assays, and continuous or intermittent biomonitoring.

Tunable Switching Behavior of GO-Based Memristors Using Thermal Reduction

This work reports on the fabrication of a novel planar reduced graphene oxide (rGO) memristor (MR) device. For the first time in the literature, the MR tunable resistive switching behavior is controlled by the GO reduction time at a constant temperature. The device is fabricated using standard microfabrication techniques on a flexible cyclic olefin copolymer substrate (COC). Thermal reduction of the GO layer at low temperatures (100 °C) avoids the drawbacks of chemical reduction methods such as toxicity and electrode metal damage during fabrication, while allowing for fine-tuning of the MR’s switching behavior. The device has analog switching characteristics, with a range of different resistance states. By taking advantage of the slow nature of GO thermal annealing, the switching properties of the rGO memristors can be precisely controlled by adjusting the reduction period. At short annealing times (i.e., T < 20 h), the devices switch from high to low resistance states, while at longer annealing times the switching behavior is reversed, with the device switching from low to high resistance states (LRS to HRS). Resistive switching occurs as a result of the diffusion and removal of the oxygen functional groups in the GO film caused by Joule heating induced by the electric current. Complete electrical characterization tests are presented along with wettability and X-ray diffraction (XRD) tests. This work opens a new vision for realizing rGO-based MR devices with tunable switching properties, broadening the application horizon of the device.

Towards wearable and implantable continuous drug monitoring: A review

Continuous drug monitoring is a promising alternative to current therapeutic drug monitoring strategies and has a strong potential to reshape our understanding of pharmacokinetic variability and to improve individualised therapy. This review highlights recent advances in biosensing technologies that support continuous drug monitoring in real time. We focus primarily on aptamer-based biosensors, wearable and implantable devices. Emphasis is given to the approaches employed in constructing biosensors. We pay attention to sensors' biocompatibility, calibration performance, long-term characteristics stability and measurement quality. Last, we discuss the current challenges and issues to be addressed in continuous drug monitoring to make it a promising, future tool for individualised therapy. The ongoing efforts are expected to result in fully integrated implantable drug biosensing technology. Thus, we may anticipate an era of advanced healthcare in which wearable and implantable biochips will automatically adjust drug dosing in response to patient health conditions, thus enabling the management of diseases and enhancing individualised therapy.

Aptamer-guided extracellular vesicle theranostics in oncology

In the past decade, the study of exosomes, nanosized vesicles (50-150 nm) released into the extracellular space via the fusion of multivesicular bodies with the plasma membrane, has burgeoned with impressive achievements in theranostics applications. These nanosized vesicles have emerged as key players in homeostasis and in the pathogenesis of diseases owing to the variety of the cargos they can carry, the nature of the molecules packaged inside the vesicles, and the robust interactions between exosomes and target cells or tissues. Accordingly, the development of exosome-based liquid biopsy techniques for early disease detection and for monitoring disease progression marks a new era of precision medicine in the 21st century. Moreover, exosomes possess intrinsic properties - a nanosized structure and unique "homing effects" - that make them outstanding drug delivery vehicles. In addition, targeted exosome-based drug delivery systems can be further optimized using active targeting ligands such as nucleic acid aptamers. Indeed, the aptamers themselves can function as therapeutic and/or diagnostic tools based on their attributes of unique target-binding and non-immunogenicity. This review aims to provide readers with a current picture of the research on exosomes and aptamers and their applications in cancer theranostics, highlighting recent advances in their transition from the bench to the clinic.

Amperometric Aptasensor for Amyloid-β Oligomer Detection by Optimized Stem-Loop Structures with an Adjustable Detection Range

Amyloid-β oligomers (AβO) have become representative biomarkers for early diagnosis of Alzheimer's disease. Here, we report on an aptasensor based on stem-loop probes for sensitive and specific detection of AβO by an amperometric transducer principle using alternating current voltammetry (ACV). Stem-loop probes with redox-active moieties are immobilized on a gold substrate as a receptor element. The signal transduction mechanism relies on redox ferrocene (Fc) reporting via charge transfer on a molecular recognition event involving a conformational change of the molecular beacon. The stem-loop structures were optimized by considering the aptamers' stem length, spacer, and different ferrocene terminals. In addition, the sensor assembly and signal recording including aptamer concentration and ACV frequency dependence are discussed. Using the optimized stem-loop probe (B-3' Fc), the aptasensor showed a decrease of the Fc peak current induced by AβO binding within the broad concentration range spanning 6 orders of magnitude. Furthermore, the detection limit of the sensor can be further decreased by optimizing the ACV frequency, however at the cost of a narrowed detection range. In this work, a label-free electrochemical aptasensor is demonstrated, which facilitates the quantification of the concentration of AβO with high selectivity and subpicomolar sensitivity, which may be conducive to improving the diagnosis and pharmacology studies of Alzheimer's disease.

Nanowire Sensors in Cancer

In 2006, the group of Dr C.M. Lieber pioneered the field of nanowire sensors by fabricating devices for the ultra-sensitive label-free detection of biological macromolecules. Since then, nanowire sensors have demonstrated their ability to detect cancer-associated analytes in peripheral blood, tumor tissue, and the exhaled breath of cancer patients. These innovative developments have marked a new era with unprecedented detection performance, capable of addressing crucial needs such as cancer diagnosis and monitoring disease progression and patient response to therapy. The ability of nanowire sensors to identify molecular features of patient tumor represents a first step toward precision medicine, and their integration into portable devices has the potential to revolutionize cancer diagnosis and patient monitoring.