An effective hydroxylation route for a highly sensitive glucose sensor using APTES/GOx functionalized AlGaN/GaN high electron mobility transistor

Status and Prospects of Heterojunction-Based HEMT for Next-Generation Biosensors

High electron mobility transistor (HEMT) biosensors hold great potential for realizing label-free, real-time, and direct detection. Owing to their unique properties of two-dimensional electron gas (2DEG), HEMT biosensors have the ability to amplify current changes pertinent to potential changes with the introduction of any biomolecules, making them highly surface charge sensitive. This review discusses the recent advances in the use of AlGaN/GaN and AlGaAs/GaAs HEMT as biosensors in the context of different gate architectures. We describe the fundamental mechanisms underlying their operational functions, giving insight into crucial experiments as well as the necessary analysis and validation of data. Surface functionalization and biorecognition integrated into the HEMT gate structures, including self-assembly strategies, are also presented in this review, with relevant and promising applications discussed for ultra-sensitive biosensors. Obstacles and opportunities for possible optimization are also surveyed. Conclusively, future prospects for further development and applications are discussed. This review is instructive for researchers who are new to this field as well as being informative for those who work in related fields.

Transdermal Insulin Delivery and Microneedles-based Minimally Invasive Delivery Systems

Diabetes has become a serious threat to human health, causing death and pain to numerous patients. Transdermal insulin delivery is a substitute for traditional insulin injection to avoid pain from the injection. Transdermal methods include non-invasive and invasive methods. As the non-invasive methods could hardly get through the stratum corneum, minimally invasive devices, especially microneedles, could enhance the transappendageal route in transcutaneous insulin delivery, and could act as connectors between the tissue and outer environment or devices. Microneedle patches have been in quick development in recent years and with different types, materials and functions. In those patches, the smart microneedle patch could perform as a sensor and reactor responding to glucose to regulate the blood level. In the smart microneedles field, the phenylboronic acid system and the glucose oxidase system have been successfully applied on the microneedle platform. Insulin transdermal delivery strategy, microneedles technology and smart microneedles' development would be discussed in this review.

1T and 2H heterophase MoS2for enhanced sensitivity of GaN transistor-based mercury ions sensor

We report significantly enhanced sensitivity of AlGaN/GaN-based high electron mobility transistor (HEMT) sensor by the targeted synthesis of IT and 2H coexisting phase MoS₂and applying the gate bias voltage. The HEMT structures on Si (111) substrates were used for the detection of Hg²⁺ions. The optimum sensitive regime in terms ofV_GSandV_DSof the sensor was investigated by keeping the drain source voltageV_DSconstant at 2 V and by only varying the gate bias voltageV_GSfrom 0 to 3 V. The strongest sensing response obtained from the device was around 0.547 mA ppb^-1atV_GS = 3 V, which is 63.7% higher in comparison to the response achieved at 0 V which shows a sensing response of around 0.334 mA ppb^-1. The current response depicts that the fabricated device is very sensitive and selective towards Hg²⁺ions. Moreover, the detection limit of our sensor at 3 V was calculated around 6.21 ppt, which attributes to the strong field created between the gate electrode and the HEMT channel due to the presence of 1T metallic phase in synthesized MoS₂, indicating that the lower detection limits are achievable in adequate strong fields.

Designing DNA probe from HPV 18 and 58 in the E6 region for sensing element in the development of genosensor-based gold nanoparticles

The E6 region has higher protuberant probability annealing than consensus probe focusing on another region in the human papillomavirus (HPV) genome in terms of detection and screening method. Here, we designed the first multiple virus single-stranded deoxyribonucleic acid (ssDNA) for multiple detections in an early phase of screening for cervical cancer in the E6 region and became a fundamental evolution of detection electrochemical HPV biosensor. Gene profiling of the virus ssDNA sequences has been carried by high-end bioinformatics tools such as GenBank, Basic Local Alignment Searching Tools (BLAST), and Clustal OMEGA in a row. The output from bioinformatics tools resulted in 100% of similarities between our virus ssDNA probe and HPV complete genome in the databases. The cross-validation between HPV genome and our designed virus ssDNA provided high specificity and selectivity during screening methods compared with Pap smear. The DNA probe for HPV 18, 5' COOH-GAT CCA GAA GGT ACA GAC GGG GAG GGC ACG 3', while 5'COOH-GGG CGC TGT GCA GTG TGT TGG AGA CCC CGA3' as DNA probe for HPV 58 designed with 66.77% guanine (G) and cytosine (C) content for both. Our virus ssDNA probe for the HPV biosensor promises high sensitivity, specificity, selectivity, repeatability, low fluid consumption, and will be useful in mini-size diagnostic devices for cervical cancer detection.