Nanostructured Metal Oxide-Based Microfluidic Biosensors for Point-of-Care Diagnostics

The potential research on microfluidic devices for detection of biomolecules has recently intensified due to its application in point-of-care (POC) diagnostics for global health care. Early detection plays an imperative role to determine predisposition to disease (prevention) or the outcome of disease (monitoring and prognosis). There is a significant need for POC diagnostics devices as perceived from biohazard threats, the spread of infectious disease, home testing and monitoring. The POC diagnostics can provide a convenient and immediate response to a patient test sample. The POC diagnostics can be attained via use of transportable, portable, and handheld instruments such as blood glucometer, cholesterol meter etc. and test kits. It includes testing of blood or urine for pathogens, glucose, cholesterol, blood gas, coagulation, biomarkers, hemoglobin, pregnancy etc. Cheaper, smaller, faster, and smarter devices are the main merits of POC diagnostics for detection of various target analytes. A number of clinical biochemical studies such as blood gas, glucose/lactate/cholesterol, nucleic acid sequence analysis, proteins/peptides, combinatorial synthesis, toxicity monitoring, immunoassays, and forensic analysis are also focused areas for developing microfluidic biochips

Application of functionalized graphene oxide based biosensors for health monitoring: Simple graphene derivatives to 3D printed platforms

Biosensors hold great potential for revolutionizing personalized medicine and environmental monitoring. Their construction is the key factor which depends on either manufacturing techniques or robust sensing materials to improve efficacy of the device. Functional graphene is an attractive choice for transducing material due to its various advantages in interfacing with biorecognition elements. Graphene and its derivatives such as graphene oxide (GO) are thus being used extensively for biosensors for monitoring of diseases. In addition, graphene can be patterned to a variety of structures and is incorporated into biosensor devices such as microfluidic devices and electrochemical and plasmonic sensors. Among biosensing materials, GO is gaining much attention due to its easy synthesis process and patternable features, high functionality, and high electron transfer properties with a large surface area leading to sensitive point-of-use applications. Considering demand and recent challenges, this perspective review is an attempt to describe state-of-the-art biosensors based on functional graphene. Special emphasis is given to elucidating the mechanism of sensing while discussing different applications. Further, we describe the future prospects of functional GO-based biosensors for health care and environmental monitoring with a focus on additive manufacturing such as 3D printing

A self assembled monolayer based microfluidic sensor for urea detection

Urease (Urs) and glutamate dehydrogenase (GLDH) have been covalently co-immobilized onto a self-assembled monolayer (SAM) comprising of 10-carboxy-1-decanthiol (CDT) via EDC–NHS chemistry deposited onto one of the two patterned gold (Au) electrodes for estimation of urea using poly(dimethylsiloxane) based microfluidic channels (2 cm × 200 μm × 200 μm). The CDT/Au and Urs-GLDH/CDT/Au electrodes have been characterized using Fourier transform infrared (FTIR) spectroscopy, contact angle (CA), atomic force microscopy (AFM) and electrochemical cyclic voltammetry (CV) techniques. The electrochemical response measurement of a Urs-GLDH/CDT/Au bioelectrode obtained as a function of urea concentration using CV yield linearity as 10 to 100 mg dl−1, detection limit as 9 mg dl−1 and high sensitivity as 7.5 μA mM−1 cm−2

Nanostructured anatase-titanium dioxide based platform for application to microfluidics cholesterol biosensor

We report results of studies relating to the fabrication of a microfluidics cholesterol sensor based on nanocrystalline anatase-titanium dioxide (ant-TiO 2) film deposited onto indium tin oxide (ITO) glass. The results of response studies (optimized under the flow rate of 30 μl/min) conducted on cholesterol oxidase (ChOx) immobilized onto crystalline ant-TiO 2 nanoparticles (∼27 nm)/ITO microfluidics electrode reveal linearity as 1.3 to 10.3 mM and improved sensitivity of 94.65 μA/mM/cm 2. The observed low value of K m (0.14 mM) indicates high affinity of ChOx to cholesterol. No significant changes in current response of this microfluidics sensor are measured in the presence of different interferent

Highly efficient bienzyme functionalized nanocomposite-based microfluidics biosensor platform for biomedical application

This report describes the fabrication of a novel microfluidics nanobiochip based on a composite comprising of nickel oxide nanoparticles (nNiO) and multiwalled carbon nanotubes (MWCNTs), as well as the chip's use in a biomedical application. This nanocomposite was integrated with polydimethylsiloxane (PDMS) microchannels, which were constructed using the photolithographic technique. A structural and morphological characterization of the fabricated microfluidics chip, which was functionalized with a bienzyme containing cholesterol oxidase (ChOx) and cholesterol esterase (ChEt), was accomplished using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy. The XPS studies revealed that 9.3% of the carboxyl (COOH) groups present in the nNiO-MWCNT composite are used to form amide bonds with the NH 2 groups of the bienzyme. The response studies on this nanobiochip reveal good reproducibility and selectivity, and a high sensitivity of 2.2â.mA/mM/cm 2. This integrated microfluidics biochip provides a promising low-cost platform for the rapid detection of biomolecules using minute samples

Continuous in situ soil nitrate sensors: The importance of high‐resolution measurements across time and a comparison with salt extraction‐based methods

Soil NO3– affects microbial processes, plant productivity, and environmental N losses. However, the ability to measure soil NO3– is limited by labor‐intensive sampling and laboratory analyses. Hence, temporal variation in soil solution NO3– concentration is poorly understood. We evaluated a new potentiometric sensor that continuously measures soil solution NO3– concentration with unprecedented specificity due to a novel membrane that serves as a barrier to interfering anions. First, we compared sensor and salt extraction‐based measurements of soil NO3– in well‐controlled laboratory conditions. Second, using 60 d of in situ soil NO3– measurements every 10 s, we quantified temporal variation and the effect of sampling frequency on field estimations of mean daily NO3– concentration both within and across days. In the laboratory, sensors measured soil NO3– concentration without significant difference from theoretical adjusted soil NO3– concentration or conventional salt extraction‐based methods. In the field, the sensors demonstrated no within‐day pattern in soil NO3– concentration, although individual measurements within a day differed by as much as 20% from the daily mean. Across days, when soil solution NO3– was dynamic (early spring) and sampling frequency was \u3e5 d, estimates of mean daily NO3– concentration were \u3e20% from the actual mean daily concentration. In situ soil sensors offer potential to improve fundamental and applied sciences. However, in most situations, sensors will measure soil properties in a different manner than conventional salt‐extract soil sampling‐based approaches. Research will be required to interpret sensor measurements and optimize sensor deployment

Correlation between slump, VeBe and compaction factor of concrete containing shredded PET bottles, manufactured sand (M-sand) and river sand as fine aggregate

This paper investigates the effects of the properties of fresh concrete incorporating shredded Polyethylene Terephthalate (PET) bottles and Manufactured Sand (M-sand) together as fine aggregates replacement in concrete mixtures. The investigation to determine the correlation of the fresh properties of concrete were mainly experimental based and the experiments involved were Slump Test, VeBe Test and Compaction Factor Test. There were two different concrete batches were prepared, in which the first batch was partially replaced by Msand and the second batch was partially replaced by M-sand and shredded PET bottles as fine aggregate replacements. The proportion of M-sand content and M-sand with shredded PET bottles were 25%, 50%, 75% and 100% (for M-sand) and 1.5% proportion of shredded PET bottles respectively. The mix design was prepared in accordance to the Department of Environment (DOE) method and utilizes M30 as the Class of Concrete. A novel empirical relationship between slump, VeBe, and compaction factor for the shredded PET bottles and MSand based M30 concrete was proposed. The outcomes of this research has proven beneficial to the construction industries as the utilisation of waste and recycled materials has the potential for sustainable construction

Participatory and Institutional Approaches to Agricultural Climate Services: A South and Southeast Asia Regional Technical & Learning Exchange

In order to share experience and boost capacity in agricultural climate services, a three-day workshop titled ‘Participatory and Institutional Approaches to Agricultural Climate Services Development: A South and South East Asia Regional Technical and Learning exchange” was held between September 17-19, 2017, in Dhaka, Bangladesh, with more than 50 leaders in agricultural climate services from 11 countries attending. The workshop was sponsored by the U.S. Agency for International Development (USAID) behalf of the Climate Services for Resilient Development (CSRD). The workshop was organized by the International Maize and Wheat Improvement Center (CIMMYT) alongside the SERVIR and Climate Services Support Activity and CSRD South Asian partners