This work focuses on the development of an electrochemiluminescent nanostructured DNA biosensor for SARS-CoV-2 detection. Gold nanomaterials (AuNMs), specifically, a mixture of gold nanotriangles (AuNTs) and gold nanoparticles (AuNPs), are used to modified disposable electrodes that serve as an improved nanostructured electrochemiluminescent platform for DNA detection. Carbon nanodots (CDs), prepared by green chemistry, are used as coreactants agents in the [Ru(bpy)
3
]
2+
anodic electrochemiluminescence (ECL) and the hybridization is detected by changes in the ECL signal of [Ru(bpy)
3
]
2+
/CDs in combination with AuNMs nanostructures. The biosensor is shown to detect a DNA sequence corresponding to SARS-CoV-2 with a detection limit of 514 aM.
With the rising diabetic population, the demand for glucose
sensing
devices has also been on an increasing trend. Accordingly, the field
of glucose biosensors for diabetes management has witnessed tremendous
scientific and technological advancements since the introduction of
the first enzymatic glucose biosensor in the 1960s. Among these, electrochemical
biosensors hold considerable potential for tracking dynamic glucose
profiles in real time. The recent evolution of wearable devices has
opened opportunities to use alternative body fluids in a pain-free,
noninvasive or minimally invasive manner. This review aims to present
a comprehensive report about the status and promise of wearable electrochemical
sensors for on-body glucose monitoring. We start by highlighting the
importance of diabetes management and how sensors can contribute toward
its effective monitoring. We then discuss the electrochemical glucose
sensing mechanisms, evolution of such glucose sensors over time, different
versions of wearable glucose biosensors targeting various biofluids,
and multiplexed wearable sensors toward optimal diabetes management.
Finally, we focus on the commercial aspects of wearable glucose biosensors,
starting with existing continuous glucose monitors, followed by other
emerging sensing technologies, and concluding with highlighting the
key prospects toward personalized diabetes management in connection
to an autonomous closed-loop artificial pancreas.
Sweat is an important biofluid presents in the body since it regulates the internal body temperature, and it is relatively easy to access on the skin unlike other biofluids and contains several biomarkers that are also present in the blood. Although sweat sensing devices have recently displayed tremendous progress, most of the emerging devices primarily focus on the sensor development, integration with electronics, wearability, and data from in vitro studies and short‐term on‐body trials during exercise. To further the advances in sweat sensing technology, this review aims to present a comprehensive report on the approaches to access and manage sweat from the skin toward improved sweat collection and sensing. It is begun by delineating the sweat secretion mechanism through the skin, and the historical perspective of sweat, followed by a detailed discussion on the mechanisms governing sweat generation and management on the skin. It is concluded by presenting the advanced applications of sweat sensing, supported by a discussion of robust, extended‐operation epidermal wearable devices aiming to strengthen personalized healthcare monitoring systems.
The highly packed cetyltrimethylammonium bromide bilayer on the surface of gold nanorods synthesized by the seed-mediated procedure hampers the complete ligand exchange under experimental conditions that preserves the stability of the dispersions.
β-Hydroxybutyrate (HB) is one of the main physiological
ketone
bodies that play key roles in human health and wellness. Besides their
important role in diabetes ketoacidosis, ketone bodies are currently
receiving tremendous attention for personal nutrition in connection
to the growing popularity of oral ketone supplements. Accordingly,
there are urgent needs for developing a rapid, simple, and low-cost
device for frequent onsite measurements of β-hydroxybutyrate
(HB), one of the main physiological ketone bodies. However, real-time
profiling of dynamically changing HB concentrations is challenging
and still limited to laboratory settings or to painful and invasive
measurements (e.g., a commercial blood ketone meter). Herein, we address
the critical need for pain-free frequent HB measurements in decentralized
settings and report on a reliable noninvasive, simple, and rapid touch-based
sweat HB testing and on its ability to track dynamic HB changes in
secreted fingertip sweat, following the intake of commercial ketone
supplements. The new touch-based HB detection method relies on an
instantaneous collection of the fingertip sweat at rest on a porous
poly(vinyl alcohol) (PVA) hydrogel that transports the sweat to a
biocatalytic layer, composed of the β-hydroxybutyrate dehydrogenase
(HBD) enzyme and its nicotinamide adenine dinucleotide (NAD+) cofactor, covering the modified screen-printed carbon working electrode.
As a result, the sweat HB can be measured rapidly by the mediated
oxidation reaction of the nicotinamide adenine dinucleotide (NADH)
product. A personalized HB dose–response relationship is demonstrated
within a group of healthy human subjects taking commercial ketone
supplements, along with a correlation between the sweat and capillary
blood HB levels. Furthermore, a dual disposable biosensing device,
consisting of neighboring ketone and glucose enzyme electrodes on
a single-strip substrate, has been developed toward the simultaneous
touch-based detection of dynamically changing sweat HB and glucose
levels, following the intake of ketone and glucose drinks.
Gold nanotriangles (AuNTs) functionalized with dithiolated oligonucleotides have been employed to develop an amplification-free electrochemical biosensor for SARS-CoV-2 in patient samples. Gold nanotriangles, prepared through a seed-mediated growth method and exhaustively characterized by different techniques, serve as an improved electrochemical platform and for DNA probe immobilization. Azure A is used as an electrochemical indicator of the hybridization event. The biosensor detects either single stranded DNA or RNA sequences of SARS-CoV-2 of different lengths, with a low detection limit of 22.2 fM. In addition, it allows to detect point mutations in SARS-CoV-2 genome with the aim to detect more infective SARS-CoV-2 variants such as Alpha, Beta, Gamma, Delta, and Omicron. Results obtained with the biosensor in nasopharyngeal swab samples from COVID-19 patients show the possibility to clearly discriminate between non-infected and infected patient samples as well as patient samples with different viral load. Furthermore, the results correlate well with those obtained by the gold standard technique RT-qPCR, with the advantage of avoiding the amplification process and the need of sophisticated equipment.
Graphical abstract
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