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The level of cortisol can reflect people's psychological stress, help diagnose adrenal gland diseases, and is also related to several mental diseases. In this study, we developed a cortisol monoclonal antibody-oriented approach to modify an immunosensor for wearable label-free and persistent sweat cortisol detection. On such an antibody-oriented immunosensor, the fragment crystallizable (Fc) region is partially inserted within the metal-organic framework (MOF), and antibody-binding regions of the cortisol monoclonal antibody (C mab ) were exposed on the MOF surface via selective growth and self-assembly. Such ordered and oriented embedding of antibodies in the MOF resulted in excellent antibody activity and improved stability and antigen-binding capacity. We also engineered the full integrated system for on-body sweat cortisol biosensing performance in several volunteers, and the results indicated that this wearable sensor is suitable for practical cortisol detection with a good linear detection range from 1 pg/mL to 1 μg/mL with a lower limit of detection of 0.26 pg/mL. Moreover, the wearable sensor demonstrated good persistence in detecting cortisol, with only 4.1% decay after 9 days of storage. The present work represents a simple oriented antibody assembling approach to improve the stability of antibodies, providing an important step toward long-term continuous sweat biomarker detection.

The chemistry of the metal-organic frameworks (MOFs) coating may affect the biological functionality of the encapsulated biomacromolecules in harsh environment. Enzymes encapsulated in hydrophilic MAF-7 can retain high activity in harsh environment. We conducted this study to prepare a non-invasive wearable uircase@MAF-7-based electrochemical sensor that can achieve accurate and sensitive detection of UA levels in sweat by integrating a flexible microfluidic chip and wireless electronic readout device. The flexible microfluidic chip enabled an easy and effective collection of sweat samples. MAF-7 protected enzyme activity by encapsulating uricase. The uricase@MAF-7-based electrochemical sensor enabled the highly sensitive detection of UA in the concentration range of 2 μM-70 μM with a detection limit of as low as 0.34 μM. Additionally, we evaluated the utility of the sensor for monitoring UA levels in real sweat samples by means of a high purine dietary challenge. This personalized wearable sweat sensing device has a potential to be used for monitoring disease-related metabolites in daily life., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Metal–organic frameworks (MOFs) are novel inorganic–organic hybridized crystals with a wide range of applications. In the last twenty years, fluorescence sensing based on MOFs has attracted much attention. MOFs can exhibit luminescence from metal nodes, ligands or introduced guests, which provides an excellent fluorescence response in sensing. However, single-signal emitting MOFs are susceptible to interference from concentration, environment, and excitation intensity, resulting in poor accuracy. To overcome the shortcomings, dual-emission MOF-based ratiometric fluorescence sensors have been proposed and rapidly developed. In this review, we first introduce the luminescence mechanisms, synthetic methods, and detection mechanisms of dual-emission MOFs, highlight the strategies for constructing ratiometric fluorescence sensors based on dual-emission MOFs, and classify them into three categories: intrinsic dual-emission and single-emission MOFs with luminescent guests, and non-emission MOFs with other luminescent materials. Then, we summarize the recent advances in dual-emission MOF-based ratiometric fluorescence sensors in various analytical industries. Finally, we discuss the current challenges and prospects for the future development of these sensors. [ABSTRACT FROM AUTHOR]

"Green Synthesis" has been broadly applied in drug synthesis and nanomaterial preparation. The integration of automated micro‐synthesis and high‐throughput screening systems is a key way to achieve the goal of green manufacturing. Here, a one‐click green synthesis platform is designed that integrates droplets arrays‐based micro‐synthesis for Raman enhancement performance high‐throughput screening of MNPs@Cu‐MOF (AuNPs@, AgNPs@, PtNPs@Cu‐MOF) under room temperature and normal pressure. The fully integrated ultrasound units can achieve rapid multi‐component mixing in the droplet array systems, and significantly accelerate materials growth as well as enhance encapsulation of noble metal nanoparticles into Cu‐MOF structures. Based on such integrated systems, structures with high Raman enhancement performance can be high‐throughput evaluation and easily screened out. The results indicated that the AgNPs@Cu‐MOF exhibited the best Raman enhancement performance, which is ≈8 times higher than pure AgNPs. Such a green and integrated platform provides a way for automated multi‐type composites fabrication, which can be expanded to multiple fields in the future via combined robotic platforms and artificial intelligence technology. [ABSTRACT FROM AUTHOR]

Many studies have focused on effective ways to exploit enzyme immobilization on an electrode surface to help improve the performance of enzymatic electrochemical biosensors. Herein, a novel glucose sensor was fabricated by immobilizing glucose oxidase (GOx) onruthenium‐based conjugated polymer (CP) and metal‐organic framework (MOF) nanocomposites. This has not only reduced the applied potential to 0.2 V (vs. Ag/AgCl), but also improved the effective surface area for enzyme immobilization.PPG@Ru@UiO‐66‐NH2 was tailored by controlled chemical synthesis from a pre‐synthesized water‐soluble conjugated polymer (poly(N‐phenylglycine)) and metal‐organic framework (UiO‐66‐NH2). The resulting nanocomposites were characterized using Fourier transform infrared spectroscopy, X‐ray fluorescence, scanning electron microscopy, and cyclic voltammetry. The PPG@Ru@UiO‐66‐NH2/GOx coated electrodedisplayed a linear measurementrange for glucose from 1 mM to 10 mM, with a sensitivity of 45.92 μA ⋅ mM−1cm−1 and limit of detection of5 μM(S/N=3). Furthermore, the practical application of the fabricatedglucosesensor was tested in simulative blood samples with satisfactoryaccuracy. This approach alsoopens a new door for applications regarding both enzymatic electrochemical biosensors and enzymatic biofuel cells (EBFCs). [ABSTRACT FROM AUTHOR]

Levodopa (L -dopa) is an effective medication for Parkinson's disease. However, excess intake from overdose or the intake of natural sources of L -dopa can be dangerous, causing, for example, tardive dyskinesia. Therefore, in medicated individuals, it is important to monitor the levels of L -dopa in the body. In this paper, we report a simple, wearable, noninvasive, and portable metal−organic framework (MOF)-based electrochemical sensor with integrated enzymes for monitoring the concentration of levodopa in sweat, which can be used as a proxy for L -dopa levels in the body. Zeolitic imidazolate framework/graphene oxide (ZIF-8/GO) composites were prepared by the in-situ growth of ZIF-8 nanoparticles on the surface of GO, and, subsequently, tyrosinase was loaded onto the composite to yield the sensor. Integration with a wireless electronic circuit enabled communication between the sensor and a smartphone application for continuous analysis. The sensor was found to have a wide linear response range from 1 to 95 µM, a low limit of detection of 0.45 µM, satisfactory reproducibility, and excellent selectivity. In addition, the sensor showed high sensitivity and good stability as a result of the anchoring of the enzyme. Thus, the sensor shows promise for continuous, noninvasive point-of-care drug monitoring and management. • Noninvasive electrochemical sensor for levodopa determination in sweat developed. • Anchoring tyrosinase on ZIF-8/graphene oxide increases stability and active sites. • Linear electrochemical response over wide concentration range (1–95 µM). • Low limit of detection of 0.45 µM. • Continuous wireless monitoring of volunteers possible during exercise. [ABSTRACT FROM AUTHOR]