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Open-channel droplet arrays have attracted much attention in the fields of biochemical analysis, biofluid monitoring, biomarker recognition and cell interactions, as they have advantages with regard to miniaturization, parallelization, high-throughput, simplicity and accessibility. Such droplet arrays not only improve the sensitivity and accuracy of a biosensor, but also do not require sophisticated equipment or tedious processes, showing great potential in next-generation miniaturized sensing platforms. This review summarizes typical examples of open-channel microdroplet arrays and focuses on diversified biosensing integrated with multiple signal-output approaches (fluorescence, colorimetric, surface-enhanced Raman scattering (SERS), electrochemical, etc.). The limitations and development prospects of open-channel droplet arrays in biosensing are also discussed with regard to the increasing demand for biosensors. [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]

Wearable sweat sensors with various sensing systems can provide noninvasive medical diagnostics and healthcare monitoring. Here, we demonstrate a wearable microfluidic nanoplasmonic sensor capable of refreshable and portable recognition fingerprint information of targeted biomarkers including urea, lactate, and pH in sweat. A miniature, thin plasmonic metasurface with homogeneous mushroom-shaped hot spots and high surface-enhanced Raman scattering (SERS) activity is designed and integrated into a microfluidics platform. Compared to conventional wearable SERS platforms with the risk of mixed effect between new and old sweat, the microfluidic SERS system allows sweat administration in a controllable and high temporal-resolution fashion, providing refreshable SERS analysis. We use a portable and customized Raman analyzer with a friendly human-machine interface for portable recognition of the spectroscopic signatures of sweat biomarkers. This study integrates epidermal microfluidics with portable SERS molecular recognition, presenting a controllable, handy, and dynamical biofluid sensing system for personalized medicine. [ABSTRACT FROM AUTHOR]

The bioinspired micropatterns exhibit outstanding capacity in controlling and patterning microdroplets, which have offered new functionalities and possibilities towards a wide variety of emerging biological and biomedical applications. By taking the advantages of the microdroplet anchoring ability, enrichment ability, and the accessibility of such bioinspired micropatterns, the selected topic mainly focuses on the important aspects related to (super)wettable surfaces and their emerging sensing applications (DNA, miRNA, proteins, etc.) by combining them with multiple signal output approaches (fluorescence, colorimetric, SERS, electrochemical, etc.). In the end, we also provide a personal perspective on the future development, and address the remaining challenges in the commercialization of (super)wettable micropatterns towards biosensing. [ABSTRACT FROM AUTHOR]

A nanodendritic gold/graphene-based biosensor that can perform fluorescence, SERS and electrochemical tri-modal miRNA detection in a single microdroplet has been developed. The biosensor was used to successfully perform tri-modal quantitative trace miRNA-375 detection, which enormously reduces false positive readings caused by interference and ambiguous signals, and has significant implications for use in precise physiological and pathological diagnosis. [ABSTRACT FROM AUTHOR]

• A target-triggered assembly strategy for Raman imaging of dual cancer biomarkers. • Two detection pathways are independent to produce strong SERS signals. • A potential tool to monitor the expression level of TE and mir-21 in different cell. Imaging multiple classes of intracellular cancer biomarkers provides invaluable insight into the tumor progression and allows cancer diagnosis at the molecular level. The challenge is to develop sensitive, selective and reliable methods for simultaneously imaging different types of cancer biomarkers at low concentrations. Herein, we demonstrated a target-triggered regioselective assembly strategy of plasmonic nanoprobes for dual Raman imaging of microRNA-21 (mir-21) and telomerase (TE) in cells. In the presence of TE, the intense signal of Raman reporter DTNB locating at the "hot spots" of end assembly probes (Au nanoparticles anchored on the terminal of Au nanorods) become weak once the TE triggers the dissociation of end assembly probes and release the DTNB-modified Au nanoparticles from the Au nanorods. Target mir-21 can trigger catalytic hairpin assembly amplification as catalysts and results in the formation of side nanoassemblies that Raman reporter Rox-modified Au nanoparticles anchored onto the side surface of Au nanorods, leading to enhancement in Rox signal. The two independent pathways can efficiently localize target analytes toward "hot spots" to produce strong, amplified SERS signals for the expression level and the dynamic change of mir-21 and TE in different cell lines, providing a potential tool for cancer diagnosis and progression monitor. [ABSTRACT FROM AUTHOR]

The development of biosensors with high sensitivity and low-detection limits provides a new direction for medical and personal care. Graphene and graphene derivatives have been used to prepare various types of biosensors due to their excellent sensing performance (e.g., high specific surface area, extraordinary electronic properties, electron transport capabilities and ultrahigh flexibility). This perspective review focuses on graphene-based biosensors for quantitative detection of cancer-related biomarkers such as DNA, miRNA, small molecules and proteins by integrating with different signal outputting approaches including fluorescent, electrochemistry, surface plasmon resonance, surface enhanced Raman scattering, etc. The article also discussed their challenges and potential solutions along with future prospects. [ABSTRACT FROM AUTHOR]

Urinalysis is an effective strategy to non-invasively evaluate human health, and surface-enhanced Raman scattering (SERS) may be a powerful technique for use in detecting analytes in urine. Herein, we report a wearable diaper sensor based on a handheld Raman spectrometer for use in the simple, label-free identification of biomolecules (urea, creatinine, and bilirubin) in urine. The raspberry-shaped Au substrate formed on the surface of an Si wafer provides plasmonic enhancement of the SERS signals, with an excellent uniformity and stability. The SERS sensor combines the advantages of flexibility, portability, and multifunctional detection and may be used in identifying multiple analytes in urine. The sensor exhibits high sensitivities in detecting urea, creatinine, and bilirubin, with respective detection limits of 4.17 × 10−3 M, 5.90 × 10−6 M, and 1.38 × 10−7 M (signal-to-noise ratio = 3). Furthermore, we used the wearable diaper sensor to monitor biomolecules at the diagnostic threshold, facilitating non-invasive diagnosis and medical monitoring of disease-related biomarkers. [Display omitted] • Noninvasive plasmonic sensor for multiplex biomarkers determination in urine developed. • The raspberry-shaped Au substrate increases uniformity and stability. • The sensor exhibits high sensitivity in the detection of urea, creatinine, and bilirubin. • A hand-held Raman spectrometer for simple SERS urinalysis. [ABSTRACT FROM AUTHOR]