Machine Learning-Assisted Janus Colorimetric Face Mask for Breath Ammonia Analysis.

Artificial olfactory systems have been widely used in medical fields such as in the analysis of volatile organic compounds (VOCs) in human exhaled breath. However, there is still an urgent demand for a portable, accurate breath VOC analysis system for the healthcare industry. In this work, we proposed a Janus colorimetric face mask (JCFM) for the comfortable evaluation of breath ammonia levels by combining the machine learning K-nearest neighbor (K-NN) algorithm. Such a Janus fabric is designed for the unidirectional penetration of exhaled moisture, which can reduce stickiness and ensure facial dryness and comfort. Four different pH indicators on the colorimetric array serve as recognition elements that cross-react with ammonia, capturing the optical fingerprint information on breath ammonia by mimicking the sophisticated olfactory structure of mammals. The Euclidean distance (ED) is used to quantitatively describe the ammonia concentration between 1 ppm and 10 ppm, indicating that there is a linear relationship between the ammonia concentration and the ED response (R2 = 0.988). The K-NN algorithm based on RGB response features aids in the analysis of the target ammonia level and achieves a prediction accuracy of 96%. This study integrates colorimetry, Janus design, and machine learning to present a wearable and portable sensing system for breath ammonia analysis.

Wearable Vertical Graphene-Based Microneedle Biosensor for Real-Time Ketogenic Diet Management.

Ketogenic diets have attracted substantial interest in the treatment of chronic diseases, but there are health risks with long-term regimes. Despite the advancements in diagnostic and therapeutic methods in modern medicine, there is a huge gap in personalized health management of this dietary strategy. Hence, we present a wearable microneedle biosensor for real-time ketone and glucose monitoring. The microneedle array possesses excellent mechanical properties, allowing for consistent sampling of interstitial biomarkers while reducing the pain associated with skin puncture. Vertical graphene with outstanding electrical conductivity provides the resulting sensor with a high sensitivity of 234.18 µA mM-1 cm-2 and a low limit detection of 1.21 µM. When this fully integrated biosensor was used in human volunteers, it displayed an attractive analytical capability for tracking the dynamic metabolite levels. Moreover, the results of the on-body evaluation established a significant correlation with commercial blood measurements. Overall, this cost-effective and efficient sensing platform can accelerate the application of a ketogenic diet in personal nutrition and wellness management.

Two-Dimensional Nickel Porphyrinic Metal-Organic Framework-Modified Electrode for Electrochemical Sensing.

Due to their highly exposed active sites and high aspect ratio caused by their substantial lateral dimension and thin thickness, two-dimensional (2D) metal-organic framework (MOF) nanosheets are currently considered a potential hybrid material for electrochemical sensing. Herein, we present a nickel-based porphyrinic MOF nanosheet as a versatile and robust platform with an enhanced electrochemical detection performance. It is important to note that the nickel porphyrin ligand reacted with Cu(NO3)2·3H2O in a solvothermal process, with polyvinylpyrrolidone (PVP) acting as the surfactant to control the anisotropic development of creating a 2D Cu-TCPP(Ni) MOF nanosheet structure. To realize the exceptional selectivity, sensitivity, and stability of the synthesized 2D Cu-TCPP(Ni) MOF nanosheet, a laser-induced graphene electrode was modified with the MOF nanosheet and employed as a sensor for the detection of p-nitrophenol (p-NP). With a detection range of 0.5-200 µM for differential pulse voltammetry (DPV) and 0.9-300 µM for cyclic voltammetry (CV), the proposed sensor demonstrated enhanced electrochemical performance, with the limit of detection (LOD) for DPV and CV as 0.1 and 0.3 µM, respectively. The outstanding outcome of the sensor is attributed to the 2D Cu-TCPP(Ni) MOF nanosheet's substantial active surface area, innate catalytic activity, and superior adsorption capacity. Furthermore, it is anticipated that the proposed electrode sensor will make it possible to create high-performance electrochemical sensors for environmental point-of-care testing since it successfully detected p-NP in real sample analysis.

Design and application of dual-emission metal-organic framework-based ratiometric fluorescence sensors.

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.

Oriented Antibody-Assembled Metal-Organic Frameworks for Persistent Wearable Sweat Cortisol Detection.

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 (Cmab) 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.

Fully Integrated Ratiometric Fluorescence Enrichment Platform for High-Sensitivity POC Testing of Salivary Cancer Biomarkers.

The point-of-care (POC) testing of cancer biomarkers in saliva with both high sensitivity and accuracy remains a serious challenge in modern clinical medicine. Herein, we develop a new fully integrated ratiometric fluorescence enrichment platform that utilizes acoustic radiation forces to enrich dual-emission sandwich immune complexes for a POC visual assay. As a result, the color signals from red and green fluorescence (capture probe and report probe, respectively) are enhanced by nearly 10 times, and colorimetric sensitivity is effectively improved. When illuminated using a portable UV lamp, the fluorescence color changing from red to green can be clearly seen with the naked eye, which allows a semiqualitative assessment of the carcinoembryonic antigen (CEA) level. In combination with a homemade smartphone-based portable device, cancer biomarkers like CEA are quantified, achieving a limit of detection as low as 0.012 ng/mL. We also directly quantify CEA in human saliva samples to investigate the reliability of this fully integrated platform, thus validating the usefulness of the proposed strategy for clinical diagnosis and home monitoring of physical conditions.

Active Enrichment of Nanoparticles for Ultra-Trace Point-of-Care COVID-19 Detection.

Active enrichment can detect nucleic acid at ultra-low concentrations without relatively time-consuming polymerase chain reaction (PCR), which is an important development direction for future rapid nucleic acid detection. Here, we reported an integrated active enrichment platform for direct hand-held detection of nucleic acid of COVID-19 in nanoliter samples without PCR. The platform consists of a capillary-assisted liquid-carrying system for sampling, integrated circuit system for ultrasound output, and cell-phone-based surface-enhanced Raman scattering (SERS) system. Considering the acoustic responsiveness and SERS-enhanced performance, gold nanorods were selected for biomedical applications. Functionalized gold nanorods can effectively capture and enrich biomarkers under ultrasonic aggregation. Such approaches can actively assemble gold nanorods in 1-2 s and achieved highly sensitive (6.15 × 10-13 M) SERS detection of COVID-19 biomarkers in nanoliter (10-7 L) samples within 5 min. We further demonstrated the high stability, repeatability, and selectivity of the platform, and validated its potential for the detection of throat swab samples. This simple, portable, and ultra-trace integrated active enrichment detection platform is a promising diagnostic tool for the direct and rapid detection of COVID-19.

Signal differentiation models for multiple microRNA detection: a critical review.

MicroRNAs (miRNAs) are a class of small, single-stranded non-coding RNAs which have critical functions in various biological processes. Increasing evidence suggested that abnormal miRNA expression was closely related to many human diseases, and they are projected to be very promising biomarkers for non-invasive diagnosis. Multiplex detection of aberrant miRNAs has great advantages including improved detection efficiency and enhanced diagnostic precision. Traditional miRNA detection methods do not meet the requirements of high sensitivity or multiplexing. Some new techniques have opened novel paths to solve analytical challenges of multiple miRNA detection. Herein, we give a critical overview of the current multiplex strategies for the simultaneous detection of miRNAs from the perspective of two different signal differentiation models, including label differentiation and space differentiation. Meanwhile, recent advances of signal amplification strategies integrated into multiplex miRNA methods are also discussed. We hope this review provides the reader with future perspectives on multiplex miRNA strategies in biochemical research and clinical diagnostics.

Enhanced Isothermal Amplification for Ultrafast Sensing of SARS-CoV-2 in Microdroplets.

Rapid and high-throughput screening is critical to control the COVID-19 pandemic. Recombinase polymerase amplification (RPA) with highly accessible and sensitive nucleic acid amplification has been widely used for point-of-care infection diagnosis. Here, we report an integrated microdroplet array platform composed of an ultrasonic unit and minipillar array to enhance the RPA for ultrafast, high-sensitivity, and high-throughput detection of SARS-CoV-2. On such a platform, the independent microvolume reactions on individual minipillars greatly decrease the consumption of reagents. The microstreaming driven by ultrasound creates on-demand contactless microagitation in the microdroplets and promotes the interaction between RPA components, thus greatly accelerating the amplification. In the presence of microstreaming, the detection time is 6-12 min, which is 38.8-59.3% shorter than that of controls without microstreaming, and the end-point fluorescence intensity also increased 1.3-1.7 times. Furthermore, the microagitation-enhanced RPA also exhibits a lower detection limit (0.42 copy/µL) for SARS-CoV-2 in comparison to the controls. This integrated microdroplet array detection platform is expected to meet the needs for high-throughput nucleic acid testing (NAT) to improve the containment of viral transmission during the epidemic, as well as provide a potential platform for the timely detection of other pathogens or viruses.

A Portable Electrochemical Sensor Based on Manganese Porphyrin-Functionalized Carbon Cloth for Highly Sensitive Detection of Nitroaromatics and Gaseous Phenol.

Organic pollutants (OPs) have garnered a considerable amount of attention in recent times due to their extreme toxicity toward humans and the ecosystem. The need for an inexpensive yet robust, sensitive, selective, and easy-to-operate method for detecting OPs remains a challenge. Herein, a portable electrochemical sensor is proposed based on manganese porphyrin-functionalized carbon cloth (CC). To explain the electrochemical performance of the sensor, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed. The presence of manganese(III) ion in the center of the porphyrin ligand acted as an agent for the transfer of electrons and enhanced sensitivity toward analyte-specific redox catalysis. Moreover, it allowed for the concurrent detection of multiple analytes in a complex environment. The modified CC electrode can selectively detect nitroaromatic and phenolic compounds with accessible data collected through wireless means onto a smartphone device. The as-synthesized electrode demonstrated a higher sensitivity toward the detection of nitrobenzene (NB) and aqueous phenol with a limit of detection (LOD) found to be 5.9268 × 10-10 M and 4.0178 × 10-10 M, respectively. Additionally, our proposed portable electrochemical sensor demonstrates a high selectivity and reproducibility toward nitroaromatic and phenolic compounds, which can be employed in real complex water samples. With regard to the sensor's remarkable electrochemical performance, it is envisaged that such a sensor could pave the way for environmental point of care (POC) testing.

Powering bioanalytical applications in biomedicine with light-responsive Janus micro-/nanomotors.

Possessing both unique asymmetric structures and remote-controlled active movement, light-responsive Janus micro-/nanomotors offer the possibility of breaking through the limitations of traditional biomedicine, and have fascinated and inspired researchers. Despite many obstacles toward the clinical application, impressive progress of light-responsive Janus micro-/nanomotors for bioanalytical applications has been made over the past decades. In this review, we first briefly introduced several main light-driven Janus micro-/nanomotors, then focused on their typical bioanalytical applications such as biosensing, bioimaging, and theranostic. In the end, we summarized the remaining challenges of light-responsive Janus micro-/nanomotors in the practical application and also proposed potential solutions in the future.

Portable electrochemical micro-workstation platform for simultaneous detection of multiple Alzheimer's disease biomarkers.

Alzheimer's disease, as a most prevalent type of dementia, is quickly becoming one of the most expensive, lethal, and burdening diseases of this century. Though there are still no efficient therapies, early diagnosis and intervention are important directive significance to clinical works. Here, we develop a portable electrochemical micro-workstation platform consisting of an electrochemical micro-workstation and integrated electrochemical microarray for simultaneously detecting multiple AD biomarkers including Aß40, Aß42, T-tau, and P-tau181 in serum. The integrated electrochemical microarray is mainly used for droplet sample manipulation and signal generation. The micro-workstation can regulate signals and transfer the signals to a smartphone by Bluetooth embedded inside. This portable electrochemical micro-workstation platform exhibits excellent analysis performance. The LODs for Aß40, Aß42, T-tau, and P-tau181 are 0.125 pg/mL, 0.089 pg/mL, 0.142 pg/mL, and 0.176 pg/mL, respectively, which satisfies the needs of detecting AD biomarkers in serum. The combination of portable micro-workstation and integrated electrochemical microarray provides a promising strategy for the early diagnosis of Alzheimer's disease and personal healthcare.

Detection of coronavirus in environmental surveillance and risk monitoring for pandemic control.

The novel human infectious coronaviruses (CoVs) responsible for severe respiratory syndromes have raised concerns owing to the global public health emergencies they have caused repeatedly over the past two decades. However, the ongoing coronavirus disease 2019 (COVID-19) pandemic induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has received unprecedented attention internationally. Monitoring pathogenic CoVs in environmental compartments has been proposed as a promising strategy in preventing the environmental spread and tracing of infectious diseases, but a lack of reliable and efficient detection techniques is still a significant challenge. Moreover, the lack of information regarding the monitoring methodology may pose a barrier to primary researchers. Here, we provide a systematic introduction focused on the detection of CoVs in various environmental matrices, comprehensively involving methods and techniques of sampling, pretreatment, and analysis. Furthermore, the review addresses the challenges and potential improvements in virus detection techniques for environmental surveillance.

Biospired Janus Silk E-Textiles with Wet-Thermal Comfort for Highly Efficient Biofluid Monitoring.

Functionalized textiles capable of biofluid administration are favorable for enhancing the wet-thermal comfort of the wearer and healthcare performance. Herein, inspired by the Janus wettability of lotus leaf, we propose a skin-comfortable Janus electronic textile (e-textile) based on natural silk materials for managing and analysis of biofluid. Silk materials are chosen and modified as both a textile substrate and a sensing electrode due to its natural biocompatibility. The unidirectional biofluid behavior of such Janus silk substrate facilitates a comfortable skin microenvironment, including weakening the undesired wet adhesion (∼0 mN cm-2) and avoiding excessive heat or cold on the epidermis. We noninvasively analyze multiple targets of human sweat with less required liquid volume (∼5 µL) and a faster (2-3 min) response time based on the silk-based yarn electrode woven into the hydrophilic side of Janus silk. This work bridges the gap between physiological comfort and sensing technology using biomass-derived elements, presenting a new type of smart textiles for wet-thermal management and health monitoring.

Ultra-Trace Protein Detection by Integrating Lateral Flow Biosensor with Ultrasound Enrichment.

Lateral flow biosensor (LFB) is one of the most successful and applied commercial detection methods for food safety, drug abuse, and disease. Here, we integrated the ultrasound enrichment as sample preparation with LFB to achieve the ultra-trace protein detection in blood. When the ultrasound field is applied, the interaction between the acoustic field and gold nanoparticles can gather specifically modified gold nanoparticles toward pressure nodes in seconds and enrich target proteins. Such an approach can detect protein with a linear range of 1-20 ng mL-1 and detection limit of 0.58 ng mL-1 in blood within 20 min, which enormously reduces false positive readings caused by interference in real blood samples with complex components. Such a microchip that integrated acoustic enrichment with LFB shows great potential in detecting ultra-trace biomarkers for clinical diagnosis.

Customizable Textile Sensors Based on Helical Core-Spun Yarns for Seamless Smart Garments.

Most of the current sensors cannot meet the needs for seamless integration into the textile substrates of smart clothing and require improvements in terms of comfort and durability. Herein, smart textile-based sensors that have different sensing properties with integrated electronic elements were fabricated by knitting graphene-based helical conductive core-spun yarns. Such graphene-modified core-spun yarns are employed as building blocks of textile strain sensors, which showed high elasticity (ε > 300%), fast response time (120 ms), excellent reproducibility (over 10 000 cycles), wide sensing range (up to 100% strain), and low detection limit (0.3% strain). Thus, resistance-type strain sensors and capacitance-type pressure sensors composed of graphene-based smart fabric could be used to monitor large-scale limb movement and subtle human physiological signals. Such seamless smart textile-based fabric composed of superelastic helical conductive core-spun yarns shows great potential for fabricating an intelligent device to achieve real-time precise medicine and healthcare.

Integrated Ultrasonic Aggregation-Induced Enrichment with Raman Enhancement for Ultrasensitive and Rapid Biosensing.

Enrichment and enhancement are two important aspects of ultratrace biomolecule recognition in complex biological samples. Here we integrate acoustic aggregation of modified Au nanorods with Raman enhancement for all-in-one ultratrace rapid biomolecule detection in one microliter solution. Arising from the interaction between individual nanoparticles and the acoustic field, the aggregation of Au nanorods results in rapid migration of specifically modified Au nanorods toward pressure node in a few seconds and accompanies the enrichment of specific biomolecular. As a proof concept, rapid and sensitive surface-enhanced Raman scattering (SERS) detection of nucleic acids (10-13 M) in microliter-scale (10-6 L) sample is achieved. Such an approach integrates ultrasonic aggregation-induced enrichment (uAIE) with Raman enhancement, holding considerable promise for efficient, sensitive, and rapid on-chip detection of ultratrace biomarkers in a clinical sample solution.

Cancer Cell Membrane Camouflaged Semi-Yolk@Spiky-Shell Nanomotor for Enhanced Cell Adhesion and Synergistic Therapy.

Cell adhesion of nanosystems is significant for efficient cellular uptake and drug delivery in cancer therapy. Herein, a near-infrared (NIR) light-driven biomimetic nanomotor is reported to achieve the improved cell adhesion and cellular uptake for synergistic photothermal and chemotherapy of breast cancer. The nanomotor is composed of carbon@silica (C@SiO2 ) with semi-yolk@spiky-shell structure, loaded with the anticancer drug doxorubicin (DOX) and camouflaged with MCF-7 breast cancer cell membrane (i.e., mC@SiO2 @DOX). Such biomimetic mC@SiO2 @DOX nanomotors display efficient self-thermophoretic propulsion due to a thermal gradient generated by asymmetrically spatial distribution. Moreover, the MCF-7 cancer cell membrane coating can remarkably reduce the bioadhesion of nanomotors in biological medium and exhibit highly specific self-recognition of the source cell line. The combination of effective propulsion and homologous targeting dramatically improves cell adhesion and the resultant cellular uptake efficiency in vitro from 26.2% to 67.5%. Therefore, the biomimetic mC@SiO2 @DOX displays excellent synergistic photothermal and chemotherapy with over 91% MCF-7 cell growth inhibition rate. Such smart design of the fuel-free, NIR light-powered biomimetic nanomotor may pave the way for the application of self-propelled nanomotors in biomedicine.

Janus dendritic silica/carbon@Pt nanomotors with multiengines for H2O2, near-infrared light and lipase powered propulsion.

Hybrid micro/nanomotors with multiple distinct propulsion modes are expected to improve their motion ability in complex body fluids. Herein, we report a multi-stimuli propelled Janus lipase-modified dendritic silica/carbon@Pt (DMS/C@Pt) nanomotor with built-in engines for hybrid propulsions of H2O2, light, and enzyme. The enhanced motion of the DMS/C@Pt nanomotor is achieved under the stimulus of H2O2 that produces an oxygen concentration gradient derived from the asymmetric catalysis of Pt nanoparticles. Irradiated with near-infrared (NIR) light, the uneven photothermal effect of the carbon part propels this nanomotor by self-thermophoresis. Besides, lipase is efficiently loaded into the dendritic pores, which decomposes triglyceride on the silica part and induces self-diffusiophoretic propulsion. These multiple propulsions shed light on the rational integration of various functional building blocks into one micro/nanomotor for complex tasks in biomedical applications.

Construction of dendritic Janus nanomotors with H2O2 and NIR light dual-propulsion via a Pickering emulsion.

Artificial micro/nanomotors with a dual-propulsion property have attracted considerable attention recently due to their attractive performances in complex fluidic environments. In this work, we successfully constructed Janus nanomotors with H2O2 and NIR light dual-propulsion by employing dendritic porous silica nanoparticles (DPSNs) as carriers via a Pickering emulsion and electrostatic self-assembly. The aminopropyl-modified DPSNs (DPSNs-NH2) with positive charge were semiburied in paraffin wax microparticles in order to achieve electrostatic adsorption of Pt nanoparticles (NPs) with negative charge on the exposed surface for H2O2 propulsion, followed by electrostatic adsorption of negatively charged CuS NPs with excellent NIR light absorption on the other exposed surface of the eluted DPSNs-NH2@Pt for NIR light propulsion. Center-radial large mesopores facilitate the high density loading of Pt NPs and CuS NPs for efficient propulsion. Compared with the commonly used sputtering approach, this Pickering emulsion method can realize relatively large-scale fabrication of Janus NPs. DPSNs-NH2@Pt@CuS Janus nanomotors can be effectively driven not only by self-diffusiophoresis, which results from the decomposition of H2O2 catalyzed by Pt NPs, but also by self-thermophoresis, which is generated from thermal gradients caused by the photothermal effect of CuS NPs. Moreover, the motion speed of the nanomotors can be conveniently modulated by regulating the H2O2 concentration and NIR light intensity. This work provides a novel exploration into the construction of dual-propulsion nanomotors, which are supposed to have significant potential in biomedical and intelligent device applications.