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Tumor-derived extracellular vesicles (EVs) hold the potential to substantially improve noninvasive early diagnosis of cancer. However, analysis of nanosized EVs in blood samples has been hampered by lack of effective, rapid, and standardized methods for isolating and detecting EVs. To address this difficulty, here we use the electric-hydraulic analogy to design cascaded microfluidic circuits for pulsatile filtration of EVs via integration of a cell-removal circuit and an EV-isolation circuit. The microfluidic device is solely driven by a pneumatic clock pulse generator, allowing for preprogrammed, clog-free, gentle, high-yield, and high-purity isolation of EVs directly from blood within 30 minutes. We demonstrate its clinical utility by detecting protein markers of isolated EVs from patient blood using a polyethylene glycol–enhanced thermophoretic aptasensor, with 91% accuracy for diagnosis of early-stage breast cancer. The cascaded microfluidic circuits can have broad applications in the field of EV research.

Circulating extracellular vesicles (EVs) have emerged as a valuable source of cancer biomarkers. However, the high degree of EV heterogeneity and the complexity of clinical samples pose a challenge in the sensitive identification of tumor-derived EVs. Here we introduce a one-step thermophoretic AND gate operation (Tango) assay that integrates polyethylene glycol (PEG)-enhanced thermophoretic accumulation of EVs and simultaneous AND gate operation on EV membranes by dual-aptamers recognition. By using the Tango assay to detect tumor-derived EVs with co-presence of EpCAM and PSMA directly from serum in a homogeneous, separation-free format, we can discriminate prostate cancer (PCa) patients from benign prostatic hyperplasia (BPH) patients in the diagnostic gray zone with an accuracy of 91 % in 15 min. Our approach streamlines EV enrichment and AND gate operation on EVs in a single assay, providing a rapid, straightforward, and powerful method for precise and non-invasive diagnosis of cancer.

Infectious diseases have become a severe global public health problem. Timely and accurate diagnosis of infected individuals is the key step to control the spread of infectious diseases. Nanosensors that combine the advantages of nanomaterials and biosensing technology have been utilized for sensitive, selective, and rapid disease diagnosis and gained great attention within the chemistry, biology, and medical communities. This review presents a broad overview of a wide range of nanosensors for diagnosis of infectious diseases using different methodologies. We also outline point-of-care nanosensing methods and discuss their use in pathogen detection. This review concludes with challenges and opportunities for diagnosis of infectious diseases using nanosensors.

Both clenbuterol (CLB) and ractopamine (RAC) are β-adrenergic agonists. After long-term excessive intake, there will be adverse reactions such as headache, chest tightness, limb numbness, and serious life-threatening. Simultaneous detection of CLB and RAC in related samples is of great importance for human health. In this work, we outline a microfluidics-based indirect competitive immunoassay (MICI) system that can sensitively detect residual CLB and RAC in pork, swine blood and swine urine. The rapid detection of multiple samples can be achieved in one chip, which greatly improves the detection efficiency. This method has good stability and reproducibility and the microfluidic chips are easy to manufacture. The linear ranges for CLB and RAC detection by MICI are 0.1–2.5 ng/mL and 0.1–5 ng/mL, and the limits of detection (LODs) are 0.094 ng/mL and 0.091 ng/mL, respectively. This straightforward and portable immunoassay system provides a good platform for rapid detection of harmful substances in food samples.

The accurate detection of biological systems containing biomolecules and bioparticles is increasingly important in diverse research fields, particularly in analytical and biological chemistry. Implementing thermophoresis in microfluidic devices (thermomicrofluidics) enables the manipulation and measurement of biomolecules and bioparticles in a label‐free and high‐precision manner, providing a promising avenue for biosensing. This review presents fundamentals of thermophoresis and its coupling with other thermal‐induced physical phenomena in the microfluidic setups. We overview the capabilities of thermomicrofluidics for diverse biosensing applications such as monitoring of biomolecular interactions, detection of nucleic acids, profiling of extracellular vesicles, and manipulation of cells. Biosensing by thermomicrofluidics provides insights into physiopathological processes and disease diagnostics. Current challenges and further directions of thermomicrofluidic detection are discussed.

Rapid and sensitive identification of viral pathogens such as SARS-CoV-2 is a critical step to control the pandemic disease. Viral antigen detection can compete with gold-standard PCR-based nucleic acid diagnostics in terms of better reflection of viral infectivity and reduced risk of contamination from enzymatic amplification. Here, we report the development of a one-step thermophoretic assay using an aptamer and polyethylene glycol (PEG) for direct quantitative detection of viral particles. The assay relies on aptamer binding to the spike protein of SARS-CoV-2 and simultaneous accumulation of aptamer-bound viral particles in laser-induced gradients of temperature and PEG concentration. Using a pseudotyped lentivirus model, a limit of detection of ∼170 particles μL-1 (26 fM of the spike protein) is achieved in 15 min without the need of any pretreatment. As a proof of concept, the one-step thermophoretic assay is used to detect synthetic samples by spiking viral particles into oropharyngeal swabs with an accuracy of 100%. The simplicity, speed, and cost-effectiveness of this thermophoretic assay may expand the diagnostic tools for viral pathogens.

Molecular profiling of circulating extracellular vesicles (EVs) provides a promising noninvasive means to diagnose, monitor, and predict the course of metastatic breast cancer (MBC). However, the analysis of EV protein markers has been confounded by the presence of soluble protein counterparts in peripheral blood. Here we use a rapid, sensitive, and low-cost thermophoretic aptasensor (TAS) to profile cancer-associated protein profiles of plasma EVs without the interference of soluble proteins. We show that the EV signature (a weighted sum of eight EV protein markers) has a high accuracy (91.1 %) for discrimination of MBC, non-metastatic breast cancer (NMBC), and healthy donors (HD). For MBC patients undergoing therapies, the EV signature can accurately monitor the treatment response across the training, validation, and prospective cohorts, and serve as an independent prognostic factor for progression free survival in MBC patients. Together, this work highlights the potential clinical utility of EVs in management of MBC., A thermophoretic aptasensor can be used to profile cancer-associated proteins of extracellular vesicles (EVs) in patients’ plasma. Here, the authors use this technique to develop an EV-signature able to discriminate metastatic breast cancer, monitor treatment response, and predict patients’ progression-free survival.

Metastasis is the leading cause of epithelial cancer-associated mortality. The shedding of tumor cells into the circulatory system is a key step for metastasis. Circulating tumor cells (CTCs) are reliable biomarkers for cancer diagnostics and treatment. To obtain clinical information, accurate approaches for separating and analyzing CTCs are necessary. Microfluidic technologies have demonstrated their extraordinary abilities for separating and analyzing CTCs. In this paper, we present a comprehensive review of microfluidics-based approaches for CTCs separation and analysis. We first present the general methods for CTCs separation using the microfluidic chips, including physical properties-based approaches for CTCs enrichment and affinity-based approaches for CTCs capture, and compare the pros and cons of different separation technologies. Then we introduce microfluidics-based CTCs analysis on cellular and molecular levels and the biomedical applications of CTCs analysis. Finally, we summarize the development of microfluidics-based CTCs separation and analysis, and make a prospective of future research.

Molecular profiling of tumor-derived extracellular vesicles (tEVs) holds great promise for non-invasive cancer diagnosis. However, sensitive and accurate identification of tEVs is challenged by the heterogeneity of EV phenotypes which reflect different cell origins. Here we present a DNA computation device mediated by thermophoresis for detection of tEVs. The strategy leverages the aptamer-based logic gate using multiple protein biomarkers on single EVs as the input and thermophoretic accumulation to amplify the output signals for highly sensitive and specific profiling of tEVs. Employing this platform, we demonstrate a high accuracy of 97% for discrimination of breast cancer (BC) patients and healthy donors in a clinical cohort (n = 30). Furthermore, molecular phenotyping assessed by tEVs is in concordance with the results from tissue biopsy in BC patients. The thermophoresis-mediated molecular computation on EVs thus provides new opportunities for accurate detection and classification of cancers.

We discovered two antibacterial bimetallic nanoparticles (AuRh and AuRu NPs), that possess antibacterial activities against multi-drug resistant (MDR) Gram-negative bacteria and can cure wound infections. None of the nanoparticles comprising just one of these metals elements shows any antibiotic activities.

The outbreak of virus-induced infectious diseases poses a global public-health challenge. Nucleic acid amplification testing (NAAT) enables early detection of pandemic viruses and plays a vital role in preventing onward transmission. However, the requirement of skilled operators, expensive instrumentation, and biosafety laboratories has hindered the use of NAAT for screening and diagnosis of suspected patients. Here we report development of a fully automated centrifugal microfluidic system with sample-in-answer-out capability for sensitive, specific, and rapid viral nucleic acid testing. The release of nucleic acids and the subsequent reverse transcription loop-mediated isothermal amplification (RT-LAMP) were integrated into the reaction units of a microfluidic disc. The whole processing steps such as injection of reagents, fluid actuation by rotation, heating and temperature control, and detection of fluorescence signals were carried out automatically by a customized instrument. We validate the centrifugal microfluidic system using oropharyngeal swab samples spiked with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) armored RNA particles. The estimated limit of detection for armored RNA particles is 2 copies per reaction, the throughput is 21 reactions per disc, and the assay sample-to-answer time is approximately 70 min. This enclosed and automated microfluidic system efficiently avoids viral contamination of aerosol, and can be readily adapted for virus detection outside the diagnostic laboratory. Electronic Supplementary Material Supplementary material is available for this article at 10.1007/s11426-020-9800-6 and is accessible for authorized users.

Nucleic acids are natural biopolymers of nucleotides that store, encode, transmit and express genetic information, which play central roles in diverse cellular events and diseases in living things. The analysis of nucleic acids and nucleic acids-based analysis have been widely applied in biological studies, clinical diagnosis, environmental analysis, food safety and forensic analysis. During the past decades, the field of nucleic acids analysis has been rapidly advancing with many technological breakthroughs. In this review, we focus on the methods developed for analyzing nucleic acids, nucleic acids-based analysis, device for nucleic acids analysis, and applications of nucleic acids analysis. The representative strategies for the development of new nucleic acids analysis in this field are summarized, and key advantages and possible limitations are discussed. Finally, a brief perspective on existing challenges and further research development is provided.

Here we describe a fluorescent microspheres-based separation and analysis that enables the isolation of circulating tumor cells (CTCs) from whole blood of patients with metastatic cancer and the identification of isolated CTCs in situ without immunostaining. This approach uses antibody-functionalized fluorescent polystyrene (PS) microspheres that can selectively bind to CTCs. The binding of CTCs and fluorescent PS microspheres leads to the formation of complexes of CTCs and fluorescent PS microspheres, thereby the CTCs are size-amplified and labeled simultaneously. A pyramidal microcavity array (PMCA) is fabricated using microfabrication technology to create a precise microfilter structure with a high aspect ratio. The PMCA filter device can effectively isolate microspheres-labeled CTCs, while allow hematologic cells to deform and pass through. Using this approach, CTCs are isolated and identified in 15 of 18 patients with metastatic colorectal cancer. This approach will open new possibilities for CTCs isolation and identification and can serve a versatile platform to facilitate CTCs analysis in diverse biomedical applications.

Exosomal microRNAs (miRNAs) are reliable and noninvasive biomarkers for the early diagnosis of cancer. Yet, accurate and feasible detection of exosomal miRNAs is often hampered by the low abundance of miRNAs in exosomes and the requirement for RNA extraction in large sample volumes. Here we show a thermophoretic sensor implemented with nanoflares for in situ detection of exosomal miRNAs, without resorting to either RNA extraction or target amplification. Thermophoretic accumulation of nanoflare-treated exosomes leads to an amplified fluorescence signal upon the binding of exosomal miRNAs to nanoflares, allowing for direct and quantitative measurement of exosomal miRNAs down to 0.36 fM in 0.5 μL serum samples. One of the best markers, exosomal miR-375, showed an accuracy of 85% for detection of estrogen receptor-positive breast cancer at early stages (stages I, II). This work provides a feasible tool to improve the diagnosis of cancer.

A new composite material positioning a liquid metal core within a zeolitic imidazolate framework shell is developed. The core–shell interactions along with the structure/properties of the composite material can be easily regulated by the ligand/metal ion ratio. Enhanced photothermal conversion of the liquid metal core is achieved after ZIF-8 encapsulation.

Immunoassays whose readouts rely on chemiluminescence are increasingly useful for a broad range of analytical applications, but they are rarely made into point-of-care (POC) format because of the complex reagents required (some reagents have to be stored in low temperatures, and some reagents have to be freshly made right before the assay). This study reports a self-contained chemiluminescent lateral flow assay (CLFA), which prestores all necessary reagents. This CLFA contains three parts: the normal lateral flow assay (LFA) strip, the chemiluminescence substrate pad, and the polycarbonate (PC) holder. On the LFA strip, we simultaneously labeled horseradish peroxidase (HRP) and antibody on the gold nanoparticles (AuNPs) for the conjugate pad. For the substrate pad, we used sodium perborate as the oxidant and lyophilized the chemiluminescence substrate on the glass fiber, which allows long-term storage. After the transfer of substrate from the substrate pad to the nitrocellulose (NC) membrane, we captured the chemiluminescence signal for the quantification of the targets. The HRP on the AuNPs can amplify the chemiluminescence signal efficiently. We used this CLFA system to detect both macromolecules and small molecules successfully. This self-contained and easily processable device is exceedingly appropriate for rapid detection and is a convenient platform for POC testing.

In this study, we developed a microfluidic chip integrated with on-chip valves for quantitative detection of biomarkers. The sandwich-structured microfluidic chip consists of a top fluidic layer embedded with a zigzag channel, a middle tinfoil layer pre-patterned with protein stripes, and a bottom substrate layer with two waste chambers. A set of customized on-chip valves was introduced for precise control of fluid flow. To improve the production volume and uniformity among chips, we selected an injection molding method for mass-production of the main components. We standardized the process of sealing chip layers and assembling the valve holder to improve the effectiveness of cooperation with the instrument. To demonstrate the versatility of the microfluidic chip for quantitative detection of biomarkers, we used it to automatically detect C-reactive proteins (CRP), interleukin-6 (IL-6), insulin, and osteocalcin with high sensitivity and excellent reproducibility inside a customized and portable instrument. We further conducted the automated chip-based chemiluminescence immunoassay to test CRP in serum samples for demonstration of potential clinical applications, assess the activity of capture antibodies of CRP (CRP-Ab1) on the tinfoil layer for preliminary assessment of storage stability, and simultaneously detect CRP and IL-6 for confirmation of scalable multiplexation. This microfluidic chip for quantitative, automated, and portable immunoassay provides a promising choice for clinical practices.

The analysis of messenger RNA (mRNA) in extracellular vesicles (EVs) may provide unprecedented opportunities for non-invasive and rapid diagnosis of cancers. However, clinical utility of EV mRNA is often hampered by the extremely low abundance of mRNA in EVs and the complicated procedures for mRNA detection. Here we address these challenges by developing an ultrasensitive assay for in situ measurement of EV mRNA, which combines FRET-based DNA tetrahedron (FDT) for efficient EV internalization and target mRNA detection, and size-selective thermophoretic accumulation for amplification of FRET signal in EVs. This DNA tetrahedron-based thermophoretic assay (DTTA) achieves a limit of detection (LoD) of 14 aM for detecting PSA mRNA in serum EVs, with resorting to RNA extraction and enzyme amplification. The DTTA showed that EV PSA mRNA outperforms serum PSA protein, the gold standard in PCa screening, for discrimination between prostate cancer and benign prostatic hyperplasia (area under the curve: 0.93 versus 0.74; 42 patients). This technology may greatly expand the applications of DNA nanostructure-enabled liquid biopsy.

Microfluidic platforms capable of automated, rapid, sensitive, and quantitative detection of biomarkers from patient samples could make a major impact on clinical or point-of-care (POC) diagnosis. In this work, we realize an automated diagnostic platform composed of two main components: (1) a disposable, self-contained, and integrated microfluidic chip and (2) a portable instrument that carries out completely automated operations. To demonstrate its potential for real-world application, we use injection molding for mass fabrication of the main components of disposable microfluidic chips. The assembled three-layered chip with on-chip mechanical valves for fluid control consists of (1) a top silicone fluidic layer with embedded zigzag microchannels, reagent reservoirs and a negative pressure port, (2) a middle tinfoil layer with patterned antibody/antigen stripes, and (3) a bottom silicone substrate layer with waste reservoirs. The versatility of the microfluidics-based system is demonstrated by implementation of a chemiluminescence immunoassay for quantitative detection of C-reactive protein (CRP) and testosterone in real clinical samples. This lab-on-a-chip platform with features of quantitation, portability and automation provides a promising strategy for POC diagnosis.

Microfluidics, which enables manipulation of minute amount of fluids with nano-/micro-structures, has been applied in biomedical applications over past decades. This chapter will introduce several representative advancements in using microfluidics for cell manipulation and biochemical analysis.

The electrochemical applications of traditional carbon nanomaterials such as carbon nanotubes (CNTs) and graphene (G) powders are significantly impeded by their poor three-dimensional (3D) conductivity and lack of hierarchical porous structure. Here, we have constructed a 3D highly conductive CNTs networks and further combined it with mesoporous carbon (mC) for the creation of a core-shell structured (CNT@mC) composite sponge that featured 3D conductivity and hierarchical porous structure. In the composite sponge, interconnected CNTs efficiently eliminates the contact resistance and the hierarchical pores significantly facilitate the mass transport. The electron transfer rates, electroactive surface area and catalytic activity of the CNT@mC composite sponge based catalysts were tested in the direct methanol fuel cells (DMFCs) and electrochemical sensors. In DMFCs, the Pd nanoparticles deposited CNT@mC showed significantly improved catalytic activity and methanol oxidization current. As for amperometric sensing of endocrine disrupting compounds (EDCs), CNT@mC-based catalyst gave a liner range from 10 nM to 1 mM for bisphenol A (BPA) detection and showed great promise for simultaneous detection of multiple EDCs. BPA recovery from environmental water further indicated the potential practical applications of the sensor for BPA detection. Finally, the electrochemical performance of CNT@mC were also investigated in impedimetric sensors. Good selectivity was obtained in impedimetric sensing of BPA and the detection limit was measured to be 0.3 nM. This study highlighted the exceptional electrochemical properties of the CNT@mC composite sponge enabled by its 3D conductivity and hierarchical porous structure. The strategy described may further pave a way for the creation of novel functional materials through integrating multiple superior properties into a single nanostructure for future clean energy technologies and environmental monitoring systems.

The rapid development of microfluidics technology has promoted new innovations in materials science, particularly by interacting with biological systems, based on precise manipulation of fluids and cells within microscale confinements. This article reviews the latest advances in microfluidics-based biomaterials and biodevices, highlighting some burgeoning areas such as functional biomaterials, cell manipulations, and flexible biodevices. These areas are interconnected not only in their basic principles, in that they all employ microfluidics to control the makeup and morphology of materials, but also unify at the ultimate goals in human healthcare. The challenges and future development trends in biological application are also presented.