Multiplexed microRNA Expression Profiling by Combined Asymmetric PCR and Label-Free Detection using Silicon Photonic Sensor Arrays

Multiplexed cytokine profiling identifies diagnostic signatures for latent tuberculosis and reactivation risk stratification

Active tuberculosis (TB) is caused by Mycobacterium tuberculosis (Mtb) bacteria and is characterized by multiple phases of infection, leading to difficulty in diagnosing and treating infected individuals. Patients with latent tuberculosis infection (LTBI) can reactivate to the active phase of infection following perturbation of the dynamic bacterial and immunological equilibrium, which can potentially lead to further Mtb transmission. However, current diagnostics often lack specificity for LTBI and do not inform on TB reactivation risk. We hypothesized that immune profiling readily available QuantiFERON-TB Gold Plus (QFT) plasma supernatant samples could improve LTBI diagnostics and infer risk of TB reactivation. We applied a whispering gallery mode, silicon photonic microring resonator biosensor platform to simultaneously quantify thirteen host proteins in QFT-stimulated plasma samples. Using machine learning algorithms, the biomarker concentrations were used to classify patients into relevant clinical bins for LTBI diagnosis or TB reactivation risk based on clinical evaluation at the time of sample collection. We report accuracies of over 90% for stratifying LTBI + from LTBI- patients and accuracies reaching over 80% for classifying LTBI + patients as being at high or low risk of reactivation. Our results suggest a strong reliance on a subset of biomarkers from the multiplexed assay, specifically IP-10 for LTBI classification and IL-10 and IL-2 for TB reactivation risk assessment. Taken together, this work introduces a 45-minute, multiplexed biomarker assay into the current TB diagnostic workflow and provides a single method capable of classifying patients by LTBI status and TB reactivation risk, which has the potential to improve diagnostic evaluations, personalize treatment and management plans, and optimize targeted preventive strategies in Mtb infections.

Nanoporous Graphene Integrated onto Bimodal Waveguide Biosensors for Detection of C-Reactive Protein

Despite the outstanding progress in photonic sensor devices, a major limitation for its application as label-free biosensors for biomedical analysis lies in the surface biofunctionalization step, that is, the reliable immobilization of the biorecognition element onto the sensor surface. Here, we report the integration of bottom-up synthesized nanoporous graphene onto bimodal waveguide interferometric biosensors as an atomically precise biofunctionalization scaffold. This combination leverages the high sensitivity of bimodal waveguide interferometers and the large functional surface area of nanoporous graphene to create highly sensitive, selective, and robust biosensors for the direct immunoassay detection of C-reactive protein (CRP), an inflammatory biomarker widely used in the clinical diagnosis of infections and sepsis. The limit of detection was determined at 3 ng/mL, which is well below the clinical cutoff levels required for the diagnostic detection of CRP in patient samples. This innovative approach holds promise for transforming diagnostics, environmental monitoring, and various fields requiring precise biomolecular detection.

Ferritin-Enhanced Direct MicroRNA Detection via Controlled Radical Polymerization

Accurate quantitative detection of tracing nucleic acids remains a great challenge in cancer genetic testing. It is crucial to propose a low-cost and highly sensitive direct gene detection method for cancer prevention and treatment. Herein, this work reports an ultrasensitive biosensor via a ferritin-enhanced atom-transfer radical polymerization (Ft-ATRP) process. Intriguingly, microRNA-21, an early marker of lung cancer, can be detected without being transcribed in advance by an innovative signal amplification strategy using ferritin-mediated aggregation of hydrophilic nitroxide radical monomers as an electrochemical biosensor. The sensor uses peptide nucleic acid probes modified on a gold electrode to accurately bind the target lung cancer marker in the sample, and then ferritin, which is naturally present in human blood, induces Ft-ATRP on the electrode surface under mild conditions. Many of 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical (MATMP) monomers with electrochemical signals are combined into polymeric chains to be modified on target assays. The limit of detection (LOD) of microRNA-21 is as low as 6.03 fM, and the detection concentration ranges from 0.01 to 100 pM (R² = 0.994). The RNA biosensor can realize great performance analysis of complicated samples in simple operation, in addition, the detection process used by the catalyst, polymers containing electrochemical signals, and the electrolyte solution all have good water solubility. The superior performance of the RNA biosensor demonstrates its potential to screen and identify lung cancer in target patients.

Biofunctionalization of Multiplexed Silicon Photonic Biosensors

Silicon photonic (SiP) sensors offer a promising platform for robust and low-cost decentralized diagnostics due to their high scalability, low limit of detection, and ability to integrate multiple sensors for multiplexed analyte detection. Their CMOS-compatible fabrication enables chip-scale miniaturization, high scalability, and low-cost mass production. Sensitive, specific detection with silicon photonic sensors is afforded through biofunctionalization of the sensor surface; consequently, this functionalization chemistry is inextricably linked to sensor performance. In this review, we first highlight the biofunctionalization needs for SiP biosensors, including sensitivity, specificity, cost, shelf-stability, and replicability and establish a set of performance criteria. We then benchmark biofunctionalization strategies for SiP biosensors against these criteria, organizing the review around three key aspects: bioreceptor selection, immobilization strategies, and patterning techniques. First, we evaluate bioreceptors, including antibodies, aptamers, nucleic acid probes, molecularly imprinted polymers, peptides, glycans, and lectins. We then compare adsorption, bioaffinity, and covalent chemistries for immobilizing bioreceptors on SiP surfaces. Finally, we compare biopatterning techniques for spatially controlling and multiplexing the biofunctionalization of SiP sensors, including microcontact printing, pin- and pipette-based spotting, microfluidic patterning in channels, inkjet printing, and microfluidic probes.

One-Step and Real-Time Detection of microRNA-21 in Human Samples for Lung Cancer Biosensing Diagnosis

The rapid diagnosis of cancer, especially in its early stages, is crucial for on-time medical treatment and for increasing the patient survival rate. Lung cancer shows the highest mortality rate and the lowest 5-year survival rate due to the late diagnosis in advanced cancer stages. Providing rapid and reliable diagnostic tools is a top priority to address the problem of a delayed cancer diagnosis. We introduce a nanophotonic biosensor for the direct and real-time detection in human plasma of the microRNA-21-5p biomarker related to lung cancer. The biosensor employs a silicon photonic bimodal interferometric waveguide that provides a highly sensitive detection in a label-free format. We demonstrate a very competitive detectability for direct microRNA-21-5p biomarker assays in human plasma samples (estimated LOD: 25 pM). The diagnostic capability of our biosensor was validated by analyzing 40 clinical samples from healthy individuals and lung cancer patients, previously analyzed by reverse-transcription quantitative polymerase chain reaction (qRT-PCR). We could successfully identify and quantify the levels of microRNA in a one-step assay, without the need for DNA extraction or amplification steps. The study confirmed the significance of implementing this biosensor technique compared to the benchmarking molecular analysis and showed excellent agreement with previous results employing the traditional qRT-PCR. This work opens new possibilities for the true implementation of point-of-care biosensors that enable fast, simple, and efficient early diagnosis of cancer diseases.

Biosensors for circulating tumor cells (CTCs)-biomarker detection in lung and prostate cancer: Trends and prospects

Cancer is one of the leading cause of death worldwide. Lung cancer (LCa) and prostate cancer (PCa) are the two most common ones particularly among men with about 20% of aggressive metastatic form leading to shorter overall survival. In recent years, circulating tumor cells (CTCs) have been investigated extensively for their role in metastatic progression and their involvement in reduced overall survival and treatment responses. Analysis of these cells and their associated biomarkers as "liquid biopsy" can provide valuable real-time information regarding the disease state and can be a potential avenue for early-stage detection and possible selection of personalized treatments. This review focuses on the role of CTCs and their associated biomarkers in lung and prostate cancer, as well as the shortcomings of conventional methods for their isolation and analysis. To overcome these drawbacks, biosensors are an elegant alternative because they are capable of providing valuable multiplexed information in real-time and analyzing biomarkers at lower concentrations. A comparative analysis of different transducing elements specific for the analysis of cancer cell and cancer biomarkers have been compiled in this review.

On-Chip Optical Detection of Viruses: A Review

The current outbreak of the coronavirus disease-19 (COVID-19) pandemic worldwide has caused millions of fatalities and imposed a severe impact on our daily lives. Thus, the global healthcare system urgently calls for rapid, affordable, and reliable detection toolkits. Although the gold-standard nucleic acid amplification tests have been widely accepted and utilized, they are time-consuming and labor-intensive, which exceedingly hinder the mass detection in low-income populations, especially in developing countries. Recently, due to the blooming development of photonics, various optical chips have been developed to detect single viruses with the advantages of fast, label-free, affordable, and point of care deployment. Herein, optical approaches especially in three perspectives, e.g., flow-free optical methods, optofluidics, and surface-modification-assisted approaches, are summarized. The future development of on-chip optical-detection methods in the wave of emerging new ideas in nanophotonics is also briefly discussed.

Advanced Evanescent-Wave Optical Biosensors for the Detection of Nucleic Acids: An Analytic Perspective

Evanescent-wave optical biosensors have become an attractive alternative for the screening of nucleic acids in the clinical context. They possess highly sensitive transducers able to perform detection of a wide range of nucleic acid-based biomarkers without the need of any label or marker. These optical biosensor platforms are very versatile, allowing the incorporation of an almost limitless range of biorecognition probes precisely and robustly adhered to the sensor surface by covalent surface chemistry approaches. In addition, their application can be further enhanced by their combination with different processes, thanks to their integration with complex and automated microfluidic systems, facilitating the development of multiplexed and user-friendly platforms. The objective of this work is to provide a comprehensive synopsis of cutting-edge analytical strategies based on these label-free optical biosensors able to deal with the drawbacks related to DNA and RNA detection, from single point mutations assays and epigenetic alterations, to bacterial infections. Several plasmonic and silicon photonic-based biosensors are described together with their most recent applications in this area. We also identify and analyse the main challenges faced when attempting to harness this technology and how several innovative approaches introduced in the last years manage those issues, including the use of new biorecognition probes, surface functionalization approaches, signal amplification and enhancement strategies, as well as, sophisticated microfluidic solutions.

Recent advances in environmental and clinical analysis using microring resonator-based sensors

Progress in the development of biosensors has dramatically improved analytical techniques. Biosensors have advantages over more conventional analytical techniques arising from attributes such as straightforward analyses, higher throughput, miniaturization, smaller sample input, and lower cost. Microring optical resonators have emerged in the area of optical sensors as an exceptional choice due to their sensitivity, ease of fabrication, multiplexity capability and label-free detection. In this paper, the sensing principle of these sensors is described. In addition, we summarize and highlight their most recent and relevant applications in environmental and clinical detection analysis.

Ultrasensitive electrochemical detection of miRNA based on DNA strand displacement polymerization and Ca2+-dependent DNAzyme cleavage

An ultrasensitive electrochemical sensing strategy for the detection of miRNA is developed combining strand displacement polymerization and a DNAzyme-catalyzed cleavage reaction.