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

Identification and ultrasensitive quantification of H. pylori infections on gastric and stool human samples with a photonic label-free nanobiosensor

Helicobacter pylori is a widespread bacterium that infects the stomach, causing gastric disorders associated with high morbidity and mortality worldwide. Current methods for identifying and quantifying this pathogen rely on invasive and non-invasive tests. Although combining these methods allows accurate diagnosis, they have multiple drawbacks, and there is no single reliable gold standard test. New, more sensitive strategies involving molecular techniques, such as digital PCR, have been developed but require complex and expensive instruments. Herein, we implement and validat a nanophotonic bimodal waveguide (BiMW) biosensor for the sensitive and accurate detection of H. pylori in gastric biopsies and stool. This biosensor offers real-time, label-free detection, high sensitivity, and the capability to be integrated into compact devices. By employing monoclonal antibodies targeting specific membrane proteins found in H. pylori, the biosensor enables unique recognition of the bacterium, demonstrating its potential as an alternative diagnostic tool. The BiMW biosensor provides highly accurate H. pylori quantification in under 20 min, with limits of detection (LOD) of 89 ± 35 CFU/mL for antrum gastric biopsies and 82 ± 9 CFU/mL for stool samples. Clinical validation with 40 samples (20 gastric biopsies and 20 stool samples) showed sensitivity and specificity of 90 % for gastric biopsies and 95 % for stool samples, offering diagnostic reliability equivalent to semiquantitative ELISA tests and enabling more efficient and timely detection of H. pylori infections. This test can significantly improve the speed of diagnosis and contribute to the development of more effective strategies for H. pylori eradication.

Simultaneous Detection of MMP-1 and MMP-12 Using Au-Se Nanoprobe for Advancing NSCLC Diagnosis

This study presents the development and characterization of Au-Se nanoprobes (NPs) for the specific and simultaneous detection of matrix metalloproteinase-1 and -12 (MMP-1/12), key biomarkers in non-small-cell lung cancer (NSCLC). Leveraging the stability of Au-Se bonds against biological thiols, such as glutathione (GSH), the NPs exhibit remarkable resistance to interference, maintaining its fluorescence signal across a wide range of temperatures, pH levels, and in the presence of high concentrations of GSH. The synthesized NPs demonstrate high specificity and sensitivity toward MMP-1/12 in vitro, with optimal imaging achieved after 4 h of incubation in NSCLC A549 cells. Furthermore, confocal imaging experiments successfully distinguished between NSCLC A549 cells and normal lung epithelial cells (Beas-2b), underscoring the potential of these NPs in early NSCLC diagnosis and the study of tumor microenvironments. This work not only introduces a reliable tool for cancer biomarker detection but also contributes to the advancement of nanomaterial applications in NSCLC diagnosis.

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.

PCR- and wash-free detection of serum miRNA via signaling probe hybridization

Detection of microRNAs (miRNAs) in the serum is an effective liquid biopsy technique for cancer diagnosis. However, conventional diagnostic methods are time-consuming and complex. Therefore, in this study, we established a signaling probe-based DNA microarray system for miRNA detection. PCR, fluorescence labeling, and washing are not necessary for signaling probes. Four probes were designed using different miRNAs as diagnostic cancer markers. The developed system is useful for various miRNAs, regardless of their target lengths (18-26-mer) and GC content (36%-89%). Here, all the assays were performed within 40 min. Overall, our signaling probe-based DNA hybridization system facilitates the simple and rapid detection of serum miRNAs without the need for gene amplification, fluorescence labeling and washing.

Rapid enzyme-free detection of miRNA-21 in human ovarian cancerous cells using a fluorescent nanobiosensor designed based on hairpin DNA-templated silver nanoclusters

BACKGROUND

Cancer is known as one of the main non-communicable diseases and the leading cause of death in the new era. Early diagnosis of cancer requires the identification of special biomarkers. Currently, microRNAs (miRNAs) have attracted the attention of researchers as useful biomarkers for cancer early detection. Hence, various methods have been recently developed for detecting and monitoring miRNAs. Among all miRNAs, detection of miRNA-21 (miR-21) is important because it is abnormally overexpressed in most cancers. Here, a new biosensor based on silver nanoclusters (AgNCs) is introduced for detecting miR-21.

RESULTS

As a fluorescent probe, a rationally designed hairpin sequence containing a poly-cytosine motif was used to facilitate the formation of AgNCs. A guanine-rich sequence was also employed to enhance the sensing signal. It was found that in the absence of miR-21, adding a guanine-rich sequence to the detecting probe caused only a slight change in the fluorescence emission intensity of AgNCs. While in the presence of miR-21, the emission signal enhanced. A direct correlation was observed between the increase in the fluorescence of AgNCs and the concentration of miR-21. The performance of the proposed biosensor was characterized thoroughly and confirmed. The biosensor detected miR-21 in an applicable linear range from 9 pM to 1.55 nM (LOD: 2 pM).

SIGNIFICANCE

The designed biosensor was successfully applied for detecting miR-21 in human plasma samples and also in human normal and lung and ovarian cancer cells. This biosensing strategy can be used as a model for detecting other miRNAs. The designed nanobiosensor can measure miR-21 without using any enzymes, with fewer experimental steps, and at a low cost compared to the reported biosensors in this field.

Tumor-associated exosomes in cancer progression and therapeutic targets

Exosomes are small membrane vesicles that are released by cells into the extracellular environment. Tumor-associated exosomes (TAEs) are extracellular vesicles that play a significant role in cancer progression by mediating intercellular communication and contributing to various hallmarks of cancer. These vesicles carry a cargo of proteins, lipids, nucleic acids, and other biomolecules that can be transferred to recipient cells, modifying their behavior and promoting tumor growth, angiogenesis, immune modulation, and drug resistance. Several potential therapeutic targets within the TAEs cargo have been identified, including oncogenic proteins, miRNAs, tumor-associated antigens, immune checkpoint proteins, drug resistance proteins, and tissue factor. In this review, we will systematically summarize the biogenesis, composition, and function of TAEs in cancer progression and highlight potential therapeutic targets. Considering the complexity of exosome-mediated signaling and the pleiotropic effects of exosome cargoes has challenge in developing effective therapeutic strategies. Further research is needed to fully understand the role of TAEs in cancer and to develop effective therapies that target them. In particular, the development of strategies to block TAEs release, target TAEs cargo, inhibit TAEs uptake, and modulate TAEs content could provide novel approaches to cancer treatment.

Mix-and-Read Digital MicroRNA Analysis Based on Flow Cytometric Counting of Target-Clicked Nanobead Dimer

A one-step, enzyme-free, and highly sensitive digital microRNA (miRNA) assay is rationally devised based on flow cytometric counting of target miRNA-clicked nanobead dimers via a facile mix-and-read manner. In this strategy, highly efficient miRNA-sandwiched click chemical ligation of two DNA probes may remarkably stabilize and boost the dimer formation between two kinds of fluorescence-coded nanobeads, and the number of as-produced bead dimers will be target dose-responsive, particularly when the trace number of miRNA is much less than that of employed nanobeads. Finally, each fluorescence-coded bead dimer can be easily identified and digitally counted by a powerful flow cytometer (FCM) and accordingly, the amount of target miRNA can be accurately quantified in a digital way. This new digital miRNA assay can be accomplished with a facile mix-and-read operation just by simply mixing the target miRNA with two kinds of preprepared DNA probe-functionalized nanobeads, which do not require any nucleic acid amplification, purification, and complex operation procedures. In spite of the extremely simple one-step operation, benefiting from the low-background but high target-mediated click ligation efficiency, and the powerfully digital statistical capability of FCM, this strategy achieves high sensitivity with a quite low detection limit of 5.2 fM target miRNA as well as high specificity and good generality for miRNA analysis, pioneering a new direction for fabricating digital bioassays.

Enhancing sensitivity towards electrochemical miRNA detection using an affordable paper-based strategy

In the era of liquid biopsy, microRNAs emerge as promising candidates for the early diagnosis and prognosis of cancer, offering valuable insights into the disease's development. Among all the existing analytical approaches, even if traditional approaches such as the nucleic acid amplification ones have the advantages to be highly sensitive, they cannot be used at the point-of-care, while sensors might be poorly sensitive despite their portability. In order to improve the analytical performance of existing electroanalytical systems, we demonstrate how a simple chromatographic paper-based disk might be useful to rationally improve the sensitivity, depending on the number of preconcentration cycles. A paper-based electrochemical platform for miRNA detection has been developed by modifying a paper-based electrode with a methylene blue (MB)-modified single-stranded sequence (ssDNA) complementary to the chosen miRNA, namely miR-224 that is associated with lung cancer. A detection limit of ca. 0.6 nM has been obtained in spiked human serum samples. To further enhance the sensitivity, an external chromatographic wax-patterned paper-based disk has been adopted to preconcentrate the sample, and this has been demonstrated both in standard and in serum solutions. For each solution, three miR-224 levels have been preconcentrated, obtaining a satisfactory lowering detection limit of ca. 50 pM using a simple and sustainable procedure. This approach opens wide possibilities in the field of analytical and bioanalytical chemistry, being useful not only for electrochemistry but also for other architectures of detection and transduction.

Immunotherapy in melanoma: Can we predict response to treatment with circulating biomarkers?

Melanoma is the most aggressive form of skin cancer, representing approximately 4% of all cutaneous neoplasms and accounting for up to 80% of deaths. Advanced stages of melanoma involve metastatic processes and are associated with high mortality and morbidity, mainly due to the rapid dissemination and heterogeneous responses to current therapies, including immunotherapy. Immune checkpoint inhibitors (ICIs) are currently used in the treatment of metastatic melanoma (MM) and despite being linked to an increase in patient survival, a high percentage of them still do not benefit from it. Accordingly, the number of therapeutic regimens for MM patients using ICIs either alone or in combination with other therapies has increased, together with the need for reliable biomarkers that can both predict and monitor response to ICIs. In this context, circulating biomarkers, such as DNA, RNA, proteins, and cells, have emerged due to their ability to reflect disease status. Moreover, blood tests are minimally invasive and provide an attractive option to detect biomarkers, avoiding stressful medical procedures. This systematic review aims to evaluate the possibility of a non-invasive biomarker signature that can guide therapeutic decisions. The studies reported here offer valuable insight into how circulating biomarkers can have a role in personalized treatments for melanoma patients receiving ICIs therapy, emphasizing the need for rigorous clinical trials to confirm findings and establish standardized procedures.

Sensitivity enhancement of bimodal waveguide interferometric sensor based on regional mode engineering

In this paper, we propose a novel bimodal waveguide based on regional mode engineering (BiMW-RME). Leveraging the orthogonality of the guided modes, the form of patterned SiO2 cladding on the bimodal waveguide can reduce the interaction between the reference mode and the analyte, thereby significantly improving sensitivity. The proposed BiMW-RME sensor experimentally demonstrates a phase sensitivity of 2766 π rad/RIU/cm and a detection limit of 2.44×1-5 RIU. The sensitivity is 2.7 times higher than that of the conventional BiMW sensor on the same SOI platform. The proposed design strategy demonstrates a significant improvement in the sensor's sensitivity, presenting a novel approach to enhancing common-path interferometric sensor performance.

Selective miR-21 detection technology based on photocrosslinkable artificial nucleic acid-modified magnetic particles and hybridization chain reaction

Recently, microRNA (miRNA) detection in blood has attracted attention as a new early detection technology for cancer. The extraction of target miRNA is a necessary preliminary step for detection; however, currently, most extraction methods extract all RNA from the blood, which limits the detection selectivity. Therefore, a method for the selective extraction and detection of target miRNA from blood is very important. In this study, we utilized photocrosslinkable artificial nucleic acids and the hybridization chain reaction (HCR) in an attempt to improve upon the current standard method RT-qPCR, which is hampered by problems with primer design and enzymatic amplification. By introducing photocrosslinkable artificial nucleic acids to oligonucleotide probes modified with magnetic particles with a sequence complementary to that of the target miRNA and irradiating them with light, covalent bonds were formed between the target miRNA and the oligonucleotide probes. These tight covalent bonds enabled the capture of miRNA in blood, and intensive washing ensured that only the target miRNA were extracted. After extraction, two types of DNA (H1 and H2) modified with fluorescent dyes were added and the fluorescence signals were amplified by the HCR in the presence of the target miRNA bound to the photocrosslinkable artificial nucleic acids, allowing for isothermal and enzyme-free miRNA detection. The novel method is suitable for selective miRNA detection in real blood samples. Because the reaction proceeds isothermally and no specialized equipment is used for washing, this detection technology is simple and selective and suitable for application to point-of-care technology using microfluidic devices.

Dual-targets fluorescent nanoprobe for precise subtyping of lung cancer

A Au-Se bond-based nanoprobe using 3',3-diselenopropionic acid to simultaneously link response chains for Pro-GRP protein and Cyfra21-1 was developed. Early diagnosis and subtyping of lung cancer can be achieved based on the nanoprobes' differential response of the probes to the two targets in lung cancer patients' serum.

Pt-Se-Bonded Nanoprobe for High-Fidelity Detection of Non-small Cell Lung Cancer and Enhancement of NIR II Photothermal Therapy

Non-small cell lung cancer (NSCLC) accounts for a high proportion of lung cancer cases globally, but early detection remains challenging, and insufficient oxygen supply at tumor sites leads to suboptimal treatment outcomes. Therefore, the development of core-shell Au@Pt-Se nanoprobes (Au@Pt-Se NPs) with peptide chains linked through Pt-Se bonds was designed and synthesized for NSCLC biomarker protein calcium-activated neutral protease 2 (CAPN2) and photothermal therapy (PTT) enhancement. The NP can be specifically cleaved by CAPN2, resulting in fluorescence recovery to realize the detection. The Pt-Se bonds exhibit excellent resistance to biologically abundant thiols such as glutathione, thus avoiding "false-positive" results and enabling precise detection of NSCLC. Additionally, the platinum (Pt) shell possesses catalase-like properties that catalyze the generation of oxygen from endogenous hydrogen peroxide within the tumor, thereby reducing hypoxia-inducible factor-1α (HIF-1α) levels and alleviating the hypoxic environment at the tumor site. The Au@Pt-Se NPs exhibit strong absorption bands, enabling the possibility of PTT in the near-infrared II region (NIR II). This study presents an effective approach for the early detection of NSCLC while also serving as an oxygen supplier to alleviate the hypoxic environment and enhance NIR II PTT.

Exploring the Potential of Non-Coding RNAs as Liquid Biopsy Biomarkers for Lung Cancer Screening: A Literature Review

Lung cancer represent the leading cause of cancer mortality, so several efforts have been focused on the development of a screening program. To address the issue of high overdiagnosis and false positive rates associated to LDCT-based screening, there is a need for new diagnostic biomarkers, with liquid biopsy ncRNAs detection emerging as a promising approach. In this scenario, this work provides an updated summary of the literature evidence about the role of non-coding RNAs in lung cancer screening. A literature search on PubMed was performed including studies which investigated liquid biopsy non-coding RNAs biomarker lung cancer patients and a control cohort. Micro RNAs were the most widely studied biomarkers in this setting but some preliminary evidence was found also for other non-coding RNAs, suggesting that a multi-biomarker based liquid biopsy approach could enhance their efficacy in the screening context. However, further studies are needed in order to optimize detection techniques as well as diagnostic accuracy before introducing novel biomarkers in the early diagnosis setting.

Integration of Metal-Organic Polyhedra onto a Nanophotonic Sensor for Real-Time Detection of Nitrogenous Organic Pollutants in Water

The grave health and environmental consequences of water pollution demand new tools, including new sensing technologies, for the immediate detection of contaminants in situ. Herein, we report the integration of metal-organic cages or polyhedra (MOCs/MOPs) within a nanophotonic sensor for the rapid, direct, and real-time detection of small (<500 Da) pollutant molecules in water. The sensor, a bimodal waveguide silicon interferometer incorporating Rh(II)-based MOPs as specific chemical receptors, does not require sample pretreatment and enables minimal expenditure of time and reagents. We validated our sensor for the detection of two common pollutants: the industrial corrosion inhibitor 1,2,3-benzotriazole (BTA) and the systemic insecticide imidacloprid (IMD). The sensor offers a fast time-to-result response (15 min), high sensitivity, and high accuracy. The limit of detection (LOD) in tap water for BTA is 0.068 μg/mL and for IMD, 0.107 μg/mL, both of which are below the corresponding toxicity thresholds defined by the European Chemicals Agency (ECHA). By combining innovative chemical molecular receptors such as MOPs with state-of-the-art photonic sensing technologies, our research opens the path to implement competitive sensor devices for in situ environmental monitoring.

Solid-Phase Optical Sensing Techniques for Sensitive Virus Detection

Viral infections can pose a major threat to public health by causing serious illness, leading to pandemics, and burdening healthcare systems. The global spread of such infections causes disruptions to every aspect of life including business, education, and social life. Fast and accurate diagnosis of viral infections has significant implications for saving lives, preventing the spread of the diseases, and minimizing social and economic damages. Polymerase chain reaction (PCR)-based techniques are commonly used to detect viruses in the clinic. However, PCR has several drawbacks, as highlighted during the recent COVID-19 pandemic, such as long processing times and the requirement for sophisticated laboratory instruments. Therefore, there is an urgent need for fast and accurate techniques for virus detection. For this purpose, a variety of biosensor systems are being developed to provide rapid, sensitive, and high-throughput viral diagnostic platforms, enabling quick diagnosis and efficient control of the virus's spread. Optical devices, in particular, are of great interest due to their advantages such as high sensitivity and direct readout. The current review discusses solid-phase optical sensing techniques for virus detection, including fluorescence-based sensors, surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), optical resonators, and interferometry-based platforms. Then, we focus on an interferometric biosensor developed by our group, the single-particle interferometric reflectance imaging sensor (SP-IRIS), which has the capability to visualize single nanoparticles, to demonstrate its application for digital virus detection.

Ultrasensitive Hybridization Chain Reaction-Assisted Multisite Exonuclease III Amplification Strategy Combined with a Direct Quantitative Fluorescence Lateral Flow Technique for Multiple Bacterial 16S rRNA Detection

Accurate and in-time detection of bacteria conduces to preventing their rapid spread around the environment, while a nucleic acid test (NAT) is a powerful tool for early diagnosis of pathogens. Herein, we propose a hybridization chain reaction (HCR)-mediated multisite exonuclease III (Exo-III) amplification strategy (HCR/Exo-III amplifier) to achieve the one-pot and ultrasensitive isothermal amplification of bacterial 16S rRNA and a portable fluorescence detection device (PFD) to directly read signals in a lateral flow assay (LFA). In detail, the target-initiated HCR products present multiple binding sites for triggering the Exo-III amplifier that produces numerous target amplicons. Following that, the target amplicons travel up on the strip and bridge between the DNA-CdTe/CdS probes and the capture DNA to form a positive fluorescence line. After that, the strip is inserted into the PFD to accomplish the fluorescence signal reading. The constructed HCR/Exo-III amplifier-based PFD-LFA implemented the simultaneous and specific detection of three bacteria with a detection limit of a few tenths of fM for synthetic 16S rRNA fragments and dozens of CFU/mL for Staphylococcus aureus, Listeria monocytogenes, and Salmonella typhimurium in pure cultures. The sensing platform features isothermal amplification, convenient operation, and good economy, displaying great potential for on-site testing toward multiple nucleic acid analytes.

Functionalization of a Fully Integrated Electrophotonic Silicon Circuit for Biotin Sensing

Electrophotonic (EPh) circuits are novel systems where photons and electrons can be controlled simultaneously in the same integrated circuit, attaining the development of innovative sensors for different applications. In this work, we present a complementary metal-oxide-semiconductor (CMOS)-compatible EPh circuit for biotin sensing, in which a silicon-based light source is monolithically integrated. The device is composed of an integrated light source, a waveguide, and a p-n photodiode, which are all fabricated in the same chip. The functionalization of the waveguide's surface was investigated to biotinylate the EPh system for potential biosensing applications. The modified surfaces were characterized by AFM, optical microscopy, and Raman spectroscopy, as well as by photoluminescence measurements. The changes on the waveguide's surface due to functionalization and biotinylation translated into different photocurrent intensities detected in the photodiode, demonstrating the potential uses of the EPh circuit as a biosensor.