Cell Membrane-Anchored SERS Biosensor for the Monitoring of Cell-Secreted MMP-9 during Cell-Cell Communication

Transformative biomedical devices to overcome biomatrix effects

The emergence of high-performance biomedical devices and sensing technologies highlights the technological advancements in the field. Recently during COVID-19 pandemic, biosensors played an important role in medical diagnostics and disease monitoring. In the past few decades, biosensors have made impressive advances in terms of sensing capability, methodology, and applications, and modern biosensors show higher performance and functionality compared to traditional biosensing platforms. Currently, various biomedical devices are already in the market or on the verge of commercialization, such as disposable paper-based devices, lab-on-a-chip devices, wearable sensors, and artificial intelligence-assisted systems, all contributing to the evolution of digital health. Despite the promising features of detection methods for developing practical biosensors, there are substantial barriers to the commercialization of biomedical devices. An important challenge is the matrix effect in the detection of clinical samples. Although achieving low limit of detection values under controlled laboratory conditions is feasible, maintaining performance in real clinical samples is difficult. Matrix molecules present in these samples can interact with analytes, potentially affecting sensitivity, specificity, and sensor response. Approaches to reduce nonspecific adsorption and cross-reactivity are imperative for improving sensor performance. The detection of diagnostic biomarkers in complex biological matrices often requires laborious sample preparation, which may affect accuracy and precision. In this review, we highlight the recent efforts to detect analytes in real samples, both invasively and noninvasively, and underline technological advancements that mitigate the biomatrix effects. We also discuss commercially available biosensors and technologies promising commercial success, highlighting their potential effect on healthcare and diagnostics.

Assembly of DNA Networks on the Cell Membrane Enables Confined Detection of MMP-9 Secretion and Evaluation of Drug Efficacy

Proteases secreted by tumor cells have been employed as potential biomarkers for the early assessment of tumor metastasis risk. However, in situ monitoring of their secretion at the single-cell level remains a challenge due to their low abundance and diffusion into complex environments. Despite significant advancements in utilizing DNA as a versatile scaffold for constructing dynamic sensing systems due to its programmability and design flexibility, the spatial control of molecular sensing and imaging functions within living cells is particularly challenging. Herein, we developed a DNA network (termed cAME) by introducing acrylamide copolymers combined with aptamer technology to enable a confined detection of single-cell matrix metalloproteinase-9 (MMP-9) secretion for the assessment of tumor cell invasiveness and drug efficacy evaluation. The cAME was established from a combination of a detecting DNA copolymer (MDDC) containing an MMP-9 responsive aptamer sensor, an encapsulating DNA copolymer (EDC), and a cell membrane anchoring module (chol-A). By monitoring changes in fluorescence signals, real-time detection of MMP-9 activity in individual cells could be achieved. Using various cancer cell lines as models, the feasibility of the proposed confined detection strategy in assessing the heterogeneity of MMP-9 secretion among different subtypes of breast cancer cells was validated. Furthermore, by employing two drugs as models, the application value of the proposed confined detection strategy in rapid and sensitive evaluation of drug efficacy was demonstrated. This strategy contributed to the assessment of tumor metastasis risk while also providing new insights for evaluating the efficacy of antitumor drugs.

Peptide-based biosensor for real-time monitoring of protease biomarker activity using multi-parametric surface plasmon resonance spectroscopy

Matrix metalloproteinase-9 (MMP-9) is a key biomarker targeted in biosensing applications due to its involvement not only in maintaining good health but also in triggering various diseases such as cancer. While quantitative detection of MMP-9 is widely performed using bioanalytical detection kits such as enzyme-linked immunosorbent assay (ELISA), faster, label-free and real-time monitoring of MMP-9 activity would lead to improved disease diagnosis with better understanding of its role in underlying disease progression and development of therapeutic strategies. In this work, multi-parametric surface plasmon resonance spectroscopy (MP-SPR) is used to develop a highly sensitive MMP-9 sensor using immobilized synthetic peptides as MMP-9 substrates. Upon binding to MMP-9, the MMP-9 specific peptide is hydrolyzed between two sites of the amino acid sequence (P1 Gly and P1' Met), resulting in a decrease in the SPR signal response. The sensor detects different concentrations of MMP-9 in buffer and cell culture medium (RPMI-1640), indicating that it can be used under physiological conditions. The limit of detection (LOD) for MMP-9 in buffer is 0.34 pM and the linear detection range is between 5 pM and 9 nM, covering the clinically relevant detection range of MMP-9. To our knowledge, this is the first short synthetic peptide-based MP-SPR biosensor for monitoring MMP-9 activity. The sensor is faster than ELISA (minutes vs. hours) and provides real-time detection with access to binding kinetics information. The use of MP-SPR provides information on surface coverage and peptide thickness before and after cleavage, which is unique compared to other detection methods.

A highly sensitive and selective SERS sensors based on Au@PATP@Ag@ZIF-8 for the detection of phosphate in water

Rapid and sensitive detection of phosphate is of great significance for ensuring water safety and preventing eutrophication. In this study, we prepared Au@PATP@Ag NRs core-shell structures using 4-aminothiophenol (PATP) as an internal standard signal molecule to enhance the stability of the SERS signal. Based on the protective effect of ZIF-8 on the internal Au@PATP@Ag NRs and the phosphate-induced decomposition of ZIF-8, a phosphate SERS sensor (Au@PATP@Ag@ZIF-8) with high sensitivity, selectivity and stability was designed. This method exhibited a good linear range of 0.1-125 μM and a detection limit of 30 nM. Furthermore, the developed sensor (Au@PATP@Ag@ZIF-8) was effectively applied to assess PO43- in tap water samples, achieving recoveries between 97.44 % and 104.54 %. With its simple, fast and sensitive features, this method of phosphate detection in water provides a direction for the research and practical application of phosphate detection.

Applications of Matrix Metalloproteinase-9-Related Nanomedicines in Tumors and Vascular Diseases

Matrix metalloproteinase-9 (MMP-9) is implicated in tumor progression and vascular diseases, contributing to angiogenesis, metastasis, and extracellular matrix degradation. This review comprehensively examines the relationship between MMP-9 and these pathologies, exploring the underlying molecular mechanisms and signaling pathways involved. Specifically, we discuss the contribution of MMP-9 to tumor epithelial-mesenchymal transition, angiogenesis, and metastasis, as well as its involvement in a spectrum of vascular diseases, including macrovascular, cerebrovascular, and ocular vascular diseases. This review focuses on recent advances in MMP-9-targeted nanomedicine strategies, highlighting the design and application of responsive nanoparticles for enhanced drug delivery. These nanotherapeutic strategies leverage MMP-9 overexpression to achieve targeted drug release, improved tumor penetration, and reduced systemic toxicity. We explore various nanoparticle platforms, such as liposomes and polymer nanoparticles, and discuss their mechanisms of action, including degradation, drug release, and targeting specificity. Finally, we address the challenges posed by the heterogeneity of MMP-9 expression and their implications for personalized therapies. Ultimately, this review underscores the diagnostic and therapeutic potential of MMP-9-targeted nanomedicines against tumors and vascular diseases.

The culture of A549 cells and its secreted cytokine IL-6 monitoring on the designed multifunctional microfluidic chip

A multifunctional microfluidic chip integrated with perfusion cell culture and in situ SERS detection of cell secretion was designed and developed for the detection of IL-6 secretion from LPS-stimulation of A549 cells in this paper. Researching works were focused on A549 cell activity and secretion in the constructed LPS-stimulated A549 cells model. On the designed microchip, a bubble trap chamber was designed to remove the bubbles in the culture medium which could also be simultaneously preheated by a split hot plate. Then, a long-time perfusion culture process of 549 cells could be realized. Under the optimized conditions the A549 cells could be cultured and kept in good activity for more than 36 h. Subsequently, the model of interaction between LPS and A549 cells was established on the designed microchip. When LPS-stimulated A549 cells, the IL-6 which was one of the secretions formed in this process was detected quantitatively by SERS spectral technique. The silver-coated gold nano-stars were prepared and taken as a sensitive enhancing probe for the SERS detection of IL-6 secreted from LPS-stimulated A549 cells. The immunomagnetic beads, IL-6 antigen, and SERS probes were mixed and incubated in the microchip and form a sandwich structure which was captured by the permanent magnet in the detection zone for SERS detection. The reference material of IL-6 was used to establish the calibration curve, and the linear range and detection limit were 1-10000 pg/mL and 0.75 pg/mL, respectively. Then, the IL-6 secretion from LPS-stimulated A549 cells was detected hourly for 7 h by this established method. The process of LPS stimulation of A594 cells did not lead to a sustained increase in the SERS spectral signature of IL-6. Instead, IL6 secretion initially increased sharply, then decreased and eventually stabilized. It could be due to a potential mechanism that the cells self-regulated to mitigate the inflammatory effects in response to sustained stimulation. The proposed multifunctional microfluidic chip, characterized by high sensitivity and the ability to perform continuous hourly detection, exhibited significant application prospects in the study of external stimulation on cells.

Unraveling the significance of AGPAT4 for the pathogenesis of endometriosis via a multi-omics approach

Endometriosis is characterized by the ectopic proliferation of endometrial cells, posing considerable diagnostic and therapeutic challenges. Our study investigates AGPAT4's involvement in endometriosis pathogenesis, aiming to unveil new therapeutic targets. Our investigation by analyzing eQTL data from GWAS for preliminary screening. Subsequently, within the GEO dataset, we utilized four machine learning algorithms to precisely identify risk-associated genes. Gene validity was confirmed through five Mendelian Randomization methods. AGPAT4 expression was measured by Single-Cell Analysis, ELISA and immunohistochemistry. We investigated AGPAT4's effect on endometrial stromal cells using RNA interference, assessing cell proliferation, invasion, and migration with CCK8, wound-healing, and transwell assays. Protein expression was analyzed by western blot, and AGPAT4 interactions were explored using AutoDock. Our investigation identified 11 genes associated with endometriosis risk, with AGPAT4 and COMT emerging as pivotal biomarkers through machine learning analysis. AGPAT4 exhibited significant upregulation in both ectopic tissues and serum samples from patients with endometriosis. Reduced expression of AGPAT4 was observed to detrimentally impact the proliferation, invasion, and migration capabilities of endometrial stromal cells, concomitant with diminished expression of key signaling molecules such as Wnt3a, β-Catenin, MMP-9, and SNAI2. Molecular docking analyses further underscored a substantive interaction between AGPAT4 and Wnt3a.Our study highlights AGPAT4's key role in endometriosis, influencing endometrial stromal cell behavior, and identifies AGPAT4 pathways as promising therapeutic targets for this condition.

Structural engineering of mitochondria-targeted Au-Ag2S photosensitizers for enhanced photodynamic and photothermal therapy

Much effort has been devoted to designing diverse photosensitizers for efficient photodynamic therapy (PDT) and photothermal therapy (PTT) performance. However, the effect of PS morphology on the PDT and PTT performance needs to be further explored. In this work, a photosensitizer, Au-Ag2S nanoparticles functionalized with indocyanine green, caspase-3 recognition peptides, and mitochondria-targeting peptides (AICM NPs) with different morphologies, including core-shell, eccentric core-shell-I, eccentric core-shell-II, and Janus morphologies, were synthesized to enhance PDT and PTT performance. Among them, AICM Janus NPs with enhanced charge-transfer efficiency and photothermal conversion demonstrate superior PDT and PTT performance compared to those of other morphologies. In addition, AICM NPs exhibit satisfactory surface-enhanced Raman scattering performance for in situ SERS monitoring of caspase-3 during PDT and PTT processes. After PDT and PTT treatment with AICM Janus NPs, the damaged mitochondria released caspase-3. AICM Janus NPs achieved a superior apoptosis rate in tumor cells in vitro. Furthermore, AICM Janus NPs treat the tumors in vivo within only 10 days, which is half the time reported in other work. The AICM NPs demonstrated superior therapeutic safety both in vitro and in vivo. This study investigates the effects of morphology-property-performance of photosensitizers on the PDT and PTT performances, which opens a new pathway toward designing photosensitizers for efficient PDT and PTT.

Aversatile MOF as an electrochemical/fluorescence/colorimetric signal probe for the tri-modal detection of MMP-9 secretion in the extracellular matrix to identify the efficacy of chemotherapeutic drugs

BACKGROUND

MMP-9 plays a crucial role in regulating the degradation of proteins within the extracellular matrix (ECM). This process closely correlates with the occurrence, development, invasion, and metastasis of various tumors, each exhibiting diverse levels of MMP-9 expression. However, the accuracy of detection results using the single-mode method is compromised due to the coexistence of multiple biologically active substances in the ECM.

RESULTS

Therefore, in this study, a tri-modal detection system is proposed to obtain more accurate information by cross-verifying the results. Herein, we developed a tri-modal assay using the ZIF-8@Au NPs@S QDs composite as a multifunctional signal probe, decorated with DNA for the specific capture of MMP9. Notably, the probe demonstrated high conductivity, fluorescence response and mimicked enzyme catalytic activity. The capture segments of hybrid DNA specifically bind to MMP9 in the presence of MMP9, causing the signal probe to effortlessly detach the sensor interface onto the sample solution. Consequently, the sensor current performance is weakened, with the colorimetric and fluorescent signals becoming stronger with increasing MMP9 concentration. Notably, the detection range of the tri-modal sensor platform spans over 10 orders of magnitude, verifying notable observations of MMP-9 secretion in four tumor cell lines with chemotherapeutic drugs. Furthermore, the reliability of the detection results can be enhanced by employing pairwise comparative analysis.

SIGNIFICANCE

This paper presents an effective strategy for detecting MMP9, which can be utilized for both the assessment of MMP-9 in cell lines and for analyzing the activity and mechanisms involved in various tumors.

Recent progress in Surface-Enhanced Raman Spectroscopy detection of biomarkers in liquid biopsy for breast cancer

Breast cancer is the most commonly diagnosed cancer in women globally and a leading cause of cancer-related mortality. However, current detection methods, such as X-rays, ultrasound, CT scans, MRI, and mammography, have their limitations. Recently, with the advancements in precision medicine and technologies like artificial intelligence, liquid biopsy, specifically utilizing Surface-Enhanced Raman Spectroscopy (SERS), has emerged as a promising approach to detect breast cancer. Liquid biopsy, as a minimally invasive technique, can provide a temporal reflection of breast cancer occurrence and progression, along with a spatial representation of overall tumor information. SERS has been extensively employed for biomarker detection, owing to its numerous advantages such as high sensitivity, minimal sample requirements, strong multi-detection ability, and controllable background interference. This paper presents a comprehensive review of the latest research on the application of SERS in the detection of breast cancer biomarkers, including exosomes, circulating tumor cells (CTCs), miRNA, proteins and others. The aim of this review is to provide valuable insights into the potential of SERS technology for early breast cancer diagnosis.

Importance of DNA nanotechnology for DNA methyltransferases in biosensing assays

DNA methylation is the process by which specific bases on a DNA sequence acquire methyl groups under the catalytic action of DNA methyltransferases (DNMT). Abnormal changes in the function of DNMT are important markers for cancers and other diseases; therefore, the detection of DNMT and the selection of its inhibitors are critical to biomedical research and clinical practice. DNA molecules can undergo intermolecular assembly to produce functional aggregates because of their inherently stable physical and chemical properties and unique structures. Conventional DNMT detection methods are cumbersome and complicated processes; therefore, it is necessary to develop biosensing technology based on the assembly of DNA nanostructures to achieve rapid analysis, simple operation, and high sensitivity. The design of the relevant program has been employed in life science, anticancer drug screening, and clinical diagnostics. In this review, we explore how DNA assembly, including 2D techniques like hybridization chain reaction (HCR), rolling circle amplification (RCA), catalytic hairpin assembly (CHA), and exponential isothermal amplified strand displacement reaction (EXPAR), as well as 3D structures such as DNA tetrahedra, G-quadruplexes, DNA hydrogels, and DNA origami, enhances DNMT detection. We highlight the benefits of these DNA nanostructure-based biosensing technologies for clinical use and critically examine the challenges of standardizing these methods. We aim to provide reference values for the application of these techniques in DNMT analysis and early cancer diagnosis and treatment, and to alert researchers to challenges in clinical application.