Rapid and simultaneous detection of heart-type fatty acid binding protein and cardiac troponin using a lateral flow assay based on metal organic framework@CdTe nanoparticles

A nanoparticle-assisted signal-enhancement technique for lateral flow immunoassays

Lateral flow immunoassay (LFIA), an affordable and rapid paper-based detection technology, is employed extensively in clinical diagnosis, environmental monitoring, and food safety analysis. The COVID-19 pandemic underscored the validity and adoption of LFIA in performing large-scale clinical and public health testing. The unprecedented demand for prompt diagnostic responses and advances in nanotechnology have fueled the rise of next-generation LFIA technologies. The utilization of nanoparticles to amplify signals represents an innovative approach aimed at augmenting LFIA sensitivity. This review probes the nanoparticle-assisted amplification strategies in LFIA applications to secure low detection limits and expedited response rates. Emphasis is placed on comprehending the correlation between the physicochemical properties of nanoparticles and LFIA performance. Lastly, we shed light on the challenges and opportunities in this prolific field.

Portable fluorescent lateral flow assay for ultrasensitive point-of-care analysis of acute myocardial infarction related microRNA

Point-of-care quantitative analysis of tracing microRNA disease-biomarkers remains a great challenge in the clinical diagnosis. In this paper, we developed a portable fluorescent lateral flow assay for ultrasensitive quantified detection of acute myocardial infarction related microRNAs in bio-samples. SiO2@DQD (bilayer quantum dots assembly with SiO2 core) based fluorescent lateral flow strip was fabricated as the analysis tool. In order to quantify the tracing microRNA in biosamples, a catalytic hairpin assembly and CRISPR/Cas12a cascade amplification method was performed and combined with the fabricated SiO2@DQD lateral flow strip. Thus, our platform gathered double advantages of portability and ultrasensitive quantification. Based on our strips, target myocardial biomarker microRNA-133a can be detected with a detection limit of 0.32 fM, which was almost 1000-fold sensitive compared with previous reported microRNAs-lateral flow strips. Significantly, this portable fluorescent strip can directly detect microRNAs in serum without any pretreatment and PCR amplification steps. When spiked in serum samples, a recovery of 99.65 %-102.38 % can be obtained. Therefore, our method offers a potential tool for ultrasensitive quantification of diseases related microRNA in the point-of-care diseases diagnosis field.

Deep Learning-Enabled Multiplexed Point-of-Care Sensor using a Paper-Based Fluorescence Vertical Flow Assay

Multiplexed computational sensing with a point-of-care serodiagnosis assay to simultaneously quantify three biomarkers of acute cardiac injury is demonstrated. This point-of-care sensor includes a paper-based fluorescence vertical flow assay (fxVFA) processed by a low-cost mobile reader, which quantifies the target biomarkers through trained neural networks, all within <15 min of test time using 50 µL of serum sample per patient. This fxVFA platform is validated using human serum samples to quantify three cardiac biomarkers, i.e., myoglobin, creatine kinase-MB, and heart-type fatty acid binding protein, achieving less than 0.52 ng mL-1 limit-of-detection for all three biomarkers with minimal cross-reactivity. Biomarker concentration quantification using the fxVFA that is coupled to neural network-based inference is blindly tested using 46 individually activated cartridges, which shows a high correlation with the ground truth concentrations for all three biomarkers achieving >0.9 linearity and <15% coefficient of variation. The competitive performance of this multiplexed computational fxVFA along with its inexpensive paper-based design and handheld footprint makes it a promising point-of-care sensor platform that can expand access to diagnostics in resource-limited settings.

High Bioaffinity Controllable Assembly Nanocarrier UiO-66-NH2@Quantum Dot-Based Immunochromatographic Assay for Simultaneous Detection of Five Mycotoxins in Cereals and Feed

Herein, the UiO-66-NH2@quantum dot (NU66@QD) was synthesized with excellent fluorescence intensity and biocompatibility, which was used to develop a multiple immunochromatographic assay (ICA) for the detection of aflatoxin B1 (AFB1), fumonisin B1 (FB1), deoxynivalenol (DON), T-2 toxins (T-2), and zearalenone (ZEN) in cereals and feed. Five monoclonal antibodies and NU66@QD were efficiently labeled by a one-step mixed method to form a multiple detection probe. The limits of detection of the proposed NU66@QD-ICA for AFB1/FB1/DON/T-2/ZEN were 0.04/0.28/0.25/0.09/0.08 μg/kg. The recoveries ranged from 82.83-117.44%, with the coefficient of variation from 2.88-11.80%. A parallel analysis in 35 naturally contaminated cereal and feed samples was confirmed by LC-MS/MS, and the results showed a good correlation (R2 > 0.9), indicating the practical reliability of the multiple NU66@QD-ICA. Overall, the introduction of the novel nanomaterial NU66@QD provides a highly sensitive and efficient multiplex detection strategy for the development of ICA.

One-pot synthesis of AuPt@FexOy nanoparticles with excellent peroxidase-like activity for development of ultrasensitive colorimetric lateral flow immunoassay of cardiac troponin I

Detection of cardiac troponin I (cTnI) plays a critical role in diagnosing acute myocardial infarction (AMI). In this report, a new kind of spherical AuPt@FexOy core@shell nanoparticles (termed as AuPt@FexOy NPs) were one-pot synthesized by a redox interaction-engaged strategy (RIES) without the addition of any surfactants or reducing agents. The as-synthesized AuPt@FexOy NPs not only retain the plasmonic activity of gold nanoparticles (AuNPs), but also possess excellent catalytic activities of platinum nanoparticles (PtNPs) and FexOy nanoclusters. The features of AuPt@FexOy NPs enable greatly enhance the colorimetric detection sensitivity of lateral flow immunoassay (LFIA) through integrating AuPt@FexOy NPs labeling procedure and catalyzing oxidation of chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) signal amplification strategy. The as-developed colorimetric LFIA (termed as AuPt@FexOy-LFIA) exhibits the limit of detection (LOD) as 26.0 pg mL-1 cTnI under the TMB signal amplification mode. In particular, the detection results of cTnI in 40 clinical seral samples by AuPt@FexOy-LFIA are correlated well with those of cTnI in the same samples by commercial enzyme-linked immunosorbent assay (ELISA) detection kit (R2 = 0.97, slope = 1), demonstrating the highly reliable analytical performance and good application prospect of AuPt@FexOy-LFIA.

Multititration: The New Method for Implementing Ultrasensitive and Quantitative Multiplexed In-Field Immunoassays Despite Cross-Reactivity?

The accurate in-field titration of multiple pathogens is essential to efficiently describe and monitor environmental or biological contamination, isolate, act, and treat adequately. This underscores the requirement of portable, fast, quantitative, and multiplexed detection technologies, which, however, have not been properly developed so far, notably because it has been hindered by the phenomenon of cross-reactivity. In this work, we proposed a new analytical method based on the imaging through a portable device of lanthanide-based nanoparticles (YVO4:Eu) for spatially multiplexed detection, relying on a multiparameter analysis, i.e., a simultaneous analysis of all of the luminescence signals through the comparison to a calibration surface built in the presence of multiple analytes of interest. We then demonstrated the possibility to simultaneously quantify by multiplexed lateral flow assay (xLFA) the three enterotoxins SEG, SEH, and SEI in unknown mixtures, over two concentration decades (from a dozen of pg·mL-1 to few ng·mL-1). Assays were performed in less than an hour (25 min of strip migration followed by 30 min of drying at room temperature), the time during which the presence of the operator was not required for more than 5 min, in order to dip the strip and have it imaged by the reader. The concepts of nominal concentration recovery, coefficient of variation (CV), limit of blank (LOB), and limit of detection (LOD) were discussed in detail in the context of multiplexed assays. With our new definitions, quantitative results demonstrated a high recovery of the nominal concentrations (115%), reliability (CV = 20%), and sensitivity (LOBs of 3, 27, and 6 pg·mL-1 for SEG, SEH, and SEI respectively, and LODs of 6, 48, and 11 pg·mL-1 for SEG, SEH, and SEI, respectively). Based on this method, we observed an increase in sensitivity of 100 compared to the other multiplexed LFA labeled with gold particles and we approached the sensitivity of the simplex enzyme-linked immunosorbent assay (ELISA) performed with the same capture and detection antibodies. To conclude, our results, which are applicable to virtually any kind of multiplexed test, pave the way to the next generation of in-field analytical immunoassays by providing fast, quantitative, and highly sensitive multiplexed detection of biomarkers or pathogens.

Fluorescence detection platform of metal-organic frameworks for biomarkers

Sensitive and selective detection of biomarkers is crucial in the study and early diagnosis of diseases. With the continuous development of biosensing technologies, fluorescent biosensors based on metal-organic frameworks have attracted increasing attention in the field of biomarker detection due to the combination of the advantages of MOFs, such as high specific surface area, large porosity, and structure with tunable functionality and the technical simplicity, sensitivity and efficiency and good applicability of fluorescent detection techniques. Therefore, researchers must understand the fluorescence response mechanism of such fluorescent biosensors and their specific applications in this field. Of all biomarkers applicable to such sensors, the chemical essence of nucleic acids, proteins, amino acids, dopamine, and other small molecules account for about a quarter of the total number of studies. This review systematically elaborates on four fluorescence response mechanisms: metal-centered emission (MC), ligand-centered emission (LC), charge transfer (CT), and guest-induced luminescence change (GI), presenting their applications in the detection of nucleic acids, proteins, amino acids, dopamine, and other small molecule biomarkers. In addition, the current challenges of MOFs-based fluorescent biosensors are also discussed, and their further development prospects are concerned.

Triple Enhancement for Sensitive Immunochromatographic Assay: A Case Study for Human Fatty Acid-Binding Protein Detection

The work considers a combination of three enhancing approaches for immunochromatographic assay (ICA) and the integration of their impacts into changes of the limit of detection (LOD). Human fatty acid binding protein (FABP), an early biomarker of acute myocardial infarction, was the target analyte. Starting from the common ICA protocol with an LOD equal to 11.2 ng/mL, three approaches were realized: (1) replacement of spherical gold nanoparticles with gold nanoflowers having a branched surface (20-fold lowering the LOD); (2) enhanced labeling of immune complexes via nanoparticle aggregates (15-fold lowering); (3) in-situ growth of bound nanoparticles by reduction of gold salts (3-fold lowering). Single and combined implementations of these approaches have been studied. It has been shown that the LOD decrease for combined approaches is close to the multiplied contribution of each of them. The final LOD for FABP was 0.05 ng/mL, which is 220 times lower than the LOD for the common ICA protocol. The efficiency of the enhanced ICA with three combined approaches was confirmed by testing human serum samples for FABP presence and content. The development presents a new efficient technique for rapid sensitive detection of FABP for medical diagnostics. Moreover, the demonstrated multiple enhancements could be applied for various demanded analytes.

Development of Lateral Flow Assays for Rapid Detection of Troponin I: A Review

Troponin I as a particular and major biomarker of cardiac failure is released to blood demonstrating hurt of myocardial cells. Unfortunately, troponin I detection in the first hours of acute myocardial infarction usually faces with most negligence. Therefore, developments of point of care devices such as lateral flow strips are highly required for timely diagnosis and prognosis. Lateral flow assays are low-cost paper-based detection platforms relying on specific diagnostic agents such as aptamers and antibodies for a rapid, selective, quantitative and semi-quantitative detection of the analyte in a complex mixture. Moreover, lateral flow assay devices are portable, and their simplicity of use eliminates the need for experts or any complicated equipment to operate and interpret the test results. Additionally, by coupling the lateral flow assay technology with nanotechnology, for labeling and signal amplification, many breakthroughs in the field of diagnostics have been achieved. The present study reviews the use of lateral flow assays in early stage, quantitative, and sensitive detection of cardiac troponin I and mainly focuses on the structure of each type of developed lateral flow assays. Finally, this review summarized the improvements, detection time, and limit of detection of each study as well as the advantages and disadvantages.

Flexible and High-Throughput Photothermal Biosensors for Rapid Screening of Acute Myocardial Infarction Using Thermochromic Paper-Based Image Analysis

Herein, we developed a flexible, low-cost thermosensitive fiber paper for the visual display in photothermal biosensing systems for early acute myocardial infarction. The thermal signal visualization device was encapsulated with rewritable thermal fibers, which exhibited excellent stability and reversibility. The mechanism of color change in thermal paper was based on a temperature-driven reversible transformation of the structure of the dye molecule (crystalline violet lactone, CVL). It exhibits a gradation from blue to colorless at higher temperatures and gradually returns to blue when the temperature drops. Immobilization and cascade enzymatic reactions of target molecules occurred in an integrated 3D-printed detection device, a photothermal conversion process occurred under near-infrared light excitation, and the colorimetric change values of the encapsulated thermal paper were recorded and evaluated for possible pathogenicity using a smartphone. It was worth noting that the effect of the thermogenic ring-opening behavior of CVL on the macroscopic phenomenon of color change was obtained by density functional theory calculations. Under optimized conditions, the naked-eye-recognizable range of the thermal paper-based photothermal immunoassay sensor was 0.2-20 ng mL^-1, This work creatively presents theoretical studies of promising thermal paper-based photothermal biosensors and provides new insights for the development of low-cost, instrument-free portable photothermal biosensors.

Toward Next Generation Lateral Flow Assays: Integration of Nanomaterials

Lateral flow assays (LFAs) are currently the most used point-of-care sensors for both diagnostic (e.g., pregnancy test, COVID-19 monitoring) and environmental (e.g., pesticides and bacterial monitoring) applications. Although the core of LFA technology was developed several decades ago, in recent years the integration of novel nanomaterials as signal transducers or receptor immobilization platforms has brought improved analytical capabilities. In this Review, we present how nanomaterial-based LFAs can address the inherent challenges of point-of-care (PoC) diagnostics such as sensitivity enhancement, lowering of detection limits, multiplexing, and quantification of analytes in complex samples. Specifically, we highlight the strategies that can synergistically solve the limitations of current LFAs and that have proven commercial feasibility. Finally, we discuss the barriers toward commercialization and the next generation of LFAs.

Recent advances in metal-organic frameworks and their composites for the phototherapy of skin wounds

Wound healing is a complex process that greatly affects the normal physiological activities of genes, proteins, signaling pathways, tissues, and organs. Bacterial infection could easily lead to serious tissue damage during wound healing, thus countering wound infections becomes a major challenge for clinicians and nursing professionals. At present, the exploration of highly effective, low toxicity and environment friendly methods for wound healing is attracting considerable interest all over the world. Recently, metal-organic frameworks (MOFs) have presented great potential for treating wound infections due to their unique characteristics of diversified functionality, large specific surface area, and high biocompatibility. These properties endow MOFs/MOF-based composites with an outstanding anti-wound infection effect, which is mainly attributed to the continuously released active components and the exerted catalytic activity with the assistance of phototherapy. In this review, the current progress of MOFs/MOF-based composites for the phototherapy of skin wounds is presented. Firstly, we illustrate the pathophysiological mechanisms, principles of phototherapy and the conventional methods for wound healing. Then, the structures and characteristics of MOFs are systematically summarized. Moreover, the review highlights the recent advances in the application of phototherapy for wound healing (including photodynamic therapy, photothermal therapy, and synergistic therapy) based on various MOFs/MOF-based composites. Finally, the challenges and perspectives are provided for the further development of MOF-based materials for medical application.

Highly Sensitive Lanthanide-Doped Nanoparticles-Based Point-of-Care Diagnosis of Human Cardiac Troponin I

Introduction

Methods

Results

Conclusion