Applications of magnetic materials in the fabrication of microfluidic-based sensing systems: Recent advances

Recent advances in carbon-based materials derived from diverse green biowaste for sensing applications: a comprehensive overview from the perspective of synthesis method and application

The rapid increase in global waste, driven by population growth, has raised significant environmental concerns. Among different types of wastes, green biowastes (BWs) containing organic matter have attracted considerable attention. The conversion of BW, particularly from herbaceous and animal sources, to carbon-based materials (CBMs) introduces a suitable platform for waste management and resource recovery. Furthermore, this strategy creates valuable materials from low-value waste for various applications, sensing included. The abundance of these wastes provides a sustainable and affordable raw material and enhances the feasibility of fabricating these materials. Generally, the presence of carbon in their structure can present an accessible resource for producing different carbon materials, especially carbon dots (CDs), carbon quantum dots (CQDs), and graphene quantum dots (GQDs). The performance of these CBMs has been enhanced by optimizing synthesis processes, incorporating functional groups, and integrating various materials. The synthesized CBMs possess desirable features, such as biocompatibility, excellent physical, chemical, and electrical conductivity. These materials have been used in different sensors such as electrochemical (EC) and optical sensors for presenting high performance sensing probes with several benefits such as real-time monitoring, rapid detection, and high sensitivity. The first section of this review is dedicated to the preparation of CBMs, derived from green BWs, by different synthesized methods for use in different fields including biomedical application, food safety, and environmental monitoring. In addition, the challenges, limitations, and future directions in the development of these CBMs were completely discussed to improve their performance.

Panoramic view of artificial fruit ripening agents sensing technologies and the exigency of developing smart, rapid, and portable detection devices: A review

Recently, the availability of point-of-care sensor systems has led to the rapid development of smart and portable devices for the detection of hazardous analytes. The rapid flow of artificially ripened fruits into the market is associated with an elevated risk to human life, agriculture, and the ecosystem due to the use of artificial fruit ripening agents (AFRAs). Accordingly, there is a need for the development of "Point-of-care Sensors" to detect AFRAs due to several advantages, such as simple operation, promising detection mechanism, higher selectivity and sensitivity, compact, and portable. Traditional detection approaches are time-consuming and inappropriate for on-the-spot analyses. Presented comprehensive review aimed to reveal how such technology has systematically evolved over time (through conventional, advanced, and portable smart techniques) detection detect AFRA, till date. Moreover, focuses and highlights a framework of initiatives undertaken for technological advancements in the development of smart the portable detection techniques (kits) for the onsite detection of AFRAs in fruits with in-depth discussion over sensing mechanism and analytical performance of the sensing technology. Notably, colorimetric detection methods have the greatest potential for real-time monitoring of AFRA and its residues because they are easy to assemble, have a high level of selectivity and sensitivity, and can be read by the human eye independently. This study sought to differentiate between traditional credible strategies by presenting new prospects, perceptions, and challenges related to portable devices. This review provides systematic framework of advances in portable field recognition strategies for the on-spot AFRA detection in fruits and critical information for development of new paper-based portable sensors for fruit diagnostic sectors.

Aptamer Based Nanoprobes for Detection of Foodborne Virus in Food and Environment Samples: Recent Progress and Challenges

Accepting the fact that there is a huge number of virus particles in food that lead to several infectious diseases, eliminating of the foodborne virus from food is tangible. In 2020, the appearance of new SARS-CoV-2 variants had remarked the importance of food safety in our lives. Detection virus is a dynamic domain. Recently, many papers have tried to detect several foodborne viruses by using conventional sensing platforms including ELISA (enzyme-linked immunosorbent assay), PCR (polymerase chain reaction-based methods) and NASBA (nucleic acid sequence-based amplification). However, small sizes, low infective doses and discrete distribution of the foodborne virus have converted these microorganisms into the most challengeable pathogen in the food samples matrix. Foodborne virus detection exploiting aptamer-based biosensors has attracted considerable attention toward the numerous benefits of sourcing from aptamers in which a variety of viruses could be detected by conjugation of aptamer-virus. The development of multiple sensing methodologies and platforms in terms of aptasensor application in real food and environment samples has demonstrated promising results. In this review, we present the latest developments in myriad types of aptasensors (including electrochemical, optical and piezoelectric aptasensor) for the quantification of foodborne viruses. Working strategies, benefits and disadvantages of these platforms are argued.

Identification and Quantification of Extracellular Vesicles: Comparison of SDS-PAGE Analysis and Biosensor Analysis with QCM and IDT Chips

This study presents and compares two methods for identifying the types of extracellular vesicles (EVs) from different cell lines. Through SDS-PAGE analysis, we discovered that the ratio of CD63 to CD81 in different EVs is consistent and distinct, making it a reliable characteristic for recognizing EVs secreted by cancer cells. However, the electrophoresis and imaging processes may introduce errors in the concentration values, especially at lower concentrations, rendering this method potentially less effective. An alternative approach involves the use of quartz crystal microbalance (QCM) and electroanalytical interdigitated electrode (IDT) biosensors for EV type identification and quantification. The QCM frequency shift caused by EVs is directly proportional to their concentration, while electroanalysis relies on measuring the curvature of the I-V curve as a distinguishing feature, which is also proportional to EV concentration. Linear regression lines for the QCM frequency shift and the electroanalysis curvature of various EV types are plotted separately, enabling the estimation of the corresponding concentration for an unknown EV type on the graphs. By intersecting the results from both biosensors, the unknown EV type can be identified. The biosensor analysis method proves to be an effective means of analyzing both the type and concentration of EVs from different cell lines.

Integrating of analytical techniques with enzyme-mimicking nanomaterials for the fabrication of microfluidic systems for biomedical analysis

Bioanalysis faces challenges in achieving fast, reliable, and point-of-care (POC) determination methods for timely diagnosis and prognosis of diseases. POC devices often display lower sensitivity compared to laboratory-based methods, limiting their ability to quantify low concentrations of target analytes. To enhance sensitivity, the synthesis of new materials and improvement of the efficiency of the analytical strategies are necessary. Enzyme-mimicking materials have revolutionized the field of the fabrication of new high-throughput sensing devices. The integration of microfluidic chips with analytical techniques offers several benefits, such as easy miniaturization, need for low biological sample volume, etc., while also enhancing the sensitivity of the probe. The use enzyme-like nanomaterials in microfluidic systems can offer portable strategies for real-time and reliable detection of biological agents. Colorimetry and electrochemical methods are commonly utilized in the fabrication of nanozyme-based microfluidic systems. The review summarizes recent developments in enzyme-mimicking materials-integrated microfluidic analytical methods in biomedical analysis and discusses the current challenges, advantages, and potential future directions.

Magnetic nanoparticles fabricated/integrated with microfluidics for biological applications: A review

Nanostructured materials have gained significant attention in recent years for their potential in biological applications, such as cell and biomolecular sorting, as well as early detection of metastatic cancer. Among these materials, magnetic nanoparticles (MNPs) stand out for their easy functionalization, high specific surface area, chemical stability, and superparamagnetic properties. However, conventional fabrication methods can lead to inconsistencies in MNPs' characteristics and performance, highlighting the need for a cost-effective, controllable, and reproducible synthesis approach. In this review, we will discuss the utilization of microfluidic technology as a cutting-edge strategy for the continuous and regulated synthesis of MNPs. This approach has proven effective in producing MNPs with a superior biomedical performance by offering precise control over particle size, shape, and surface properties. We will examine the latest research findings on developing and integrating MNPs synthesized through continuous microfluidic processes for a wide range of biological applications. By providing an overview of the current state of the field, this review aims to showcase the advantages of microfluidics in the fabrication and integration of MNPs, emphasizing their potential to revolutionize diagnostic and therapeutic methods within the realm of biotechnology.

Aptamer-Magnetic Nanoparticle Complexes for Powerful Biosensing: A Comprehensive Review

The selective and sensitive diagnosis of diseases is a significant matter in the early stages of the cure of illnesses. To elaborate, although several types of probes have been broadly applied in clinics, magnetic nanomaterials-aptamers, as new-generation probes, are becoming more and more attractive. The presence of magnetic nanomaterials brings about quantification, purification, and quantitative analysis of biomedical, especially in complex samples. Elaborately, the superparamagnetic properties and numerous functionalized groups of magnetic nanomaterials are considered two main matters for providing separation ability and immobilization substrate, respectively. In addition, the selectivity and stability of aptamer can present a high potential recognition element. Importantly, the integration of aptamer and magnetic nanomaterials benefits can boost the performance of biosensors for biomedical analysis by introducing efficient and compact probes that need low patient samples and fast diagnosis, user-friendly application, and high repeatability in the quantification of biomolecules. The primary aim of this review is to suggest a summary of the effect of the employed other types of nanomaterials in the fabrication of novel aptasensors-based magnetic nanomaterials and to carefully explore various applications of these probes in the quantification of bioagents. Furthermore, the application of these versatile and high-potential probes in terms of the detection of cancer cells and biomarkers, proteins, drugs, bacteria, and nucleoside were discussed. Besides, research gaps and restrictions in the field of biomedical analysis by magnetic nanomaterials-aptamers will be discussed.

Detection of pioglitazone based on dual-emission ratiometric fluorescence probe consisting of ZIF8 and to L-ASC-AuNP/DA nanoparticles

A simple and sensitive dual-emission ratiometric fluorescent probe was developed using zeolitic imidazolate framework 8 (ZIF8) and L-ascorbic acid Au-doped dopamine nanoparticles (ZIF8/L-ASC-AuNP/DA NP) for the determination of pioglitazone (Pio), an oral hypoglycemic agent and insulin sensitizer, in real samples. The prepared system was based on the Pio-enhanced dual-emission intensity of ZIF8/L-ASC-AuNP/DA NP. The potential impact of various parameters on the system's emission intensity was tested. According to the findings, there is a strong linear correlation between the system's turn-on fluorescence intensity and Pio concentrations in the range 0.3 nM to 30.0 μM. The obtained value for the limit of detection (LOD) was 0.14 nM. In addition, the intra- and inter-day accuracy of the nanoprobe was studied and the findings revealed satisfactory precision and accuracy of the system. The short-term and freeze-thaw stability of Pio in plasma samples was evaluated and the results indicated the high stability of the developed nanoprobe under the test conditions. Pio was accurately detected in human plasma samples under ideal conditions with analytical recoveries in the range 86.0 - 109.3%. The results showed that the devised probe may be employed as an easy, sensitive, and precise approach for detecting Pio in real samples.

Overview on the Design of Magnetically Assisted Electrochemical Biosensors

Electrochemical biosensors generally require the immobilization of recognition elements or capture probes on the electrode surface. This may limit their practical applications due to the complex operation procedure and low repeatability and stability. Magnetically assisted biosensors show remarkable advantages in separation and pre-concentration of targets from complex biological samples. More importantly, magnetically assisted sensing systems show high throughput since the magnetic materials can be produced and preserved on a large scale. In this work, we summarized the design of electrochemical biosensors involving magnetic materials as the platforms for recognition reaction and target conversion. The recognition reactions usually include antigen-antibody, DNA hybridization, and aptamer-target interactions. By conjugating an electroactive probe to biomolecules attached to magnetic materials, the complexes can be accumulated near to an electrode surface with the aid of external magnet field, producing an easily measurable redox current. The redox current can be further enhanced by enzymes, nanomaterials, DNA assemblies, and thermal-cycle or isothermal amplification. In magnetically assisted assays, the magnetic substrates are removed by a magnet after the target conversion, and the signal can be monitored through stimuli-response release of signal reporters, enzymatic production of electroactive species, or target-induced generation of messenger DNA.

Gold-Nanoparticle-Coated Magnetic Beads for ALP-Enzyme-Based Electrochemical Immunosensing in Human Plasma

A simple and sensitive AuNP-coated magnetic beads (AMB)-based electrochemical biosensor platform was fabricated for bioassay. In this study, AuNP-conjugated magnetic particles were successfully prepared using biotin-streptavidin conjugation. The morphology and structure of the nanocomplex were characterized by scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDX) and UV-visible spectroscopy. Moreover, cyclic voltammetry (CV) was used to investigate the effect of AuNP-MB on alkaline phosphatase (ALP) for electrochemical signal enhancement. An ALP-based electrochemical (EC) immunoassay was performed on the developed AuNP-MB complex with indium tin oxide (ITO) electrodes. Subsequently, the concentration of capture antibodies was well-optimized on the AMB complex via biotin-avidin conjugation. Lastly, the developed AuNP-MB immunoassay platform was verified with extracellular vesicle (EV) detection via immune response by showing the existence of EGFR proteins on glioblastoma multiforme (GBM)-derived EVs (10⁸ particle/mL) spiked in human plasma. Therefore, the signal-enhanced ALP-based EC biosensor on AuNP-MB was favorably utilized as an immunoassay platform, revealing the potential application of biosensors in immunoassays in biological environments.

Aptasensor Based on Microfluidic for Foodborne Pathogenic Bacteria and Virus Detection: A Review

In today's world, which is entangled with numerous foodborne pathogenic bacteria and viruses, it appears to be essential to rethink detection methods of these due to the importance of food safety in our lives. The vast majority of detection methods for foodborne pathogenic bacteria and viruses have suffered from sensitivity and selectivity due to the small size of these pathogens. Besides, these types of sensing approaches can improve on-site detection platforms in the fields of food safety. In recent, microfluidics systems as new emerging types of portable sensing approaches can introduce efficient and simple biodevice by integration with several analytical methods such as electrochemical, optical and colorimetric techniques. Additionally, taking advantage of aptamer as a selective bioreceptor in the sensing of microfluidics system has provided selective, sensitive, portable and affordable sensing approaches. Furthermore, some papers use increased data transferability ability and computational power of these sensing platforms by exploiting smartphones. In this review, we attempted to provide an overview of the current state of the recent aptasensor based on microfluidic for screening of foodborne pathogenic bacteria and viruses. Working strategies, benefits and disadvantages of these sensing approaches are briefly discussed.

Current Progress in Aptasensor for Ultra-Low Level Monitoring of Parkinson's Disease Biomarkers

In today's world, Parkinson's disease (PD) has been introduced as a long-term degenerative disorder of the central nervous system which mainly affects approximately more than ten million people worldwide. The vast majority of diagnostic methods for PD have operated based on conventional sensing platforms, while the traditional laboratory tests are not efficient for diagnosis of PD in the early stage due to symptoms of this common neurodegenerative syndrome starting slowly. The advent of the aptasensor has revolutionized the early-stage diagnosis of PD by measuring related biomarkers due to the myriad advantages of originating from aptamers which can be able to sensitive and selective capture various types of related biomarkers. The progress of numerous sensing platforms and methodologies in terms of biosensors based on aptamer application for PD diagnosis has revealed promising results. In this review, we present the latest developments in myriad types of aptasensors for the determination of related PD biomarkers. Working strategies, advantages and limitations of these sensing approaches are also mentioned, followed by prospects and challenges.