Aptamer-Based Biosensors for the Colorimetric Detection of Blood Biomarkers: Paving the Way to Clinical Laboratory Testing

Aptamer biosensors for thrombin

Thrombin, a key factor in the coagulation cascade, is a valuable biomarker of great importance for the prognosis, diagnosis, and monitoring of various diseases, including cancer and heart disease. Due to the increasing attention to the development of point-of-care testing (POCT) options, various types of biosensors have been invented to enhance the accuracy and speed of detection of important biomarkers such as thrombin. Implementation of aptamers in biosensors (aptasensors) improves the target recognition capacity due to the high-affinity binding nature of aptamers. Herein, this review presents recent studies of aptasensors for thrombin detection based on different detection mechanisms encompassing optical biosensors, surface-enhanced Raman spectroscopy (SERS), electrochemical detection, piezoelectric detection, and lateral flow assay.

Advances in novel biosensors in biomedical applications

Biosensors, devices capable of detecting biomolecules or bioactive substances, have recently become one of the important tools in the fields of bioanalysis and medical diagnostics. A biosensor is an analytical system composed of biosensitive elements and signal-processing elements used to detect various biological and chemical substances. Biomimetic elements are key to biosensor technology and are the components in a sensor that are responsible for identifying the target analyte. The construction methods and working principles of biosensors based on synthetic biomimetic elements, such as DNAzyme, molecular imprinted polymers and aptamers, and their updated applications in biomedical analysis are summarised. Finally, the technical bottlenecks and future development prospects for biomedical analysis are summarised and discussed.

Microfluidic Optical Aptasensor for Small Molecules Based on Analyte-Tuned Growth of Gold Nanoseeds and Machine Learning-Enhanced Spectrum Analysis: Rapid Detection of Mycotoxins

Natural toxins, mainly small molecules, are a category of chemical hazards in agri-food systems that pose threats to both public health and food security. Current standard methods for monitoring these toxins, predominantly based on liquid chromatography-mass spectrometry, are costly, labor-intensive, and complex. This study presents the development of a novel microfluidic optical aptasensor for rapid detection of small molecules based on analyte-tuned growth of gold nanoseeds combined with machine learning-enhanced spectrum analysis. We discovered and optimized a previously unreported growth pattern of aptamer-coated nanoparticles in the presence of different concentrations of analyte, enabling the detection of a major mycotoxin in food. The entire analysis was miniaturized on a customized microfluidic platform, allowing for automated spectral acquisition with precise liquid manipulation. A machine learning model, based on random forest with feature engineering, was developed and evaluated for spectrum analysis, significantly enhancing the prediction of mycotoxin concentrations. This approach extended the detection limit determined by the conventional method (∼72 ppb with high variation) to a wider range of 10 ppb to 100 ppm with high accuracy (overall mean absolute percentage error of 5.7%). The developed analytical tool provides a promising solution for detecting small molecules and monitoring chemical hazards in agri-food systems and the environment.

Lattice matching enables construction of CaS@NaYF4 heterostructure with synergistically enhanced water resistance and luminescence for antibiotic detection

Rare earth (RE)-doped CaS phosphors have been widely used as light-emitting components in various fields. Nevertheless, the application of nanosized CaS particles is still significantly limited by their poor water resistance and weak luminescence. Herein, a lattice-matching strategy is developed by growing an inert shell of cubic NaYF4 phase on the CaS luminescent core. Due to their similarity in crystal structure, a uniform core-shell heterostructure (CaS:Ce3+@NaYF4) can be obtained, which effectively protects the CaS:Ce3+ core from degradation in aqueous environment and enhances its luminescence intensity. As a proof of concept, a label-free aptasensor is further constructed by combining core-shell CaS:Ce3+@NaYF4 and Au nanoparticles (AuNPs) for the ultrasensitive detection of kanamycin antibiotics. Based on the efficient FRET process, the detection linear range of kanamycin spans from 100 to 1000 nM with a detection limit of 7.8 nM. Besides, the aptasensor shows excellent selectivity towards kanamycin antibiotics, and has been successfully applied to the detection of kanamycin spiked in tap water and milk samples, demonstrating its high potential for sensing applications.

Bioactive Metal-Organic Frameworks as a Distinctive Platform to Diagnosis and Treat Vascular Diseases

Vascular diseases (VDs) pose the leading threat worldwide due to high morbidity and mortality. The detection of VDs is commonly dependent on individual signs, which limits the accuracy and timeliness of therapies, especially for asymptomatic patients in clinical management. Therefore, more effective early diagnosis and lesion-targeted treatments remain a pressing clinical need. Metal-organic frameworks (MOFs) are porous crystalline materials formed by the coordination of inorganic metal ions and organic ligands. Due to their unique high specific surface area, structural flexibility, and functional versatility, MOFs are recognized as highly promising candidates for diagnostic and therapeutic applications in the field of VDs. In this review, the potential of MOFs to act as biosensors, contrast agents, artificial nanozymes, and multifunctional therapeutic agents in the diagnosis and treatment of VDs from the clinical perspective, highlighting the integration between clinical methods with MOFs is generalized. At the same time, multidisciplinary cooperation from chemistry, physics, biology, and medicine to promote the substantial commercial transformation of MOFs in tackling VDs is called for.

Computational Frontiers in Aptamer-Based Nanomedicine for Precision Therapeutics: A Comprehensive Review

In the rapidly evolving landscape of nanomedicine, aptamers have emerged as powerful molecular tools, demonstrating immense potential in targeted therapeutics, diagnostics, and drug delivery systems. This paper explores the computational features of aptamers in nanomedicine, highlighting their advantages over antibodies, including selectivity, low immunogenicity, and a simple production process. A comprehensive overview of the aptamer development process, specifically the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) process, sheds light on the intricate methodologies behind aptamer selection. The historical evolution of aptamers and their diverse applications in nanomedicine are discussed, emphasizing their pivotal role in targeted drug delivery, precision medicine and therapeutics. Furthermore, we explore the integration of artificial intelligence (AI), machine learning (ML), Internet of Things (IoT), Internet of Medical Things (IoMT), and nanotechnology in aptameric development, illustrating how these cutting-edge technologies are revolutionizing the selection and optimization of aptamers for tailored biomedical applications. This paper also discusses challenges in computational methods for advancing aptamers, including reliable prediction models, extensive data analysis, and multiomics data incorporation. It also addresses ethical concerns and restrictions related to AI and IoT use in aptamer research. The paper examines progress in computer simulations for nanomedicine. By elucidating the importance of aptamers, understanding their superiority over antibodies, and exploring the historical context and challenges, this review serves as a valuable resource for researchers and practitioners aiming to harness the full potential of aptamers in the rapidly evolving field of nanomedicine.

Nuclear matrix protein 22 in bladder cancer

Bladder cancer (BC) is ranked as the ninth most common malignancy worldwide, with approximately 570,000 new cases reported annually and over 200,000 deaths. Cystoscopy remains the gold standard for the diagnosis of BC, however, its invasiveness, cost, and discomfort have driven the demand for the development of non-invasive, cost-effective alternatives. Nuclear matrix protein 22 (NMP22) is a promising non-invasive diagnostic tool, having received FDA approval. Traditional methods for detecting NMP22 require a laboratory environment equipped with specialized equipment and trained personnel, thus, the development of NMP22 detection devices holds substantial potential for application. In this review, we evaluate the NMP22 sensors developed over the past decade, including electrochemical, colorimetric, and fluorescence biosensors. These sensors have enhanced detection sensitivity and overcome the limitations of existing diagnostic methods. However, many emerging devices exhibit deficiencies that limit their potential clinical use, therefore, we propose how sensor design can be optimized to enhance the likelihood of clinical translation and discuss the future applications of NMP22 as a legacy biomarker, providing insights for the design of new sensors.

Central Countries' and Brazil's Contributions to Nanotechnology

Abstract:

Nanotechnology is a cornerstone of the scientific advances witnessed over the past few years. Nanotechnology applications are extensively broad, and an overview of the main trends worldwide can give an insight into the most researched areas and gaps to be covered. This document presents an overview of the trend topics of the three leading countries studying in this area, as well as Brazil for comparison. The data mining was made from the Scopus database and analyzed using the VOSviewer and Voyant Tools software. More than 44.000 indexed articles published from 2010 to 2020 revealed that the countries responsible for the highest number of published articles are The United States, China, and India, while Brazil is in the fifteenth position. Thematic global networks revealed that the standing-out research topics are health science, energy, wastewater treatment, and electronics. In a temporal observation, the primary topics of research are: India (2020), which was devoted to facing SARS-COV 2; Brazil (2019), which is developing promising strategies to combat cancer; China (2018), whit research on nanomedicine and triboelectric nanogenerators; the United States (2017) and the Global tendencies (2018) are also related to the development of triboelectric nanogenerators. The collected data are available on GitHub. This study demonstrates the innovative use of data-mining technologies to gain a comprehensive understanding of nanotechnology's contributions and trends and highlights the diverse priorities of nations in this cutting-edge field.

Biosensing Platforms for Cardiac Biomarker Detection

Myocardial infarction (MI) is a cardiovascular disease that occurs when there is an elevated demand for myocardial oxygen as a result of the rupture or erosion of atherosclerotic plaques. Globally, the mortality rates associated with MI are steadily on the rise. Traditional diagnostic biomarkers employed in clinical settings for MI diagnosis have various drawbacks, prompting researchers to investigate fast, precise, and highly sensitive biosensor platforms and technologies. Biosensors are analytical devices that combine biological elements with physicochemical transducers to detect and quantify specific compounds or analytes. These devices play a crucial role in various fields including healthcare, environmental monitoring, food safety, and biotechnology. Biosensors developed for the detection of cardiac biomarkers are typically electrochemical, mass, and optical biosensors. Nanomaterials have emerged as revolutionary components in the field of biosensing, offering unique properties that significantly enhance the sensitivity and specificity of the detection systems. This review provides a comprehensive overview of the advancements and applications of nanomaterial-based biosensing systems. Beginning with an exploration of the fundamental principles governing nanomaterials, we delve into their diverse properties, including but not limited to electrical, optical, magnetic, and thermal characteristics. The integration of these nanomaterials as transducers in biosensors has paved the way for unprecedented developments in analytical techniques. Moreover, the principles and types of biosensors and their applications in cardiovascular disease diagnosis are explained in detail. The current biosensors for cardiac biomarker detection are also discussed, with an elaboration of the pros and cons of existing platforms and concluding with future perspectives.

A colorimetric immunoassay for the detection of human vascular endothelial growth factor 165 (VEGF165) based on anti-VEGF-iron oxide nanoparticle conjugation

Vascular endothelial growth factor (VEGF) is an indispensable element in many physiological processes, while alterations in its level in the circulating system are signs of pathology-associated diseases. Therefore, its precise and selective detection is critical for clinical applications to monitor the progression of the pathology. In this study, an optical immunoassay biosensor was developed as a model study for detecting recombinant VEGF165. The VEGF165 sample was purified from recombinant Kluyveromyces lactis GG799 yeast cells. Indirect ELISA was used during the detection, wherein iron oxide nanoparticles (FeNPs) were utilized to obtain optical signals. The FeNPs were synthesized in the presence of lactose p-amino benzoic acid (LpAB). VEGF165 antibody was conjugated to the LpAB-FeNPs through EDC/NHS chemistry to convert the iron oxide nanoparticles into VEGF165 specific probes. The specificity of the prepared system was tested in the presence of potential serum-based interferents (i.e., glucose, urea, insulin, C-reactive protein, and serum amyloid A), and validation studies were performed in a simulated serum sample. The proposed immunoassay showed a wide detection range (0.5 to 100 ng/mL) with a detection limit of 0.29 ng/mL. These results show that the developed assay could offer a sensitive, simple, specific, reliable, and high-throughput detection platform that can be used in the clinical diagnostics of VEGF.

Aptamers' Potential to Fill Therapeutic and Diagnostic Gaps

More than 30 years ago, in 1990, three independent research groups published several papers demonstrating that genetics could be performed in vitro in the absence of living organisms or cells [...].

Aptasensors Based on Non-Enzymatic Peroxidase Mimics: Current Progress and Challenges

Immunoassays based on antibodies as recognizing elements and enzymes as signal-generating modules are extensively used now in clinical lab diagnostics, food, and environmental analyses. However, the application of natural enzymes and antibodies has some drawbacks, such as relatively high manufacturing costs, thermal instability, and lot-to-lot variations that lower the reproducibility of results. Oligonucleotide aptamers are able to specifically bind their targets with high affinity and selectivity, so they represent a prospective alternative to protein antibodies for analyte recognition. Their main advantages include thermal stability and long shelf life, cost-efficient chemical synthesis, and negligible batch-to-batch variations. At the same time, a wide variety of non-protein peroxidase mimics are now available that show strong potential to replace protein enzymes. Here, we review and analyze non-protein biosensors that represent a nexus of these two concepts: aptamer-based sensors (aptasensors) with optical detection (colorimetric, luminescent, or fluorescent) based on different peroxidase mimics, such as DNAzymes, nanoparticles, or metal-organic frameworks.

Novel Microsynthesis of High-Yield Gold Nanoparticles to Accelerate Research in Biosensing and Other Bioapplications

Gold nanoparticles (AuNPs) exhibit unique properties that make them appealing for applications in biosensing and other emerging fields. Despite the availability of numerous synthesis methods, important questions remain to be addressed regarding the volume effect on the synthesis yield and quality of AuNPs in the light of biosensing research. The present study addresses these issues by developing a novel microvolumetric citrate-reduction method to improve the synthesis of AuNPs, which were characterized by electronic microscopy, energy dispersive spectroscopy, zeta potential and colorimetric analysis. A comparison of the novel microsynthesis method with the standard Turkevich method demonstrated its superior performance in terms of yield, monodispersity, rapidity (in one step), reproducibility, and stability. The analytical behavior of AuNPs-based aptasensors prepared by microsynthesis was investigated using kanamycin detection and showed higher reproducibility and improved detection limits (3.4 times) compared to those of Turkevich AuNPs. Finally, the effect of pH was studied to demonstrate the suitability of the method for the screening of AuNP synthesis parameters that are of direct interest in biosensing research; the results showed an optimal pH range between 5.0 and 5.5. In summary, the approach described herein has the potential to improve research capabilities in biosensing, with the added benefits of lowering costs and minimizing waste generation in line with current trends in green nanotechnology.

Aptamers Versus Vascular Endothelial Growth Factor (VEGF): A New Battle against Ovarian Cancer

Cancer is one of the diseases that causes a high mortality as it involves unregulated and abnormal cell growth proliferation that can manifest in any body region. One of the typical ovarian cancer symptoms is damage to the female reproductive system. The death rate can be reduced through early detection of the ovarian cancer. Promising probes that can detect ovarian cancer are suitable aptamers. Aptamers, i.e., so-called chemical antibodies, have a strong affinity for the target biomarker and can typically be identified starting from a random library of oligonucleotides. Compared with other probes, ovarian cancer targeting using aptamers has demonstrated superior detection effectiveness. Various aptamers have been selected to detect the ovarian tumor biomarker, vascular endothelial growth factor (VEGF). The present review highlights the development of particular aptamers that target VEGF and detect ovarian cancer at its earliest stages. The therapeutic efficacy of aptamers in ovarian cancer treatment is also discussed.

Detection of Emerging Pollutants Using Aptamer-Based Biosensors: Recent Advances, Challenges, and Outlook

The synergistic potentialities of innovative materials that include aptamers have opened new paradigms in biosensing platforms for high-throughput monitoring systems. The available nucleobase functional moieties in aptamers offer exclusive features for bioanalytical sensing applications. In this context, compared to various in-practice biological recognition elements, the utilization of aptamers in detection platforms results in an extensive range of advantages in terms of design flexibility, stability, and sensitivity, among other attributes. Thus, the utilization of aptamers-based biosensing platforms is extensively anticipated to meet unaddressed challenges of various in-practice and standard analytical and sensing techniques. Furthermore, the superior characteristics of aptasensors have led to their applicability in the detection of harmful pollutants present in ever-increasing concentrations in different environmental matrices and water bodies, seeking to achieve simple and real-time monitoring. Considering the above-mentioned critiques and notable functional attributes of aptamers, herein, we reviewed aptamers as a fascinating interface to design, develop, and deploy a new generation of monitoring systems to aid modern bioanalytical sensing applications. Moreover, this review aims to summarize the most recent advances in the development and application of aptasensors for the detection of various emerging pollutants (EPs), e.g., pharmaceutical, and personal care products (PPCPs), endocrine-disrupting chemicals (EDCs), pesticides and other agricultural-related compounds, and toxic heavy elements. In addition, the limitations and current challenges are also reviewed, considering the technical constraints and complexity of the environmental samples.