A Rapid Colorimetric Sensor for Soluble Interleukin-2 Receptor α, Based on Aptamer-Adsorbed AuNP

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.

Development of a one-shot dual aptamer-based fluorescence nanosensor for rapid, sensitive, and label-free detection of periostin

Periostin is associated with several diseases, including cancers. Therefore, monitoring blood periostin levels is a powerful tool for diagnosing various diseases and identifying their severity. However, conventional detection methods pose several challenges, including high costs. To address these issues, we developed a novel one-shot dual aptamer-based fluorescence nanosensor for detecting periostin. The proposed nanosensor facilitates rapid, label-free, and sensitive detection of periostin using gold nanoprobes constructed by rhodamine-b isothiocyanate, PL2trunc aptamer, and gold nanoparticles and silver nanoprobes fabricated by the PL5trunc aptamer and silver nanoparticles. The two nanoprobes form a core-satellite structure by interacting with periostin, and the nanosensor detects periostin through the fluorescence regenerated by the increased proximity between them. The nanosensor successfully detected periostin with remarkable detection limits of 106.68 pM in buffer and 463.3 pM in serum-spiked conditions within 30 min without additional washing or signal amplification processes. Considering serum periostin levels in various diseases, the proposed nanosensor provides a suitable method for identifying patients with various diseases and determining disease severity. Moreover, the platform can be helpful as a practical method for on-site medical diagnosis because it can be adapted to detect other biomarkers simply by replacing the aptamer with other detection probes.

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

Clinical diagnostics for human diseases rely largely on enzyme immunoassays for the detection of blood biomarkers. Nevertheless, antibody-based test systems have a number of shortcomings that have stimulated a search for alternative diagnostic assays. Oligonucleotide aptamers are now considered as promising molecular recognizing elements for biosensors (aptasensors) due to their high affinity and specificity of target binding. At the moment, a huge variety of aptasensors have been engineered for the detection of various analytes, especially disease biomarkers. However, despite their great potential and excellent characteristics in model systems, only a few of these aptamer-based assays have been translated into practice as diagnostic kits. Here, we will review the current progress in the engineering of aptamer-based colorimetric assays as the most suitable format for clinical lab diagnostics. In particular, we will focus on aptasensors for the detection of blood biomarkers of cardiovascular, malignant, and neurodegenerative diseases along with common inflammation biomarkers. We will also analyze the main obstacles that have to be overcome before aptamer test systems can become tantamount to ELISA for clinical diagnosis purposes.

Biosensors based on aptamer-conjugated gold nanoparticles: A review

Simply synthetized gold nanoparticles have been highly used in medicine and biotechnology as a result of their biocompatibility, conductivity, and being easily functionalized with biomolecules such as aptamer. Aptamer-conjugated gold nanoparticle structures synergically possess characteristics of both aptamer and gold nanoparticles including high binding affinity, high biocompatibility, enhanced target selectivity, and long circulatory half-life. Aptamer-conjugated gold nanoparticles have extensively gained considerable attention for designing of biosensing systems due to their interesting optical and electrochemical features. Moreover, biosensors based on aptamer-gold nanoparticles are easy to use, with fast response, and inexpensive which make them ideal in individualized medicine, disease markers detection, food safety, and so forth. Moreover, due to high selectivity and biocompatibility of aptamer-gold nanoparticles, these biosensing platforms are ideal tools for targeted drug delivery systems. The application of this nanostructure as diagnostic and therapeutic tool has been developed for detection of cancer in the early stage by detecting cancer biomarkers, pathogens, proteins, toxins, antibiotics, adenosine triphosphate, and other small molecules. This review obviously demonstrates that this nanostructure effectively is applicable in the field of biomedicine and possesses potential of commercialization aims.

Application of the catalytic activity of gold nanoparticles for development of optical aptasensors

Biosensor technology is considered to be a great alternative in analytical techniques over the conventional methods. Among many recently developed techniques and devices, aptasensors are interesting because of their high specificity, selectivity and sensitivity. Combining aptamer as a biological recognition element with gold nanoparticles (AuNPs) as probe, are becoming more general owing to their beneficial properties, including low cost and ability to analyze specific targets on-site and using naked eye. Hydrogen bonds, nucleic acid hybridization, aptamer-target and antigen-antibody binding, Raman signature, enzyme inhibition, and enzyme-mimicking activity are main different sensing strategies exploited in AuNPs-based optical aptasensors. In this review article, we discussed the recent advances in optical aptasensors with a special emphasis on the catalytic activity property of AuNPs.

Lipoprotein (a) and coronary artery calcification: prospective study assessing interactions with other risk factors

BACKGROUND

Elevated plasma lipoprotein (a) [Lp(a)] and coronary artery calcification (CAC) are established cardiovascular risk factors that correlate with each other. We hypothesized that other cardiovascular risk factors could affect their relationship.

METHODS

We tested for interactions of 24 study variables related to dyslipidemia, diabetes, insulin resistance, hypertension, inflammation and coagulation with baseline Lp(a) on change in CAC volume and density over 9.5 years in 5975 Multi-Ethnic Study of Atherosclerosis (MESA) participants, free of apparent cardiovascular disease at baseline.

RESULTS

Elevated Lp(a) was associated with larger absolute increase in CAC volume (3.21 and 4.45 mm3/year higher for Lp(a) ≥30 versus <30 mg/dL, and Lp(a) ≥50 versus <50 mg/dL, respectively), but not relative change in CAC volume. No association was found with change in CAC density when assessing continuous ln-transformed Lp(a). The association between elevated Lp(a) (≥30 mg/dL) and absolute change in CAC volume was greater in participants with higher circulating levels of interleukin-2 soluble receptor α, soluble tumor necrosis factor alpha receptor 1 and fibrinogen (15.33, 11.81 and 7.02 mm3/year in quartile 4, compared to -3.44, -0.59 and 1.91 mm3/year in quartile 1, respectively). No significant interaction was found for other study variables. Similar interactions were seen when assessing Lp(a) levels ≥50 mg/dL.

CONCLUSIONS

Elevated Lp(a) was associated with an absolute increase in CAC volume, especially in participants with higher levels of selected markers of inflammation and coagulation. These results suggest Lp(a) as a potential biomarker for CAC volume progression.

Aptamers for Proteins Associated with Rheumatic Diseases: Progress, Challenges, and Prospects of Diagnostic and Therapeutic Applications

Nucleic acid aptamers capable of affine and specific binding to their molecular targets have now established themselves as a very promising alternative to monoclonal antibodies for diagnostic and therapeutic applications. Although the main focus in aptamers’ research and development for biomedicine is made on cardiovascular, infectious, and malignant diseases, the use of aptamers as therapeutic or diagnostic tools in the context of rheumatic diseases is no less important. In this review, we consider the main features of aptamers that make them valuable molecular tools for rheumatologists, and summarize the studies on the selection and application of aptamers for protein biomarkers associated with rheumatic diseases. We discuss the progress in the development of aptamer-based diagnostic assays and targeted therapeutics for rheumatic disorders, future prospects in the field, and issues that have yet to be addressed.