Aptamer–17β‐estradiol–antibody sandwich ELISA for determination of gynecological endocrine function

Prepared Sandwich structure WS2/ag@MIP composite for ultrasensitive SERS detection of trace 17β-estradiol in food

17β-E2 is used in animal growth regulation and agricultural fertilizer, and even ng L-1 mass concentration levels can show biological effects. In this work, Ag NPs was used as surface-enhanced Raman spectroscopy (SERS) source and WS2 was synthesized by a simple method to provide a uniform distribution platform for Ag NPs. The MIP was the shell, which can selectively enrich the target molecule, pull the distance between the target molecule and SERS source, and protect Ag NPs. A cyclable SERS substrate with high sensitivity for detecting 17β-E2 in food was constructed. The optimized WS2/Ag@MIP as SERS substrate has the advantages of high Enhanced Factor (EF = 2.78 × 109), low detection limit (LOD = 0. 0958 pM), strong anti-interference ability, and good recycling performance. Moreover, the detection of 17β-E2 in real samples still has good accuracy. This work provides a new possibility for the trace detection of 17β-E2 in food.

High sensitive aptasensing chronic myeloid leukemia on circular electrode-modified by single-walled carbon nanotube

Chronic myeloid leukemia (CML) is a cancer in the bone marrow caused by the proliferation of granulocyte cells at all the maturation stages. Late diagnosis of CML decreases the patient survival rate, makes diagnosing CML is mandatory before entering the blastic phase. CD 19 is an important target for CML and is effectively utilized for therapeutic and diagnosis purposes. This research was focused on developing an aptamer-mediated circular interdigitated electrode (IDE) sensor for detecting the level of CD 19 and measured at 0-2 V with the step of 0.1 V. To improve the surface functionalization on IDE, the surface of IDE was modified with a single-walled carbon nanotube (SWCN) to enhance the aptamer immobilization. SWCN increased the aptamer attachment and also enhanced the analytical performances on IDE. This SWCN-aptamer modified IDE detected the CD 19 as low as 10 nM on a linear co-regression range from 10 to 100 nM [y = 2.0126x - 2.3857; R2 = 0.9749]. Furthermore, control performances with CD 33, and complementary aptamer did not show the increment of current, and CD 19 spiked human serum increased the current flow without significant interference, demonstrating the specific and selective detection of CD 19. This biosensor quantifies CD 19 biomarker at its lower level and diagnoses CML and its associated complications.

Gold-antibody-aptamer complexed electrochemical sensing surface for septic arthritis biomarker determination

Septic arthritis (SA) is more severe in patients with rheumatoid arthritis, joint surgical issues, or a weakened immune system. Timely diagnosis of SA is crucial for effective treatment. Traditional diagnostic methods such as ELISA, white blood cell counting, blood culture, qPCR, and imaging techniques are often less accurate and time-consuming. Researchers are focusing on developing highly sensitive biosensors for SA using blood-based biomarkers. Procalcitonin is a protein and a well-established biomarker for SA. This research focuses on developing a procalcitonin interdigitated electrode (IDE) biosensor using a probe made of an aptamer and antibody-modified gold nanoparticle (AuNP) complex. The probe was attached to the IDE through an amine linker and then interacted with procalcitonin. AuNPs increased the attachment of the aptamer and antibody to the IDE, enabling the detection of procalcitonin at levels as low as 10 ng/mL, with a linear regression curve ranging from 10 to 100 ng/mL [y = 4.0691x - 2.1887; R2 = 0.9937]. Furthermore, procalcitonin-spiked serum elevated the current level with increasing procalcitonin concentrations, while control performances did not enhance the current, indicating the selective and specific detection of procalcitonin. This AuNP-aptamer-antibody complexed biosensor effectively identifies procalcitonin at low levels and aids in the diagnosis of SA.

Sensitive osteoarthritis sensing by salt-induced aggregation and dispersion of gold nanoparticles

Osteoarthritis occurs in any joints, and identification in its earlier stages helps to treat the disease and increase the recovery rate. The radiography method and imaging techniques are traditionally used to identify osteoarthritis. But these methods are expensive, and with the complicated steps. Researchers are working toward developing a highly sensitive biosensor in identifying the osteoarthritis biomarker. This research was focused on developing a C-terminal telopeptide of type II collagen (CTX-II) colorimetric sensor with gold nanoparticle (AuNP) for diagnosing osteoarthritis. Anti-CTX-II was conjugated with AuNP and then added with CTX-II and sodium chloride for the color change. In the presence of CTX-II, antibody releases from AuNP then binds with CTX-II, and the color of AuNP changed to purple. Without the CTX-II, AuNP remains its red color (dispersed). This easier colorimetric assay detected the CTX-II as low as 2 ng/mL on linear regression [y = 0.0131x - 0.0051; R2 = 0.9205]. Furthermore, control performances with the relevant proteins osteopontin, IL-6, and nonimmune antibody failed to change the color confirming the specific identification of CTX-II.

High-sensitivity immunoassay on interdigitated electrode to detect osteoporosis biological marker

Osteoporosis is with porous bones, which refers to a decrease in the bone mineral density and weakens the bones to become brittle. Osteoporosis often progresses without any pain or symptoms until the bone fractures. Monitoring the condition of bone regularly helps to identify the bone that weakens at its earlier stages. In general, radiological techniques have been used to measure bone mineral density, are expensive, and the procedures are complicated. Therefore, researchers are focusing on the alternative method of biomarker quantification to identify bone mineral density. This research work was focused on quantifying the osteoporosis biomarker of C-terminal telopeptide of type I collagen (CTX-I) on an interdigitated electrode (IDE) sensor. Gold nanomaterial-modified anti-CTX-I antibody was attached to silica nanomaterial-decorated IDE and then identified by CTX-I interaction. Higher immobilization of antibodies was recorded on diamond-modified IDE through gold nanoparticles, and detected CTX-I as low as 0.5 pg/mL [y = 1.5507x - 0.9043 R2 = 0.9715], determined on a linear curve at the range 0.5-3.5 ng/mL. Further, specific identification of CTX-I was confirmed by control performances with osteopontin, IL-6, and anti-IgG antibody.

17β-estradiol biosensors based on different bioreceptors and their applications

17β-Estradiol (E2) is a critical sex steroid hormone, which has significant effects on the endocrine systems of both humans and animals. E2 is also believed to play neurotrophic and neuroprotective roles in the brain. Biosensors present a powerful tool to detect E2 because of their small, efficient, and flexible design. Furthermore, Biosensors can quickly and accurately obtain detection results with only a small sampling amount, which greatly meets the detection of the environment, food safety, medicine safety, and human body. This review focuses on previous studies of biosensors for detecting E2 and divides them into non-biometric sensors, enzyme biosensors, antibody biosensors, and aptamer biosensors according to different bioreceptors. The advantages, disadvantages, and design points of various bioreceptors for E2 detection are analyzed and summarized. Additionally, applications of different bioreceptors of E2 detection are presented and highlight the field of environmental monitoring, food and medicine safety, and disease detection in recent years. Finally, the development of E2 detection by biosensor is prospected.

Highly sensitive colorimetric aptasensor for 17β-estradiol detection in milk based on the repetitive-loop aptamer

Trace of 17β-estradiol (E2) contamination in food has been a concern for its negative impacts on human health, leading to the need for an E2-monitoring system. This work reported a new simple, sensitive, and colorimetric E2 detection based on the designed repetitive-loop aptamer and gold nanoparticles (AuNPs). The designed aptamers (L2-L5) exhibited a higher binding capability to E2 than the original truncated aptamer (L1). Although L3-L5 aptamers exhibited the highest binding capability, only L3-aptasensor demonstrated the sensitive detection of E2 in a range of 0.05-0.8 nM, with the limit of detection at 13.1 pM. The developed L3-aptasensor was 7.7-folds more sensitive for E2 detection than the L1-aptasensor. It selectively detected E2, but not the other tested chemicals with similar structures: progesterone, genistein, diethylstilbestrol, bisphenol A, and chloramphenicol. The L3-aptasensor efficiently detected E2 spiked in milk samples within the precision acceptance criterion of recovery rates (100.1%-113.0%) and the relative standard deviations (5.24%-11.06%). These results demonstrated the development of a new aptasensor based on the designed repetitive-loop aptamer that could enhance E2-detection sensitivity and be potentially used for detecting E2 in milk samples with high accuracy and reliability.

Development of DNA aptamer selection approach based on membrane ultrafiltration of aptamer/target complex

Background. Aptamers are small single-stranded DNA or RNA molecules that have an affinity for a specific target molecule. The main method of aptamers construction is the technology of systematic evolution of ligands with exponential enrichment (SELEX). However, the exact approach depends on the nature of target molecules, and is selected and optimized by each researcher independently. The article describes the technique of production of aptamers to the tick-borne encephalitis virus (TBEV) using membrane ultrafiltration with a molecular weight cut-off of 100 kDa. As a result, the pool of aptamers with observable affinity for TBEV is successfully selected and enriched.The aim. To develop the technique suitable for selection of specific DNA aptamers to a live, crude TBEV suspension directly in cell culture supernatant.Materials and methods. The selection of aptamers was carried out using a modified SELEX DNA aptamer technology in combination with semipermeable membrane ultrafiltration using Vivaspin 6 (Sartorius, Germany) concentrators of molecular weight cut-off of 100 kDa. Enrichment of a specific pool of aptamers was performed using real time polymerase chain reaction. Aptamers were sequenced with automated Sanger sequencing method. The direct virucidal effect of the aptamers was determined by the decrease in the titer of the infectious virus after incubation with the aptamer.Results. The pool of aptamers to TBEV was selected and enriched. This aptamer pool expressed affinity both to the infectious TBEV and to the TBEV antigen. Sixteen aptamers were sequenced from this pool and four of them were synthesized and tested for antiviral activity against TBEV. No antiviral activity was observed.Conclusions. The technique developed that can be successfully used to select aptamers to a live virus culture for the viruses comparable in size to TBEV or larger.

Unveiling the underpinnings of various non-conventional ELISA variants: a review article

INTRODUCTION

Enzyme-linked immunosorbent assay (ELISA) is a key bio-analytical technique used for the detection of a large array of antigenic substances of scientific, clinical, food safety, and environmental importance. The assay primarily involves capturing and detecting target analytes using specific antigen-antibody interactions. The wide usage of ELISA shoulders on its high specificity and reproducibility. Notwithstanding, the conventional microwell plate-based format of ELISA has some major drawbacks, such as long assay time (4 - 18 h), large sample volumes requirement (100 - 200 μL), lack of multiplicity, and burdensome procedures that limit its utility in rapid and affordable diagnostics.

AREAS COVERED

Here, we reviewed microfluidic-ELISA, paper-ELISA, aptamer-ELISA, and those based on novel incubation such as heat-ELISA, pressure-ELISA, microwave-ELISA, and sound-ELISA. Further, the current trends and future prospects of these ELISA protocols in clinical diagnostics are discussed.

EXPERT OPINION

The reviewed non-conventional ELISA formats are relatively rapid, require low reagent volumes, are multiplexable, and could be performed in a low-cost setup. In our opinion, these non-conventional variants of ELISA are on a par with the conventional format for clinical diagnostics and fundamental biological research and hold added clinical translational potential for quick, inexpensive, and convenient measurements.

Biomaterials and advanced technologies for the evaluation and treatment of ovarian aging

Ovarian aging is characterized by a progressive decline in ovarian function. With the increase in life expectancy worldwide, ovarian aging has gradually become a key health problem among women. Over the years, various strategies have been developed to preserve fertility in women, while there are currently no clinical treatments to delay ovarian aging. Recently, advances in biomaterials and technologies, such as three-dimensional (3D) printing and microfluidics for the encapsulation of follicles and nanoparticles as delivery systems for drugs, have shown potential to be translational strategies for ovarian aging. This review introduces the research progress on the mechanisms underlying ovarian aging, and summarizes the current state of biomaterials in the evaluation and treatment of ovarian aging, including safety, potential applications, future directions and difficulties in translation.

Vanadium Disulfide Nanosheet Boosts Optical Signal Brightness as a Superior Enzyme Label to Improve the Sensitivity of Lateral Flow Immunoassay

The color-enzyme lateral flow immunoassay (LFIA) has attracted widespread attention to expand the detection range and improve sensitivity via amplifying the color signal after catalyzing the substrate. As a kind of layered transition-metal dichalcogenide (TMD), the vanadium disulfide nanosheet (VS₂NS) possesses superior peroxidase-like catalytic activity. Here, a VS₂NS was applied as an enzyme label in the LFIA to detect 17β-estradiol (E2). Compared to natural horseradish peroxidase, the VS₂NS expresses a more prominent enzyme catalytic performance, stability, and adsorption ability. Under optimal conditions, the calculated limit of detection (cLOD) of the VS₂NS-based LFIA is 0.065 ng mL^-1 for E2, which is sixfold lower than that of the optimized colloidal nanoparticle-based LFIA (cLOD = 0.406 ng mL^-1). Besides, the detection linear range of the VS₂NS-based LFIA can be widened by 1.5 times after the catalytic reaction. Moreover, the VS₂NS-based LFIA exhibits excellent practicability in real sample detection. Simultaneously, this study helps open up the application of the VS₂NS in the trace analysis of LFIAs, which can broaden TMDs' scope of application and better show their properties of color enzymes.

17β-estradiol induces temozolomide resistance through NRF2-mediated redox homeostasis in glioblastoma

Glioblastoma multiforme (GBM) is the most fatal cancer among brain tumors, and the standard treatment of GBM patients is surgical tumor resection followed by radiotherapy and temozolomide (TMZ) chemotherapy. However, tumors always recur due to the developing drug resistance. It has been shown that neurosteroids, including dehydroepiandrosterone and 17β-estradiol, are synthesized in TMZ-resistant GBM tumors. Therefore, we sought to explore the possible role of 17β-estradiol in the development of drug resistance in GBM. Bioinformatics analysis revealed that aromatase/cytochrome P450 19A1 expression was gradually increased in the development from normal, astrocytoma to GBM. The level of 17β-estradiol was significantly increased in TMZ-resistant cells characterized by ultra performance liquid chromatography-tandem mass spectrometry. Furthermore, 17β-estradiol attenuated TMZ-induced cell death and reduced reactive oxygen species production by mitochondria. In addition, 17β-estradiol attenuated oxidative stress by increasing the expression of superoxide dismutase 1/2, catalase, and nuclear factor erythroid 2-related factor (NRF) 2. We found that NRF2 expression was essential for the induction of drug resistance by 17β-estradiol through the reduction of oxidative stress in GBM.

Recent Advances in Aptamer Sensors

Recently, aptamers have attracted attention in the biosensing field as signal recognition elements because of their high binding affinity toward specific targets such as proteins, cells, small molecules, and even metal ions, antibodies for which are difficult to obtain. Aptamers are single oligonucleotides generated by in vitro selection mechanisms via the systematic evolution of ligand exponential enrichment (SELEX) process. In addition to their high binding affinity, aptamers can be easily functionalized and engineered, providing several signaling modes such as colorimetric, fluorometric, and electrochemical, in what are known as aptasensors. In this review, recent advances in aptasensors as powerful biosensor probes that could be used in different fields, including environmental monitoring, clinical diagnosis, and drug monitoring, are described. Advances in aptamer-based colorimetric, fluorometric, and electrochemical aptasensing with their advantages and disadvantages are summarized and critically discussed. Additionally, future prospects are pointed out to facilitate the development of aptasensor technology for different targets.