A Portable Biosensor Based on Au Nanoflower Interface Combined with Electrochemical Immunochromatography for POC Detection of Prostate-Specific Antigen

The LOD paradox: When lower isn't always better in biosensor research and development

Biosensor research has long focused on achieving the lowest possible Limits of Detection (LOD), driving significant advances in sensitivity and opening up new possibilities in analysis. However, this intense focus on low LODs may not always meet the practical needs or suit the actual uses of these devices. While technological improvements are impressive, they can sometimes overlook important factors such as detection range, ease of use, and market readiness, which are vital for biosensors to be effective in real-world applications. This review advocates for a balanced approach to biosensor development, emphasizing the need to align technological advancements with practical utility. We delve into various applications, including the detection of cancer biomarkers, pathology-related biomarkers, and illicit drugs, illustrating the critical role of LOD within these contexts. By considering clinical needs and broader design aspects like cost-effectiveness, sustainability, and regulatory compliance, we argue that integrating technical progress with practicality will enhance the impact of biosensors. Such an approach ensures that biosensors are not only technically sound but also widely useable and beneficial in real-world applications. Addressing the diverse analytical parameters alongside user expectations and market demands will likely maximize the real-world impact of biosensors.

Controlled silver electrodeposition on gold nanoparticle antibody tags for ultrasensitive prostate specific antigen sensing using electrochemical and optical smartphone detection

One of the current challenges in medicine is to achieve a rapid and unequivocal detection and quantification of extremely low levels of disease biomarkers in complex biological samples. Here, we present the development and analytical evaluation of a low-cost smartphone-based system designed for ultrasensitive detection of the prostate-specific antigen (PSA) using two detection alternatives: electrochemical or optical, by coupling the smartphone with a portable potentiostat or magnifying lenses. An antibody tagged with gold nanoparticles (AuNPs), and indium tin oxide coated polyethylene terephthalate platform (ITO-PET) have been used to develop a sandwich-type immunoassay. Then, a controlled silver electrodeposition on the AuNPs surface is carried out, enhancing their size greatly. Due to such strong nanoparticle-size amplification (from nm to μm), the final detection can be dual, by measuring current intensity or the number of silver-enlarged microstructures generated. The proposed strategies exhibited limit detections (LOD) of 102 and 37 fg/mL for electrochemical and optical detection respectively. The developed immunosensor reaches excellent selectivity and performance characteristics to quantify biomarkers at clinically relevant values without any pretreatment. These proposed procedures could be useful to check and verify possible recurrence after clinical treatment of tumors or even report levels of disease serum biomarkers in early stages.

Electrochemical Biosensor for Point-of-Care Testing of Low-Abundance Biomarkers of Neurological Diseases

The neurofilament protein light chain (NEFL) is a potential biomarker of neurodegenerative diseases, and interleukin-6 (IL-6) is also closely related to neuroinflammation. Especially, NEFL and IL-6 are the two most low-abundance known protein markers of neurological diseases, making their detection very important for the early diagnosis and prognosis prediction of such kinds of diseases. Nevertheless, quantitative detection of low concentrations of NEFL and IL-6 in serum remains quite difficult, especially in the point-of-care test (POCT). Herein, we developed a portable, sensitive electrochemical biosensor combined with smartphones that can be applied to multiple scenarios for the quantitative detection of NEFL and IL-6, meeting the need of the POCT. We used a double-antibody sandwich configuration combined with polyenzyme-catalyzed signal amplification to improve the sensitivity of the biosensor for the detection of NEFL and IL-6 in sera. We could detect NEFL as low as 5.22 pg/mL and IL-6 as low as 3.69 pg/mL of 6 μL of serum within 2 h, demonstrating that this electrochemical biosensor worked well with serum systems. Results also showed its superior detection capabilities over those of high-sensitivity ELISA for serum samples. Importantly, by detecting NEFL and IL-6 in sera, the biosensor showed its potential for the POCT model detection of all known biomarkers of neurological diseases, making it possible for the mass screening of patients with neurodegenerative diseases.

Point-of-Care Prostate Specific Antigen Testing: Examining Translational Progress toward Clinical Implementation

Prostate cancer (PCa) is the second most common male cancer and is attributable to over 375,000 deaths annually. Prostate specific antigen (PSA) is a key biomarker for PCa and therefore measuring patient PSA levels is an important aspect of the diagnostic pathway. Automated immunoassays are currently utilized for PSA analysis, but they require a laboratory setting with specialized equipment and trained personnel. This results in high diagnostic costs, extended therapeutic turnaround times, and restrictions on testing capabilities in resource-limited settings. Consequently, there is a strong drive to develop point-of-care (PoC) PSA tests that can offer accurate, low-cost, and rapid results at the time and place of the patient. However, many emerging PoC tests experience a trade-off between accuracy, affordability, and accessibility which distinctly limits their translational potential. This review comprehensively assesses the translational advantages and limitations of emerging laboratory-level and commercial PoC tests for PSA determination. Electrochemical and optical PSA sensors from 2013 to 2023 are systematically examined. Furthermore, we suggest how the translational potential of emerging tests can be optimized to achieve clinical implementation and thus improve PCa diagnosis globally.

Recent Advances in Aptamer-Based Sensors for Sensitive Detection of Neurotransmitters

In recent years, there has been an increased demand for highly sensitive and selective biosensors for neurotransmitters, owing to advancements in science and technology. Real-time sensing is crucial for effective prevention of neurological and cardiovascular diseases. In this review, we summarise the latest progress in aptamer-based biosensor technology, which offers the aforementioned advantages. Our focus is on various biomaterials utilised to ensure the optimal performance and high selectivity of aptamer-based biosensors. Overall, this review aims to further aptamer-based biosensor technology.

Label-Free Electrochemical Biosensor Platforms for Cancer Diagnosis: Recent Achievements and Challenges

With its fatal effects, cancer is still one of the most important diseases of today's world. The underlying fact behind this scenario is most probably due to its late diagnosis. That is why the necessity for the detection of different cancer types is obvious. Cancer studies including cancer diagnosis and therapy have been one of the most laborious tasks. Since its early detection significantly affects the following therapy steps, cancer diagnosis is very important. Despite researchers' best efforts, the accurate and rapid diagnosis of cancer is still challenging and difficult to investigate. It is known that electrochemical techniques have been successfully adapted into the cancer diagnosis field. Electrochemical sensor platforms that are brought together with the excellent selectivity of biosensing elements, such as nucleic acids, aptamers or antibodies, have put forth very successful outputs. One of the remarkable achievements of these biomolecule-attached sensors is their lack of need for additional labeling steps, which bring extra burdens such as interference effects or demanding modification protocols. In this review, we aim to outline label-free cancer diagnosis platforms that use electrochemical methods to acquire signals. The classification of the sensing platforms is generally presented according to their recognition element, and the most recent achievements by using these attractive sensing substrates are described in detail. In addition, the current challenges are discussed.

Recent Advancements in Electrochemical Biosensors for Monitoring the Water Quality

The release of chemicals and microorganisms from various sources, such as industry, agriculture, animal farming, wastewater treatment plants, and flooding, into water systems have caused water pollution in several parts of our world, endangering aquatic ecosystems and individual health. World Health Organization (WHO) has introduced strict standards for the maximum concentration limits for nutrients and chemicals in drinking water, surface water, and groundwater. It is crucial to have rapid, sensitive, and reliable analytical detection systems to monitor the pollution level regularly and meet the standard limit. Electrochemical biosensors are advantageous analytical devices or tools that convert a bio-signal by biorecognition elements into a significant electrical response. Thanks to the micro/nano fabrication techniques, electrochemical biosensors for sensitive, continuous, and real-time detection have attracted increasing attention among researchers and users worldwide. These devices take advantage of easy operation, portability, and rapid response. They can also be miniaturized, have a long-life span and a quick response time, and possess high sensitivity and selectivity and can be considered as portable biosensing assays. They are of special importance due to their great advantages such as affordability, simplicity, portability, and ability to detect at on-site. This review paper is concerned with the basic concepts of electrochemical biosensors and their applications in various water quality monitoring, such as inorganic chemicals, nutrients, microorganisms' pollution, and organic pollutants, especially for developing real-time/online detection systems. The basic concepts of electrochemical biosensors, different surface modification techniques, bio-recognition elements (BRE), detection methods, and specific real-time water quality monitoring applications are reviewed thoroughly in this article.