Aptamer-based Emerging Tools for Viral Biomarker Detection: A Focus on SARS-CoV-2.

Viral infections can cause fatal illnesses to humans as well as animals. Early detection of viruses is therefore crucial to provide effective treatment to patients. Recently, the Covid-19 pandemic has undoubtedly given an alarming call to develop rapid and sensitive detection platforms. The viral diagnostic tools need to be fast, affordable, and easy to operate with high sensitivity and specificity equivalent or superior to the currently used diagnostic methods. The present detection methods include direct detection of viral antigens or measuring the response of antibodies to viral infections. However, the sensitivity and quantification of the virus are still a significant challenge. Detection tools employing synthetic binding molecules like aptamers may provide several advantages over the conventional methods that use antibodies in the assay format. Aptamers are highly stable and tailorable molecules and are therefore ideal for detection and chemical sensing applications. This review article discusses various advances made in aptamer-based viral detection platforms, including electrochemical, optical, and colorimetric methods to detect viruses, specifically SARS-Cov-2. Considering the several advantages, aptamers could be game-changing in designing high-throughput biosensors for viruses and other biomedical applications in the future.

Nanoplasmonic biosensors: Theory, structure, design, and review of recent applications.

Nanoplasmonic biosensing shows an immense potential to satisfy the needs of the global health industry - low-cost, fast, and portable automated systems; highly sensitive and real-time detection; multiplexing and miniaturization. In this review, we presented the theory of nanoplasmonic biosensing for popular detection schemes - SPR, LSPR, and EOT - and underline the consideration for nanostructure design, material selection, and their effects on refractometric sensing performance. Later, we covered the bottom-up and top-down nanofabrication methods for nanoplasmonic biosensors. Subsequently, we reviewed the recent examples of nanoplasmonic biosensors over a wide range of clinically relevant analytes in the diagnosis and prognosis of a wide range of diseases and conditions such as biomarker proteins, infectious bacteria, viral agents. Finally, we discussed the challenges of nanoplasmonic biosensing toward clinical translation and proposed strategic avenues to be competitive against current clinical detection methods. Hopefully, nanoplasmonic biosensing can realize its potential through successful demonstrations of clinical translation in the upcoming years.

Nanomaterials to tackle the COVID-19 pandemic.

The rapid worldwide spread of the COVID-19 pandemic, caused by the severe acute respiratory SARS-CoV-2, has created an urgent need for its diagnosis and treatment. As a result, many researchers have sought to find the most efficient and appropriate methods to detect and treat the SARS-CoV-2 virus over the past few months. Real-time reverse-transcriptase polymerase chain reaction (RT-PCR) testing is currently used as one of the most reliable methods to detect the new virus; however, this method is time-consuming, labor-intensive, and requires trained laboratory workers. Moreover, despite its high sensitivity and specificity, false negatives are reported, especially in non-nasopharyngeal swab samples that yield lower viral loads. Therefore, designing and employing faster and more reliable methods seems necessary. In recent years, many attempts have been made to fabricate various nanomaterial-based biosensors to detect viruses and bacteria in clinical samples. The use of nanomaterials plays a significant role in improving the performance of biosensors. Plasmonic biosensors, field-effect transistor (FET)-based biosensors, electrochemical biosensors, and reverse transcription loop-mediated isothermal amplification (RT-LAMP) methods are only some of the effective ways to detect viruses. However, to use these biosensors to detect the SARS-CoV-2 virus, modifications must be performed to increase sensitivity and speed of testing due to the rapidly spreading nature of SARS-CoV-2, which requires an early point of care detection and treatment for pandemic control. Several studies have been carried out to show the nanomaterial-based biosensors' performance and success in detecting the novel virus. The limit of detection, accuracy, selectivity, and detection speed are some vital features that should be considered during the design of the SARS-CoV-2 biosensors. This review summarizes various nanomaterials-based sensor platforms to detect the SARS-CoV-2, and their design, advantages, and limitations.