Low-Cost Biosensor Technologies for Rapid Detection of COVID-19 and Future Pandemics.

Many systems have been designed for the detection of SARS-CoV-2, which is the virus that causes COVID-19. SARS-CoV-2 is readily transmitted, resulting in the rapid spread of disease in human populations. Frequent testing at the point of care (POC) is a key aspect for controlling outbreaks caused by SARS-CoV-2 and other emerging pathogens, as the early identification of infected individuals can then be followed by appropriate measures of isolation or treatment, maximizing the chances of recovery and preventing infectious spread. Diagnostic tools used for high-frequency testing should be inexpensive, provide a rapid diagnostic response without sophisticated equipment, and be amenable to manufacturing on a large scale. The application of these devices should enable large-scale data collection, help control viral transmission, and prevent disease propagation. Here we review functional nanomaterial-based optical and electrochemical biosensors for accessible POC testing for COVID-19. These biosensors incorporate nanomaterials coupled with paper-based analytical devices and other inexpensive substrates, traditional lateral flow technology (antigen and antibody immunoassays), and innovative biosensing methods. We critically discuss the advantages and disadvantages of nanobiosensor-based approaches compared to widely used technologies such as PCR, ELISA, and LAMP. Moreover, we delineate the main technological, (bio)chemical, translational, and regulatory challenges associated with developing functional and reliable biosensors, which have prevented their translation into the clinic. Finally, we highlight how nanobiosensors, given their unique advantages over existing diagnostic tests, may help in future pandemics.

Rapid and accurate detection of herpes simplex virus type 2 using a low-cost electrochemical biosensor.

Herpes simplex virus type 2 (HSV-2) infection, which is almost exclusively sexually transmitted, causes genital herpes. Although this lifelong and incurable infection is extremely widespread, currently there is no readily available diagnostic device that accurately detects HSV-2 antigens to a satisfactory degree. Here, we report an ultrasensitive electrochemical device that detects HSV-2 antigens within 9 min and costs just $1 (USD) to manufacture. The electrochemical biosensor is biofunctionalized with the human cellular receptor nectin-1 and detects the glycoprotein gD2, which is present within the HSV-2 viral envelope. The performance of the device is tested in a guinea pig model that mimics human biofluids, yielding 88.9% sensitivity, 100.0% specificity, and 95.0% accuracy under these conditions, with a limit of detection of 0.019 fg mL-1 for gD2 protein and 0.057 PFU mL-1 for titered viral samples. Importantly, no cross-reactions with other viruses were detected, indicating the adequate robustness and selectivity of the sensor. Our low-cost technology could facilitate more frequent testing for HSV-2.

A bacterial cellulose-based and low-cost electrochemical biosensor for ultrasensitive detection of SARS-CoV-2.

COVID-19 has led to over 6.8 million deaths worldwide and continues to affect millions of people, primarily in low-income countries and communities with low vaccination coverage. Low-cost and rapid response technologies that enable accurate, frequent testing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are crucial for outbreak prevention and infectious disease control. Here we produce and characterize cellulose fibers naturally generated by the bacterium Gluconacetobacter hansenii as an alternative biodegradable substrate for manufacturing an eco-friendly diagnostic test for COVID-19. Using this green technology, we describe a novel and label-free potentiometric diagnostic test that can detect SARS-CoV-2 within 10 min and costs US$3.50 per unit. The test has bacterial cellulose (BC) as its substrate and a carbon-based electrode modified with graphene oxide and the human angiotensin-converting enzyme-2 (ACE2) as its receptor. Our device accurately and precisely detects emerging SARS-CoV-2 variants and demonstrates exceptional sensitivity, specificity, and accuracy for tested clinical nasopharyngeal/oropharyngeal (NP/OP) samples.

Low-Cost Optodiagnostic for Minute-Time Scale Detection of SARS-CoV-2.

The COVID-19 pandemic has exacerbated our society's tremendous health equity gap. Disadvantaged populations have been disproportionally affected by COVID-19, lacking access to affordable testing, a known effective tool for preventing viral spread, hospitalizations, and deaths. Here, we describe COVID-19 Low-cost Optodiagnostic for Rapid testing (COLOR), a colorimetric biosensor fabricated on cotton swabs using gold nanoparticles modified with human angiotensin-converting enzyme 2 (ACE2), which costs 15¢ to produce and detects SARS-CoV-2 within 5 min. COLOR detected very low viral particle loads (limit of detection: 0.154 pg mL-1 of SARS-CoV-2 spike protein), and its color intensity correlated with the cycle threshold (Ct) values obtained using reverse transcription polymerase chain reaction (RT-PCR). The performance of COLOR was assessed using 100 nasopharyngeal/oropharyngeal (NP/OP) clinical samples, yielding sensitivity, specificity, and accuracy values of 96%, 84%, and 90%, respectively. In summary, each COLOR test can be manufactured for 15¢ and presents rapid minute-time scale detection of SARS-CoV-2, thus providing a solution to enable high-frequency testing, particularly in low-resource communities.

Minute-scale detection of SARS-CoV-2 using a low-cost biosensor composed of pencil graphite electrodes.

COVID-19 has led to over 3.47 million deaths worldwide and continues to devastate primarily middle- and low-income countries. High-frequency testing has been proposed as a potential solution to prevent outbreaks. However, current tests are not sufficiently low-cost, rapid, or scalable to enable broad COVID-19 testing. Here, we describe LEAD (Low-cost Electrochemical Advanced Diagnostic), a diagnostic test that detects severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within 6.5 min and costs $1.50 per unit to produce using easily accessible and commercially available materials. LEAD is highly sensitive toward SARS-CoV-2 spike protein (limit of detection = 229 fg⋅mL-1) and displays an excellent performance profile using clinical saliva (100.0% sensitivity, 100.0% specificity, and 100.0% accuracy) and nasopharyngeal/oropharyngeal (88.7% sensitivity, 86.0% specificity, and 87.4% accuracy) samples. No cross-reactivity was detected with other coronavirus or influenza strains. Importantly, LEAD also successfully diagnosed the highly contagious SARS-CoV-2 B.1.1.7 UK variant. The device presents high reproducibility under all conditions tested and preserves its original sensitivity for 5 d when stored at 4 °C in phosphate-buffered saline. Our low-cost and do-it-yourself technology opens new avenues to facilitate high-frequency testing and access to much-needed diagnostic tests in resource-limited settings and low-income communities.

Low-cost biosensor for rapid detection of SARS-CoV-2 at the point of care.

SARS-CoV-2, the virus that causes COVID-19, has killed over 3 million people worldwide. Despite the urgency of the current pandemic, most available diagnostic methods for COVID-19 use RT-PCR to detect nucleic acid sequences specific to SARS-CoV-2. These tests are limited by their requirement of a large laboratory space, high reagent costs, multistep sample preparation, and the potential for cross-contamination. Moreover, results usually take hours to days to become available. Therefore, fast, reliable, inexpensive, and scalable point-of-care diagnostics are urgently needed. Here, we describe RAPID 1.0, a simple, handheld, and highly sensitive miniaturized biosensor modified with human receptor angiotensin-converting enzyme-2. RAPID 1.0 can detect SARS-CoV-2 using 10 µL of sample within 4 min through its increased resistance to charge transfer of a redox probe measured by electrochemical impedance spectroscopy. The sensitivity and specificity of RAPID for nasopharyngeal/oropharyngeal swab and saliva samples are 85.3% and 100% and 100% and 86.5%, respectively.

Does the political will exist to bring quality-assured and affordable drugs to low- and middle-income countries?

BACKGROUND: Increased coverage with antiretroviral therapy for people living with HIV in low- and middle-income countries has increased their life expectancy associated with non-HIV comorbidities and the need for quality-assured and affordable non-communicable diseases drugs . Funders are leaving many middle-income countries that will have to pay and provide quality-assured and affordable HIV and non-HIV drugs, including for non-communicable diseases. OBJECTIVE: To estimate costs for originator and generic antiretroviral therapy as the number of people living with HIV are projected to increase between 2016 and 2026, and discuss country, regional and global factors associated with increased access to generic drugs. METHODS: Based on estimates of annual demand and prices, annual cost estimates were produced for generic and originator antiretroviral drug prices in low- and middle-income countries and projected for 2016-2026. RESULTS: Drug costs varied between US$1.5 billion and US$4.8 billion for generic drugs and US$ 8.2 billion and US$16.5 billion for originator drugs between 2016 and 2026. DISCUSSION: The global HIV response increased access to affordable generic drugs in low- and middle-income countries. Cheaper active pharmaceutical ingredients and market competition were responsible for reduced drug costs. The development and implementation of regulatory changes at country, regional and global levels, covering intellectual property rights and public health, and flexibilities in patent laws enabled prices to be reduced. These changes have not yet been applied in many low- and middle-income countries for HIV, nor for other infectious and non-communicable diseases, that lack the profile and political attention of HIV. Licensing backed up with Trade-Related Aspects of Intellectual Property Rights safeguards should become the norm to provide quality-assured and affordable drugs within competitive generic markets. CONCLUSION: Does the political will exist among policymakers and other stakeholders to develop and implement these country, regional and global frameworks for non-HIV drugs as they did for antiretroviral drugs?

Developing and implementing national health identifiers in resource limited countries: why, what, who, when and how?

Many resource-limited countries are scaling up health services and health-information systems (HISs). The HIV Cascade framework aims to link treatment services and programs to improve outcomes and impact. It has been adapted to HIV prevention services, other infectious and non-communicable diseases, and programs for specific populations. Where successful, it links the use of health services by individuals across different disease categories, time and space. This allows for the development of longitudinal health records for individuals and de-identified individual level information is used to monitor and evaluate the use, cost, outcome and impact of health services. Contemporary digital technology enables countries to develop and implement integrated HIS to support person centred services, a major aim of the Sustainable Development Goals. The key to link the diverse sources of information together is a national health identifier (NHID). In a country with robust civil protections, this should be given at birth, be unique to the individual, linked to vital registration services and recorded every time that an individual uses health services anywhere in the country: it is more than just a number as it is part of a wider system. Many countries would benefit from practical guidance on developing and implementing NHIDs. Organizations such as ASTM and ISO, describe the technical requirements for the NHID system, but few countries have received little practical guidance. A WHO/UNAIDS stake-holders workshop was held in Geneva, Switzerland in July 2016, to provide a 'road map' for countries and included policy-makers, information and healthcare professionals, and members of civil society. As part of any NHID system, countries need to strengthen and secure the protection of personal health information. While often the technology is available, the solution is not just technical. It requires political will and collaboration among all stakeholders to be successful.

Versatile and on-demand biologics co-production in yeast.

Current limitations to on-demand drug manufacturing can be addressed by technologies that streamline manufacturing processes. Combining the production of two or more drugs into a single batch could not only be useful for research, clinical studies, and urgent therapies but also effective when combination therapies are needed or where resources are scarce. Here we propose strategies to concurrently produce multiple biologics from yeast in single batches by multiplexing strain development, cell culture, separation, and purification. We demonstrate proof-of-concept for three biologics co-production strategies: (i) inducible expression of multiple biologics and control over the ratio between biologic drugs produced together; (ii) consolidated bioprocessing; and (iii) co-expression and co-purification of a mixture of two monoclonal antibodies. We then use these basic strategies to produce drug mixtures as well as to separate drugs. These strategies offer a diverse array of options for on-demand, flexible, low-cost, and decentralized biomanufacturing applications without the need for specialized equipment.

The next generation of antimicrobial peptides (AMPs) as molecular therapeutic tools for the treatment of diseases with social and economic impacts.

Anti-infective drugs have had a key role in the contemporary world, contributing to dramatically decrease mortality rates caused by infectious diseases worldwide. Antimicrobial peptides (AMPs) are multifunctional effectors of the innate immune system of mucosal surfaces and present antimicrobial activity against a range of pathogenic viruses, bacteria, and fungi. However, the discovery and development of new antibacterial drugs is a crucial step to overcome the great challenge posed by the emergence of antibiotic resistance. In this review, we outline recent advances in the development of novel AMPs with improved antimicrobial activities that were achieved through characteristic structural design. In addition, we describe recent progress made to overcome some of the major limitations that have hindered peptide biosynthesis.