Extracellular HMGB1 protein is known to induce inflammatory responses leading to an inflammatory storm. The outbreak of the Severe Acute Respiratory Syndrome COVID-19 due to the SARS-CoV-2 virus has resulted in a huge health concern worldwide. Recent data revealed that plasma/serum HMGB1 levels of patients suffering from inflammation-mediated disorders-such as COVID-19, cancer, and autoimmune disorders-correlate positively with disease severity and vice versa. A late release of HMGB1 in sepsis suggests the existence of a wide therapeutic window for treating sepsis. Rapid and accurate methods for the detection of HMGB1 levels in plasma/serum are, therefore, of great importance for monitoring the occurrence, treatment success, and survival prediction of patients with inflammation-mediated diseases. In this review, we briefly explain the role of HMGB1 in the cell, and particularly the involvement of extracellular HMGB1 (released from the cells) in inflammation-mediated diseases, with an emphasis on COVID-19. The current assays to measure HMGB1 levels in human plasma-Western blotting, ELISA, EMSA, and a new approach based on electrochemical immunosensors, including some of our preliminary results-are presented and thoroughly discussed.

• Keywords
• COVID-19, ELISA, EMSA, HMGB1, immunosensor, plasma/serum,
• MeSH
• Biosensing Techniques MeSH
• COVID-19 * blood   diagnosis   MeSH
• Immunoassay MeSH
• Humans MeSH
• Prognosis MeSH
• HMGB1 Protein * blood   MeSH
• SARS-CoV-2 MeSH
• Sepsis * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• HMGB1 protein, human MeSH Browser
• HMGB1 Protein * MeSH

The ability to detect low concentrations of analytes and in particular low-abundance biomarkers is of fundamental importance, e.g., for early-stage disease diagnosis. The prospect of reaching the ultimate limit of detection has driven the development of single-molecule bioaffinity assays. While many review articles have highlighted the potentials of single-molecule technologies for analytical and diagnostic applications, these technologies are not as widespread in real-world applications as one should expect. This Review provides a theoretical background on single-molecule-or better digital-assays to critically assess their potential compared to traditional analog assays. Selected examples from the literature include bioaffinity assays for the detection of biomolecules such as proteins, nucleic acids, and viruses. The structure of the Review highlights the versatility of optical single-molecule labeling techniques, including enzymatic amplification, molecular labels, and innovative nanomaterials.

• Keywords
• digital assays, immunoassays, optical detection, signal background, single-molecule detection,
• MeSH
• Biomarkers analysis   MeSH
• Enzyme-Linked Immunosorbent Assay MeSH
• Fluorescent Dyes chemistry   MeSH
• Limit of Detection MeSH
• Nanostructures chemistry   MeSH
• Nucleic Acids analysis   MeSH
• Polymerase Chain Reaction methods   MeSH
• Signal-To-Noise Ratio MeSH
• Proteins analysis   MeSH
• Binding Sites MeSH
• Viruses isolation & purification   MeSH
• Single Molecule Imaging methods   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Biomarkers MeSH
• Fluorescent Dyes MeSH
• Nucleic Acids MeSH
• Proteins MeSH