Increasing the Assembly Efficacy of Peptidic β-Sheets for a Highly-Sensitive HIV Detection

Abstract

Our recent publication illustrates the critical role of phenylalanine-mediated aromatic−aromatic interactions in determining the assembly of peptidic β-sheets. However, the effect of phenylalanine number on regulating the assembly efficacy of peptidic β-sheets remains poorly understood. We herein evaluate the assembly efficacy of β-sheets of a series of oligopeptides which contain 0, 1, 2, or 3 phenylalanine in their molecular backbones. In our assembly system, two phenylalanine (2F) is the minimum number for driving the assembly of β-sheets of oligopeptides. Oligopeptides with three phenylalanine (3F) show significantly increased assembly efficacy of β-sheets compared to that with 2F. These results suggest a positive correlation between the phenylalanine number and assembly efficacy of β-sheets. By improving the assembly efficacy of β-sheets, we further develop a highly sensitive HIV analytical system in which the specific binding of β-sheets with Congo Red induces enhanced fluorescence. For HIV p24 detection, the 3F-based analytical system (0.61 pg/mL) shows a significantly lower limit of detection (LOD) than the 2F-based analytical system (2.44 pg/mL), both of which are more sensitive than commercial ELISA (5 pg/mL) used in the clinic. This work not only illustrates the effect of phenylalanine number on regulating the assembly efficacy of β-sheets but also provides a guideline for the construction of a highly sensitive analytical system of disease diagnosis.

Combining Bioorthogonal Chemistry with Fluorescent Silica Nanoparticles for the Ultrasensitive Detection of the HIV-1 p24 Antigen

“…Since HIV can be transmitted via mother’s milk, it is quite conceivable that HIV– infants could become HIV+ if milk from an HIV+ mother is given to the infant . (ii) Virus concentration monitoring for HIV+ individuals at home or in low-resource settings since most physicians recommend changing the medication if there is a viral rebound to >1000 virus particles/mL (or 4 fM or 0.1 pg/mL of p24) of blood. , Reports of ultrasensitive laboratory-based assays to detect femtomolar concentrations of p24 have been published. − Commercial lateral flow assays, although inexpensive, are limited in scope for early detection or virus concentration monitoring as they cannot detect <1000 virus particles/mL. As a first step toward the development of ultrasensitive POC assays for early detection and viral monitoring, we developed assays to meet the desired femtomolar limits of detection (LODs) for p24 using dye-encapsulated fluorescent silica nanoparticles and bioorthogonal chemistries.…”