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Immunosensor for HIV-1 diagnostics based on immobilization of the antigenic peptide p24-3 into liposomes
Insights
This study presents a new immunosensor for diagnosing Human Immunodeficiency Virus type 1 (HIV-1). It uses a peptide from the HIV-1 p24 protein within layer-by-layer films for potential low-cost diagnostics.
Area of Science:
- Biomedical Engineering
- Immunotechnology
- Biosensing
Background:
- Human Immunodeficiency Virus type 1 (HIV-1) diagnosis relies on detecting viral proteins.
- The p24 protein is a key antigen for HIV-1 detection.
- Developing sensitive and cost-effective diagnostic tools remains crucial.
Purpose of the Study:
- To develop a novel immunosensor for HIV-1 diagnostics.
- To utilize the biorecognition between anti-p24 antibody and a specific HIV-1 p24 peptide (p24-3).
- To investigate the immobilization of p24-3 within layer-by-layer (LbL) films for biosensing applications.
Main Methods:
- Encapsulation of p24-3 peptide in phospholipid liposomes.
- Immobilization of liposome-encapsulated p24-3 in polyethyleneimine (PEI) based LbL films.
- Characterization using circular dichroism (CD) spectroscopy and fluorescence spectroscopy.
- Detection of anti-p24 antibody using impedance spectroscopy.
Main Results:
- Circular dichroism confirmed an increase in alpha helix conformation of p24-3 within liposomes.
- Fluorescence emission showed a blue shift, indicating a partially buried tryptophan residue in liposomes and LbL films.
- LbL films successfully preserved the structure of p24-3, enabling recognition of the anti-p24 antibody.
- Impedance spectroscopy demonstrated the potential for antibody detection.
Conclusions:
- Layer-by-layer films incorporating p24-3 peptide are structurally stable.
- The developed immunosensor shows promise for detecting HIV-1.
- This approach may lead to low-cost and user-friendly HIV-1 diagnostic assays.
Abstract:
In this work we developed an immunosensor for HIV-1 diagnostics that exploits the biorecognition between the antibody anti-p24 and the antigenic peptide p24-3 (AMATLRAEQASQEVKNWMTETL- LVQNA) derived from the HIV-1 p24 protein. p24-3 was encapsulated in phospholipid liposomes and immobilized in layer-by-layer (LbL) films produced with polyethyleneimine (PEI). The incorporation of p24-3 into liposomes was investigated using circular dichroism (CD) spectroscopy, from which an increase in the alpha helix conformation could be noted. The maximum fluorescence emission for p24-3 occurred at 340 nm in solution, compatible with the tryptophan residue being exposed to the solvent, and at 335 and 322 nm when in liposomes and PEI/p24-3-liposome LbL films, respectively. This blue shift is consistent with the tryptophan being in a partially buried environment. With the preserved structure in the LbL films, p24-3 could recognize the anti-p24 antibody in impedance spectroscopy measurements. Therefore, LbL films containing p24-3 may be suitable for detecting HIV-1 in a low-cost, easy-to-use immunosensing assay.
