Immunosensor for HIV-1 Diagnostics Based on Immobilization of the Antigenic Peptide p24-3 Into Liposomes

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.

Analysis of Scanning Electron Microscopy Images To Investigate Adsorption Processes Responsible for Detection of Cancer Biomarkers

“…The concentration of a biomarker away from a reference level is an important indicator to diagnose pathogenic processes or a pharmacological response to monitor after a therapeutic intervention . Various detection methods and types of biosensors have been used to detect an equally wide variety of biomarkers, , including electrochemical biosensors. − The performance of these biosensors depends on the way nanomaterials and biomolecules are combined, and therefore control of film architecture is essential, which is normally achieved using techniques such as Langmuir–Blodgett (LB), layer-by-layer (LbL), and self-assembled monolayers (SAMs). − The concept of nanoarchitectonics has been introduced because biosensors must be designed in order to minimize denaturing of the biomolecules and enhance the sensitivity and selectivity. A common feature in these biosensors is that their selectivity is ascribed to the presence of very specific interactions between the biomolecule immobilized in the biosensor, such as an antibody or antigen, and the analyte – which would be the corresponding antigen or antibody.…”

Liposome-Encapsulated Biomolecules: Application in Enzymatic Biosensors and Immunosensors

“…Quando essas moléculas atingem este estágio, a monocamada é transferida para um substrato através da sua imersão e retirado da subfase aquosa. 39 [47][48][49][50] Devido à afinidade, biocompatibilidade com os tecidos e células do organismo e capacidade de incorporar e estabilizar biomoléculas e fármacos tanto hidrossolúveis como lipossolúveis, os lipossomos são vantajosos para aplicação na área médica e farmacêutica, como por exemplo, carreadores de fármacos para células alvo. 51,52 Os lipossomos imobilizados em superfícies sólidas também estão sendo explorado para liberação de fármacos 53 e para estabilização de biomoléculas em biossensores, 1,5 neste último, a estabilização ajuda a manter a atividade biológica e, consequentemente, melhora a seletividade e sensibilidade dos dispositivos.…”

“…54,60 A molécula do anticorpo também apresenta uma estrutura basal, uma região vertical denominada Fc porque seu fragmento se cristaliza com facilidade quando o anticorpo sofre hidrólise, esta região não interage com o antígeno e, portanto, possibilita a imobilização do mesmos nos transdutores sem comprometer a sua especificidade. 54 49 combinou a técnica camada por camada (LbL) e a encapsulação do peptídeo antigênico p24-3 (derivado da proteína p24 do HIV-1) em lipossomos e desenvolveu um imunossensor para a detecção do HIV-1. A conformação do p24-3 encapsulado foi analisado por dicroísmo circular (CD), no qual observou-se um au e to da o fo ação de est utu as α-hélice e consequentemente obteve-se uma melhora na detecção.…”

Where Chemical Sensors May Assist in Clinical Diagnosis Exploring “Big Data”

“…For example, the strategy adopted in the interactive document map technique (IDMAP) 29 has proven successful in several cases, such as in enhancing the performance of biosensors to detect HIV antibodies. 30 The cost function in IDMAP is defined as:…”