Liquid Crystal Based Binding Assay for Detecting HIV-1 Surface Glycoprotein

Abstract

Surface protein gp-120 of HIV-1 virus plays an important role in the infection of HIV-1, but detection of gp-120 during the early stage of infection is very difficult. Herein, we report a binding bioassay based on an RNA aptamer B40t77, which binds specifically to gp-120. The bioassay is built upon a hydrophobic glass slide with surface immobilized gp-120. When the glass surface is incubated in a solution containing B40t77, the aptamer is able to bind to gp-120 specifically and remove it from the surface after a short incubation time of 30 min. The result of the binding event can be amplified by using liquid crystal (LC) into optical signals in the final step. By using this bioassay, we are able to detect as low as 1 μg/ml of gp-120 with high specificity within 30 min. No response is obtained when gp-120 is replaced by other protein such as bovine serum albumin (BSA). This is the first qualitative bioassay which provides a simple way for the detection of gp-120 with the naked eye. The assay is robust, low-cost and does not require additional labeling. Thus, the bioassay is potentially useful for the early detection of HIV-1 in resources-limited regions.

Aptamer-Based Gold Nanoparticles–PDMS Composite Stamps as a Platform for Micro-Contact Printing

“…Despite of the fact that our proposed limit of detection (LoD) is higher than previously reported, the present biosensing technique is easy to operate, simple and allows detection of gp-120 from the protein mixture. Moreover, compared with our previously reported aptasensors for gp-120 detection [ 21 , 23 ], our present proposed sensing technique not only detects gp-120 from the protein mixture but also transfers the detected gp-120 protein onto a glass substrate for further qualitative analysis.…”

“…Since the inclusion of AuNPs on the PDMS surface makes it a suitable platform for attachment of biorecognition probes (aptamer, proteins or antibodies) with thiol modification [ 11 , 14 , 19 ], we propose this composite as a stamp material for attachment of a thiol-modified aptamer based on gold-thiol chemistry, which selectively binds with its target protein, and then transferring of target protein on the desired substrate through μCP. At the same time, aptamers are synthetic single-stranded oligonucleotides (RNA or DNA) that have been exploited as biorecognition probes in various bioassays due to their high specificity and selectivity [ 20 , 21 , 22 , 23 ]. In this study, we chose the B40t77 RNA aptamer as a biorecognition probe for HIV-1 surface glycoprotein gp-120.…”

“…Initially, it was created for HIV-1 therapeutics [ 24 ]. We have recently used the B40t77 aptamer to develop bioassays for gp-120 [ 21 , 23 ]. The key steps involved in μCP are: (1) fabrication of PDMS stamps; (2) in situ synthesis of gold nanoparticles on the surface of an as-prepared PDMS stamp; (3) linking the stamp with a thiol-modified aptamer and incubating these stamps with the target protein before μCP; and (4) conformal contact of aptamer-conjugated AuNPs–PDMS stamps with the UV treated DMOAP-coated glass slide.…”

Liquid Crystal Biosensors: A New Therapeutic Window to Point-of-Care Diagnostics

“…At very low bacterial cell densities (minimum 500 cell mL –1 ), lipopolysaccharide (LPS) in combination with an LC-based sensor may detect the presence of bacteria, regardless of their viability (maximum 15 min) . Yang et al employed an LC-based binding bioassay to detect the surface protein of the HIV-1 virus by using the RNA aptamer B40t77 for specific binding with gp-120 …”

State-of-the-Art Development in Liquid Crystal Biochemical Sensors

“…They formed a binding assay on the glass surface that was amplified into an optical signal by LC. This high specific gp-120 detection technique had LOD at 1 µg/mL, offering potential in early stage HIV-1 detection [ 122 ].…”