Periodic Reporting for period 1 - PREMOTHER (PREvention of MOther-to-child Transmission of HIV and Syphilis using an Electrochemical Readout based on DNA Switches)
Berichtszeitraum: 2019-01-07 bis 2021-01-06
Mother-to-child transmission of HIV and Syphilis causes approximately 305,000 fetal and neonatal deaths every year and leaves 215,000 infants at increased risk of dying from prematurity, low-birth-weight or congenital disease. An accurate diagnosis and a simple treatment during the first weeks of pregnancy could prevent the majority of those deaths. The PREMOTHER project aims at the development of a new technique to be used to precisely measure anti-HIV and anti-syphilis antibodies directly in whole blood, overcoming the intrinsic limitations of current laboratory-based (e.g. expensive, time-consuming) and point-of-care (e.g. qualitative, with low sensitivity and specificity) techniques. As a result, the final device should be able to provide the single-step, quantitative measurement of multiple diagnostic antibodies in less than 15 minutes, thus supporting its use at the point of care by non-specialized personnel. During the timeframe of the project several efforts towards the development of the final device have been made, however due to the year-long limitations related to the COVID-19 pandemic it has not been possible to clinically validate the performance of the device. We expect to conclude such validation in the following months as soon as the pandemic is under control. We believe that, in a near future, this new technology can be a valuable tool towards bringing personalized medicine to both high- and low-income countries.
During the timeframe of the PREMOTHER project, the researcher followed the workplan defined in the project agreement. Specifically, during the first four months he trained on the use of the wax-printing membrane technique and the DNA switch electrochemical sensor. The former allows the fabrication of graphene-based electrodes in a simple and low-cost fashion ideal for point-of-care applications. The latter is a technique that allows the quantitative measurements of antibodies directly in whole blood in less than 15 minutes and requiring just a single step, thus ideal for non-specialized users.
Following the initial training period the researcher worked on the integration of novel bioreceptors into the DNA switch electrochemical sensor. Specifically he selected four HIV-related and four syphilis-related antigens/epitopes. Regarding the HIV-related ones, one peptide from gp41, two linear peptides from p24 and the full soluble portion of p24 were selected for clinical validation. For the syphilis-related ones, since limited bibliography was available describing the immunogenicity of linear peptides, a bioinformatic analysis was performed, resulting in three putative immunogenic peptides and cardiolipin. However the conjugation of the cardiolipin to the DNA switch was not possible and the clinical validation of the epitopes was put on hold due to the restricted use of the clinical laboratory to just COVID-19-related works.
The other part of the PREMOTHER project consisted in the integration of the DNA switch into a graphene-based electrode. In order to do this the functionalization of both reduced graphene oxide and cyanographene were tested. The former following the EDC-sNHS chemistry, while the latter using a dithiol bond formation. Considering the extremely low conductivity of the cyanographene, the reduced graphene oxide was selected. However the strong, non-specific adsorption of the DNA switch on the graphene surface prevented the hybridization of the complementary strand essential to present the antigen/epitope. In response the use of carbon-based ink mixed with gold nanoparticles and commercial screen printed electrodes provided alternative platforms to support the DNA switch electrochemical sensor.
During the PREMOTHER project several scientific and public dissemination activities were carried out. Regarding the former, the researcher presented at two international scientific conferences, authored two peer-reviewed manuscripts (plus other in preparation) and establishing collaboration with clinical and scientific partners. Regarding the latter, the researcher engaged with both university and elementary school students, took part to an online discussion about serological tests and prepared PREMOTHER-dedicated webpage and flyers.
Following the initial training period the researcher worked on the integration of novel bioreceptors into the DNA switch electrochemical sensor. Specifically he selected four HIV-related and four syphilis-related antigens/epitopes. Regarding the HIV-related ones, one peptide from gp41, two linear peptides from p24 and the full soluble portion of p24 were selected for clinical validation. For the syphilis-related ones, since limited bibliography was available describing the immunogenicity of linear peptides, a bioinformatic analysis was performed, resulting in three putative immunogenic peptides and cardiolipin. However the conjugation of the cardiolipin to the DNA switch was not possible and the clinical validation of the epitopes was put on hold due to the restricted use of the clinical laboratory to just COVID-19-related works.
The other part of the PREMOTHER project consisted in the integration of the DNA switch into a graphene-based electrode. In order to do this the functionalization of both reduced graphene oxide and cyanographene were tested. The former following the EDC-sNHS chemistry, while the latter using a dithiol bond formation. Considering the extremely low conductivity of the cyanographene, the reduced graphene oxide was selected. However the strong, non-specific adsorption of the DNA switch on the graphene surface prevented the hybridization of the complementary strand essential to present the antigen/epitope. In response the use of carbon-based ink mixed with gold nanoparticles and commercial screen printed electrodes provided alternative platforms to support the DNA switch electrochemical sensor.
During the PREMOTHER project several scientific and public dissemination activities were carried out. Regarding the former, the researcher presented at two international scientific conferences, authored two peer-reviewed manuscripts (plus other in preparation) and establishing collaboration with clinical and scientific partners. Regarding the latter, the researcher engaged with both university and elementary school students, took part to an online discussion about serological tests and prepared PREMOTHER-dedicated webpage and flyers.
The ability to conveniently and precisely diagnose HIV and syphilis in pregnant women has the potential to save thousands of lives every year. The PREMOTHER project aimed at providing a tool to do just that. Although it seems that the DNA-switch electrochemical sensor is not compatible with the use of graphene-based electrodes, the use of alternative screen printed electrodes looks like a promising way to widely deploy this type of sensor in both low- and high-income countries. In addition the bioinformatic analysis of syphilis antigens and their future clinical validation will allow the development of cheaper and more robust sensing strategies for syphilis.