Project Lead(s): Lilia Fernando
Dengue is considered a major global health problem.
In the first nine months of 2013, about 117,658 dengue cases were reported in the Philippines, with 433 recorded deaths. At least 40% of the infected patients were children aged 1–10 years old.
Due to increased prevention efforts, detection of dengue-carrying mosquitos has now become a priority. However, this is usually not possible in local communities – where rapid, sensitive and low-tech detection methods are most needed – because current detection methods are either too expensive, not sensitive enough, labour-intensive or time-consuming.
The objective of this project was to develop simple and inexpensive field-operable biosensors, to screen and monitor the presence of dengue virus in mosquitos and in environmental samples.
The study aimed to exploit the properties of the synthesized dextrin-capped gold nanoparticles to fabricate a nanoparticle-based sensor and provide a rapid, cost-effective, ‘greener’ and portable way of detecting the dengue virus-3 in Aedes aegypti.
Nanoparticle-based sensors are widely used in pathogen detection and have been reported to provide a rapid and sensitive detection of different pathogens such as Human Immunodeficiency Virus Type 1 (HIV-1) p24 antigen, Salmonella DT104, and Escherichia coli O157:H7, among others. Gold nanoparticles (AuNPs), in particular, show promising applications in biomedicine.
The specific objectives of this study were as follows:
· To conjugate the DNAzyme detector probes to the synthesized dextrin-capped gold nanoparticles
· To determine the optimum parameters for the colourimetric detection, using DNAzyme-functionalized gold nanoparticles
· To perform the colourimetric detection using both synthetic DENV-3 target oligonucleotide and extracted RNA from Aedes aegypti
· To assess the selectivity of the nanoparticle-based sensor
· To determine the effect of varying target concentrations on the absorbance of the aggregated gold nanoparticles.
Functionalized magnetic nanoparticles were used to capture the dengue virus samples, which were then tagged with gold nanoparticle-conjugated antibodies. Differential pulse voltammetry was then used to detect the gold nanoparticles on the surface of a screen-printed carbon electrode.
The biosensor showed potential to determine the level of infection in patients to 5 x 102 PFU/mL using extracted RNA from A. aegypti.
Compared to conventional methods, detection using the nanobiosensor is fast (taking less than one hour to perform) and is inexpensive. The sensitivity, speed, and low cost of this biosensor make it a promising means of diagnosing dengue fever in affected countries and reducing the spread of the disease.
Knowledge of the project was published and presented at conferences.
The project team plans to apply for Transition To Scale (TTS) funding and to partner with private investors to conduct validation studies to further test the prototype.