Development of DNAzyme-gold nanoparticle-based biosensor for the examination of lead ion (Pb2+) contamination in human blood and urine

Lead ion contamination in environment becomes one of the big concerns in Thailand in the present as this metal ion is commonly used in a high varieties of industries. People with lead poisoning tend to have a wide range of symptoms. Some of these include abdominal pain, loss of appetite, memory loss, depressed, anemia, kidney and brain damage, and death. Early diagnosis of lead ion contaminant in human may reduce a risk of lead poisoning. However, clinical diagnostic of this disease is quite complex as the pathology of the disease can occur in many organs and the symptoms are also similar to the pathology of other diseases. Gold standard method for lead ion content also requires highly equipped analytical devices, such as, furnace atomic absorption/emission spectrometry, inductively coupled plasma mass spectrometry, X-ray fluorescence spectrometry, and reversed-phase high-performance liquid chromatography, thereby, becoming a limitation for onsite detection of lead ion contaminant particularly for people living in rural areas. From this problem, this project aims to develop a feasible and onsite detectable lead ion detection kit with high sensitivity and low cost. DNAzyme-gold nanoparticles complex on paper-based biosensor is the target of development as DNAzyme itself has a great selectivity to detect a specific type to metal ion. Gold nanoparticles also enable the naked eye visualizability of the signal readout where the intensity of the signal can reflect the target content in the sample. In addition, microfluidic paper-based analytical device (uPAD) allows this developed sensor to be low cost, user-friendly, and onsite detectable allowing high reachability even by people who are not an expert in the contaminant analysis. From these, our developed biosensor has a potential to be an alternative method for onsite lead ion detection with on par, if not superior, effectiveness as compared to other gold standard methodologies in the present.