Gold nanoparticle-oligonucleotide conjugate to detect the sequence of lung cancer biomarker

Aimml: The aim of this project was to synthesize and characterize gold nanoparticles (GNPs) to trace the sequence of the hnRNPB1as a lung cancer biomarker.

In the synthesis of GNPs with characteristics appropriate for conjugation, the size, morphology, and shape of the synthesized GNPs were determined by using spectrophotometry and transmission electron microscopy (TEM), followed by designing a probe for hnRNPB1biomarker with characteristics suitable for conjugation. Next, the GNPs were functionalized with a single-stranded DNA probe that was specific for the biomarker, for the characterization and confirmation of the conjugation process. Finally, for determination of minimum level of detection in solution including DNA target and probe aggregation, the changes in the absorption spectra of the samples in the range of 250-750 nm were determined using the NanoDrop ND 1000 spectrophotometer.

The surface of GNPs can be modified by utilizing ligands to selectively attach biomarkers. Thiol-bonding of DNA and chemical functionalization of GNPs are the most common approaches. Colloidal gold was synthesized with the citrate reduction method, as described by Turkevich et al. in 1951. In this study, the probe for hnRNPB1 was designed with a thiol crosslinker. Every set of conjugated GNPs was complementary to one end of the hnRNPB1 biomarker, and the probes were aligned in a tail to tail fashion onto the target.

Uniform GNPs were synthesized by the citrate reduction technique, and the outcomes of trials with variation in factors (shape and size of the nanoparticles, gold concentration, and conjugation between GNP and probes) were investigated. The gold nanoprobe-based technique is better than the PCR-based techniques, because there are no requirements of enzymatic amplification and gel electrophoresis, and the evaluation can be done using small amounts of sample.