In recent years, in addition to the classic drugs, addiction to a series of new drug classes known as club drugs has increased significantly. Fast and lowcost bioassay for the detection of amphetamine-based drugs can be an effective strategy towards reducing their abuse. In this study, we designed a sensitive bioassay strategy using gold nanoparticles (GNPs) and the aptamers that possess high affinity toward methamphetamine (MA). It is suggested that the aptamer adopts different tertiary structures in the presence and/or absence of its specific target and GNPs can effectively differentiate between these two states by their characteristic surface plasmon resonance-based colour change. Visual detection of MA and 3,4-methylenedioxy-N-methylamphetamine (MDMA) in the low micromolar range is possible within minutes with the use of this method.

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Different expression systems such as bacteria and mammalian cells have been used to produce pharmaceutical proteins. In recent years, the use of plants as bioreactors offers efficient and economical systems in recombinant protein production. Furthermore, because of the large number of plastid copies in plants, chloroplast engineering functions as an effective method to increase recombinant protein expression. Because the commercially available insulin for treatment does not contain C-peptide, which is of great importance for type 1 diabetic patients, the current study introduces the human proinsulin gene fused with protein A into the tobacco chloroplast genome using the biolistic method. To achieve homoplasmy, three rounds of selection and regeneration of transforming cells were performed on the medium that contained spectinomycin antibiotic and hormones. The PCR analysis indicated the presence of the proinsulin gene in transplastomic plants. The reverse-transcription PCR analysis confirmed the expression of the proinsulin-protein A fusion at the transcription level. Immunoblot assays of leaf-derived protein extracts confirmed that the target gene expression is up to 0.2% of the total soluble protein. Our study showed that protein A fusion is not as efficient as other reported fusions. The transplastomic plants were also confirmed for homoplasmy using Southern blot analysis.