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Use of plasmonic biosensor to monitor protein post translation
( Nguyen Hung Anh ),심상준 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1
Postranslation of proteins plays an important role in their correct folding and functions. Using proinsulin as a model, we here report a nanoplasmonic biosensor to (i) detect serum insulin concentration and (ii) monitor a conformational conversion from proinsulin to mature insulin. The basis of the sensor is based on plasmonics-based refractometric sensor due to binding, conformational changes of insulin on the sensor surface. The limit of detection for insulin in the serum increases from 100 fM (primary response) to 1 fM (100 times) after enhancement by the immunogold colloids. The probes of anti-C peptide-antibody-nanoparticle conjugates are used to detect proinsulin in the mixture with mature insulin at 20 fM. Moreover, real time monitoring for the conformational conversion from proinsulin to mature insulin reveals misfolded insulin, C-peptide mutant sites and kinetics of the conversion.
김우현,( Nguyenhunganh ),심상준 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Circulating tumor DNA (ctDNA) are promising biomarker for noninvasive cancer assay in tumor-specific mutation and methylation. However, previous methods for ctDNA detection have limitation in genetic mutations. Here we present a strategy for ultrasensitive detection of tumor-specific mutations and methylation of ctDNA based on localized surface plasmon resonance (LSPR) and the coupling plasmon mode of gold nanoparticles (AuNPs). Peptide nucleic acid (PNA) is used as a probe to capture and enrich ctDNA. The exposure of PNA-probed AuNPs to target ctDNA generates the primary response of LSPR-peak shift. Immunogold colloids are exploited as methylation detectors and plasmon coupling enhancers for secondary response. LSPR-peak shift is increased approximately 107% upon immunogold colloids binding to two methylcytosines, compared to the primary response. These results demonstrate that the sensor can simultaneously detect the hot-spot mutation and epigenetic changes on the ctDNA.
전명진,( Nguyenhunganh ),심상준 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Cytosine methylation in DNA refers to genetic changes without mutation of actual genetic nucleotide sequence. DNA methylation in certain genes is deeply involved in several fatal diseases, but current methods for detecting methylation entails high cost and large sample size. Here, we developed a surface-enhanced Raman spectroscopy (SERS)-based platform for detecting global DNA methylation state. The methylation sites were detected with anti-mCpG immunogold colloids, and the signal was enhanced with plasmon coupling effect. The DNA samples were absorbed onto positively-charged surface of silver nanowire (AgNW) and immunogold colloids were attached on methylated sites. The detection limits for global methylated DNA on the silver nanowires were 18 fg/mL.