DNADNA quantification using gold nanoparticles (AuNPs) require the reduction of non-specific binding between AuNPsAuNPs to attain both good dispersability and high hybridizationHybridization efficiency. We employed oligoethylene glycol into the alkanethiolAlkanethiol with a COOH terminus for modification of the AuNP surface, The efficiency of AuNP dimerizationDimerization mediated by hybridizationHybridization between two probe DNADNA molecules and a complementary target DNA molecule was maximized by examining several possible hybridization combinations. And the AuNP concentration is critical to determining the maximum quantification limit. A coupling of AuNPsAuNPs modified with COOH-terminated alkanethiolAlkanethiol by van-der-Waals interaction between alkyl chains was employed, the tunability of the interparticle gap by changing the alkyl chain length, we achieved an interparticle gap as small as 1.0 nm for SERSSurface-Enhanced Raman Spectroscopy (SERS) sensingSensing.