Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), which acts as the next generation of advanced spectroscopy, expands the versatility of surface-enhanced Raman spectroscopy (SERS). Here we present a facile one-step method to prepare functionalized core-shell nanoparticles for selective detection of trinitrotoluene (TNT) through the formation of Meisenheimer complexes. A well-designed type of tunable poly(2-aminothiophenol) (PAT) shells on gold nanoparticles was prepared for the first time and the shell thickness of 2 nm could be controlled by only adjusting the molar ratio of sodium dodecylsulfate (SDS) to 2-aminothiophenol. The polymer shells shows prominent advantages, including uniformity, better chemical stability, being free of pin-holes and amino-functionalized.