A wide range of cadmium sulfide (CdS) 3D polycrystalline walnut-like nanocrystals were prepared by solvothermal method with polyvinyl pyrrol idone (PVP) as stabilizer. The morphology, structure, and phase composition of the as-prepared CdS nanoparticles were examined by using various techniques (X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED)). The optical properties of CdS were characterized by photoluminescence (PL) spectra. The paper showed that when the proper dosage of PVP (0.12g50mL(-1))and the temperatureof reaction (120 degrees C) were taken, continuous polycrystallinenanoparticles with regular morphology were obtained. The mechanism for the PVP-assisted synthesis of US 3D nanostructures and the growth process of CdS nanoparticles via Ostwald Ripening process under different temperatures with different dosages of PVP were also investigated. A sensitive electrochemical detection device of DNA hybridization using a paste glass carbon electrode (GCE) assembled by the PVP-capped US nanoparticles and immobilizing DNA probe was developed as a novel application of nano-semiconductors such as US to achieve a notable amplification in sensor response. (c) 2008 Elsevier B.V. All rights reserved.