Biotin-decorated silica coated PbS nanocrystals emitting in the second biological near infrared window for bioimagingElectronic supplementary information (ESI) available: Size statistical analysis of silanized PbS NPs, TLC plate showing the ninhydrin test results and a table summarizing the DH and ζ-potential values for the investigated samples. See DOI: 10.1039/c4nr01025f

• Main Authors: Corricelli, M, Depalo, N, Di Carlo, E, Fanizza, E, Laquintana, V, Denora, N, Agostiano, A, Striccoli, M, Curri, M. L
• Format: Journal Article
• Language: English
• Published: 26.06.2014
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c4nr01025f

Nanoparticles (NPs) emitting in the second biological near infrared (NIR) window of the electromagnetic spectrum have been successfully synthesized by growing a silica shell on the hydrophobic surface of OLEA/TOP PbS nanocrystals (NCs), by means of a reverse microemulsion approach, and subsequently decorated with biotin molecules. The fabrication of very uniform and monodisperse NPs, formed of SiO 2 shell coated single core PbS NCs, has been demonstrated by means of a set of complementary optical and structural techniques (Vis-NIR absorption and photoluminescence spectroscopy, transmission electron microscopy) that have highlighted how experimental parameters, such as PbS NC and silica precursor concentration, are crucial to direct the morphology and optical properties of silica coated PbS NPs. Subsequently, the silica surface of the core-shell NPs has been grafted with amino groups, in order to achieve covalent binding of biotin to NIR emitting silica coated NPs. Finally the successful reaction with a green-fluorescent labelled streptavidin has verified the molecular recognition response of the biotin molecules decorating the PbS@SiO 2 NP surface. Dynamic light scattering (DLS) and ζ -potential techniques have been used to monitor the hydrodynamic diameter and colloidal stability of both PbS@SiO 2 and biotin decorated NPs, showing their high colloidal stability in physiological media, as needed for biomedical applications. Remarkably the obtained biotinylated PbS@SiO 2 NPs have been found to retain emission properties in the 'second optical window' of the NIR region of the electromagnetic spectrum, thus representing attractive receptor-targeted NIR fluorescent probes for in vivo tumour imaging. Biotin-decorated silica coated PbS nanocrystals emitting in the 'second near infrared biological window' of the electromagnetic spectrum as robust and attractive receptor-targeted NIR fluorescent probes for in vivo tumour imaging.