Intracellular fluorescent light-up bioprobes with different morphology for image-guided photothermal cancer therapy

Multifunctional nanoprobe was drawing increased attention in tumor diagnosis and therapy. The simple and effective establishment of the theranostic nanoplatforms was still under urgent need. Meanwhile, the targeting ability and morphology of nanoprobe were essential for the effective endocytosis, which could further affect the diagnosis. In this work, two morphologies of nanoprobes were fabricated using gold nanorods (AuNRs) and gold nanospheres (AuNSs). Thiolated-hyaluronic acid labeled with nile blue (HS-HA-NB), a near-infrared (NIR) fluorescence dye, was coated on the surface of the gold nanoparticles to form stable nanoprobes (AuNR@HS-HA-NB, AuNS@HS-HA-NB). The fluorescence of NB molecules quenched outside cells due to the fluorescence resonance energy transfer (FRET), and recovered after the HA degradation inside the cells. HA also could enhance cellular uptake in CD44 receptor highly expressed human breast carcinoma cells (MCF-7). In this way, bioprobes realized the MCF-7 cell images through intracellular fluorescent light-up. Comparing with the sphere bioprobe, the rod-shaped bioprobe dramatically promoted endocytosis to achieve a better diagnosis effect in a short time. After NIR light irradiation, severe MCF-7 apoptosis was observed with AuNR@HS-HA-NB existed. Our studies suggested that the AuNR@HS-HA-NB nanoparticles were the excellent candidates of versatile bioprobes to realize rapid, precise image and photothermal therapy to MCF-7 cells.