Somatostatin Decorated Quantum Dots Nanoparticles for Targeting of Somatostatin Receptors

Document Type: Research article

Authors

1 Pharmaceutics department, Faculty of Pharmacy, Al-Azhar University at Assiut

2 Department of Pharmaceutics and Industrial pharmacy, Faculty of Pharmacy, Al-Azhar University, Assuit, Egypt.

3 Department of Pharmaceutics and Industrial pharmacy, Faculty of Pharmacy, El-Minia University, El-Minia, Egypt

Abstract

Due to the unique optical properties like high brightness and narrow emission bands of Quantum dots, it is used as simple fluorescence materials in bio-imaging, immunoassays, microarrays, and other applications. To easy invistigate cell lines that overexpressed somtostatin receptors, somatostatin (SST) was conjugated with Quantum dots carrying PEG amine (Qdots-PEG-NH2). The conjugation of SST to Qdots-PEG-NH2 started with the thiolation of SST using Traut’s reagent. Moreover, the Qdots-PEG-NH2 were subsequently activated by 500-fold molar excess of sulfosuccinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate (sulfo-SMCC) dissolved in phosphate buffer. The Qdots-PEG-NH2-sulfo-SMCC was conjugated to the thiolated-SST to form Qdots-SST. The number of sulfhydryl groups can be controlled by the molar ratio of Traut´s reagent to SST. Thiolation was necessary for the conjugation of SST to Qdots-PEG-NH2. This was achieved by reacting the SST with Traut’s reagent in a 1:1 molar ratio. Ellman’s reagent was used to determine the number of sulfhydryle groups. Furthermore, cellular uptake study on Triple negative breast cancers cells (HCC-1806) showed that the number of Qdots-SST per cell were significantly higher compared to unmodified Qdots-PEG-NH2 when quantified using inductively coupled plasma optical emission spectroscopy (ICP-OES). Moreover, the binding of Qdots-SST to cells can be suppressed by addition of antagonist, indicating that the binding of Qdots-SST to cells due to receptor-specific binding.

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