Cellular uptake and fate of cationic polymer-coated nanodiamonds delivering siRNA: a mechanistic study

• Published in: Nanoscale Vol. 16; no. 5; pp. 249 - 253
• Main Authors: Majer, Jan, Kindermann, Marek, Pinkas, Dominik, Chvatil, David, Cigler, Petr, Libusova, Lenka
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 01.02.2024
• Subjects: Biocompatibility; Cationic polymerization; Cations; Cell Line, Tumor; Copolymers; Diamonds; Ethylamines; Humans; Methacrylamide; Methacrylates; Nanodiamonds; Nanostructure; Polymer coatings; Polymers; RNA, Small Interfering - metabolism; Stability; Toxicity
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d3nr05738k

Gene silencing using small interfering RNAs (siRNAs) is a selective and promising approach for treatment of numerous diseases. However, broad applications of siRNAs are compromised by their low stability in a biological environment and limited ability to penetrate cells. Nanodiamonds (NDs) coated with cationic polymers can enable cellular delivery of siRNAs. Recently, we developed a new type of ND coating based on a random copolymer consisting of (2-dimethylaminoethyl) methacrylate (DMAEMA) and N -(2-hydroxypropyl) methacrylamide (HPMA) monomers. These hybrid NDpolymer particles (Cop + -FND) provide near-infrared fluorescence, form stable complexes with siRNA in serum, show low toxicity, and effectively deliver siRNA into cells in vitro and in vivo . Here, we present data on the mechanism of cellular uptake and cell trafficking of Cop + -FND:siRNA complexes and their ability to selectively suppress mRNA levels, as well as their cytotoxicity, viability and colloidal stability. We identified clathrin-mediated endocytosis as the predominant entry mechanism for Cop + -FND:siRNA into U-2 OS human bone osteosarcoma cells, with a substantial fraction of Cop + -FND:siRNA following the lysosome pathway. Cop + -FND:siRNA potently inhibited the target GAPDH gene with negligible toxicity and sufficient colloidal stability. Based on our results, we suggest that Cop + -FND:siRNA can serve as a suitable in vivo delivery system for siRNA. Nanodiamonds coated with a random cationic copolymer based on (2-dimethylaminoethyl) methacrylate (DMAEMA) and N -(2-hydroxypropyl) methacrylamide (HPMA) enable highly effective cellular delivery of siRNAs. Clathrin-mediated endocytosis is the predominant entry mechanism.