Engineered Doxorubicin Delivery System Using Proteinoid-Poly (L-Lactic Acid) Polymeric Nanoparticles of Narrow Size Distribution and High Molecular Weight for Cancer Treatment

Abstract

Doxorubicin (Dox), a widely used anti-cancer drug, was encapsulated within new special-tailored proteinoid nanoparticles (NPs), with the intention to overcome side effects while keeping the drug potency. The synthesis and characterization of four newly-made proteinoids of very high molecular weights (122-149 kDa) and low polydispersity (1.01-1.03) is presented. The proteinoids were synthesized from L-lysine, L-arginine, L-histidine, L-phenylalanine and poly-L-lactic acid (PLLA) segments, and are named P(KRHF-PLLA). Using this selection of amino acids provides basic positive-charged novel tailored proteinoids, with a rigid and biodegradable backbone, achieved by the incorporation of PLLA. The proteinoids self-assemble to yield NPs of a narrow-size distribution. This self-assembly procedure was utilized to encapsulate Dox within the NP core. The optimal Dox-encapsulated NPs were chosen by a study of their size, size distribution and Dox content. The chosen NPs, 15% Dox-loaded P(KRHF-PLLA) NPs were checked for their stability in different conditions. In order to improve tumor uptake and time of circulation in the blood, the chosen NPs were further PEGylated and the effects of PEGylation of the NPs, as well as the effect of the environment, on the release rate of Dox from the NPs were investigated. Additionally, the cytotoxicity of the PEGylated and non-PEGylated Dox-containing NPs was studied by XTT assay and their generation of immune-response was investigated by cytokines induction assay. Overall, the Dox-loaded NPs were found stable, non-immunogenic and showed good cell toxicity, making them good candidates to be used against cancer, while PEGylation improved all parameters.

Synthesis and Characterization of Poly(RGD) Proteinoid Polymers and NIR Fluorescent Nanoparticles of Optimal d,l-Configuration for Drug-Delivery Applications—In Vitro Study

“…Table 1 exhibits the molecular weights and polydispersity indices (PDIs) of the R D GD, R D GD D , RGD, and RGD D proteinoid polymers. The relative high molecular weights (67,660−69,066 Da) and the very narrow molecular weight monodispersity are not expected but fit to our previous publications 18,24,25 because common stepgrowth polymerization processes result in low-molecularweight polymers with broad molecular weight polydispersity. 26 The R D GD, R D GD D , RGD, and RGD D proteinoids were characterized by Fourier transform infrared (FTIR) spectroscopy and ultraviolet−visible (UV−vis) spectroscopy.…”

“…Proteinoids are polymers which consist of natural or synthetic amino acids and are synthesized by bulk thermal step-growth polymerization mechanism. This special procedure was discovered by Fox and Harada. − The formation of proteinoids is carried out in the absence of a catalyst or solvent by heating in an inert atmosphere of certain amino acids, such as aspartic acid, glutamic acid, or lysine, to their melting point, leading to the initiation of the polymerization of the amino acids. − The suggested explanation for the polymerization process is that aspartic acid, for example, serves as a solvent for the other amino acid monomers as it is condensed through cyclization upon heating into 2,2′-(3,6-dioxopiperazine-2,5-diyl)­diacetic acid, which initiates the polymerization with the rest of the amino acids, thus forming the proteinoid polymer, as shown in Figure …”

“…The proteinoids are considered to be nonimmunogenic (as illustrated in our previous work by cytokines induction assay), biodegradable, and nontoxic. , Hence, they serve as a delivery carrier in the human body. Hollow proteinoid NPs can be produced by a self-assembly process of the proteinoids in an aqueous solution.…”

“…14−17 The suggested explanation for the polymerization process is that aspartic acid, for example, serves as a solvent for the other amino acid monomers as it is condensed through cyclization upon heating into 2,2′-(3,6-dioxopiperazine-2,5diyl)diacetic acid, which initiates the polymerization with the rest of the amino acids, thus forming the proteinoid polymer, as shown in Figure 1. 18 The proteinoids are considered to be nonimmunogenic (as illustrated in our previous work by cytokines induction assay), biodegradable, and nontoxic. 18,19 Hence, they serve as a delivery carrier in the human body.…”