Synthesis of Alginate Nanoparticles Using Hydrolyzed and Enzyme-Digested Alginate Using the Ionic Gelation and Water-in-Oil Emulsion Method

Abstract

Alginate nanoparticles (AlgNPs) are attracting increasing interest for a range of applications because of their good biocompatibility and their ability to be functionalized. Alginate is an easily accessible biopolymer which is readily gelled by the addition of cations such as calcium, facilitating a cost-effective and efficient production of nanoparticles. In this study, AlgNPs based on acid hydrolyzed and enzyme-digested alginate were synthesized by using ionic gelation and water-in-oil emulsification, with the goal to optimize key parameters to produce small uniform (<200 nm) AlgNPs. By the ionic gelation method, such AlgNPs were obtained when sample concentrations were 0.095 mg/mL for alginate and CaCl2 in the range of 0.03–0.10 mg/mL. Alginate and CaCl2 concentrations > 0.10 mg/mL resulted in sizes > 200 nm with relatively high dispersity. Sonication in lieu of magnetic stirring proved to further reduce size and increase homogeneity of the nanoparticles. In the water-in-oil emulsification method, nanoparticle growth was confined to inverse micelles in an oil phase, resulting in lower dispersity. Both the ionic gelation and water-in-oil emulsification methods were suitable for producing small uniform AlgNPs that can be further functionalized as required for various applications.

Antibacterial and in vitro anticancer activities of the antimicrobial peptide NRC‐07 encapsulated in chitosan nanoparticles

“…Here, the lyophilized AMP NRC‐07 was encapsulated into CS‐NPs by ionotropic gelation. The method was selected given that it does not require the use of heat and organic solvents and hence avoids the denaturation of sensitive macromolecular therapeutics 34,41,49,50 . The latter is underpinned by reports in literature indicating the successful outcome for the delivery by CS‐NPs of peptides and proteins, 33,37–40,47 nucleic acid‐based therapeutics 30 and small molecule therapeutics 31,51–53 …”

“…The method was selected given that it does not require the use of heat and organic solvents and hence avoids the denaturation of sensitive macromolecular therapeutics. 34,41,49,50 The latter is underpinned by reports in literature indicating the successful outcome for the delivery by CS-NPs of peptides and proteins, 33,[37][38][39][40]47 nucleic acid-based therapeutics 30 and small molecule therapeutics. 31,[51][52][53] To confirm the ability of the NPs to deliver its loaded cargo into the cell of interest, the association of the NPs to cancer cells and bacterial cells was initially determined.…”

“…Encapsulation of sensitive bioactive substances, such as proteins and peptides, to increase their stability and activity is well established 25,32 . The technique of ionotropic gelation—using charged polymers—especially CS—in a solution of the bioactive substance that form nanovesicles upon gradual addition of counterions has been used to encapsulate various biomedicals since well over 20 years 33–41 …”

“…25,32 The technique of ionotropic gelation-using charged polymers-especially CS-in a solution of the bioactive substance that form nanovesicles upon gradual addition of counterions has been used to encapsulate various biomedicals since well over 20 years. [33][34][35][36][37][38][39][40][41] Here we show a route to prepare CS-encapsulated NRC-07 and evaluate the antibacterial activity and toxicity against cancer cells of NRC-07-loaded NPs. CS-NRC-07 NPs showed better efficacy against Pseudomonas aeruginosa and breast cancer cells than the free NPs or free peptide, suggesting clinical potential for such drug-loaded NP formulations.…”

Thermo-Responsive Hydrogels Encapsulating Targeted Core–Shell Nanoparticles as Injectable Drug Delivery Systems

“…The empty (without drug) alginate nanoparticles were prepared according to procedures described in the literature with slight modifications [ 52 ]. Briefly, low viscosity sodium alginate (0.5% by weight) was physically cross-linked with calcium chloride at a ratio of 19:1 by volume for 2 h at room temperature to obtain nanoparticles.…”