Layer-by-layer polyelectrolyte coating of alginate microgels for sustained release of sodium benzoate and zosteric acid

Abstract

The potential of sustaining release of very small (Mw < 250 g/mol) hydrophilic drugs up to several days from layer-by-layer (LbL) polyelectrolyte coated alginate microgels (Alg-Ms) was investigated. One purpose is to minimize post-surgical adhesions, which develop in 12 h to 3 days after surgery. The LbL polyelectrolyte layer would serve as a diffusion barrier for their release. The LbL polyelectrolyte bilayers were prepared using poly(allylamine) (PAH) and poly(styrene sulfonate) (PSS). Sodium benzoate (NaB, Mw = 144 g/mol) and zosteric acid (ZA, Mw = 244 g/mol), two anti-inflammatory and anti-microbial compounds, were used as model drugs. A higher number of PAH/PSS bilayer lead to a greater sustained release of both drugs, and with 4 bilayers, the release of NaB and ZA was prolonged from 24 h to 72 h and 120 h, respectively. Fitting the data to the Ritger-Peppas’ equation showed that as the bilayer number increased, the release constant and/or exponent decreased, indicating the LbL PAH/PSS bilayer effectively reduced the permeability of these two very small hydrophilic drugs. The ability to prolong the release of such small hydrophilic molecules, which has rarely been investigated previously, would find broad applications in fields such as anti-adhesion treatment and antifouling coatings.

Alginate-Based Edible Films and Coatings for Food Packaging Applications

“…Wang and Zhang Newby [ 240 ] showed that LbL polyelectrolyte alginate microgels significantly retard the release of small hydrophilic molecules (MW < 250 g/mol).…”

Development of a Polysaccharide-Based Hydrogel Drug Delivery System (DDS): An Update

“…The particulates of hydrogels on the size scale ranging from 10 nm to 5 μm, known as microgels or nanogels, are of growing interest for the delivery of specific therapeutic drugs to specific sites in the body [41]. In general, microgels less than 5 μm in diameter are suitable for oral and pulmonary delivery, while nanogels with a 10-100 nm diameter can be used for systemic drug administration.…”

Methacrylated Gellan Gum/Poly-l-lysine Polyelectrolyte Complex Beads for Cell-Based Therapies

“…The most used cell encapsulation strategy still relies on a layer-by-layer (LbL) deposition of the materials to form stable capsules, such as the alginate-poly- l -lysine-alginate (APA) system . However, such LbL strategy may hinder the diffusion of essential nutrients, since flow properties can decrease with the increasing number of layers . Thus, although other authors reported the successful application of alginate microcapsules in T1DM treatment, using different diabetic models like rodent, porcine, canine, and non-human primates, reports of human clinical trials still show some complications, including finite normoglycemia, lack of functionality of encapsulated cells, and exacerbated fibrotic overgrowth …”

“…5 However, such LbL strategy may hinder the diffusion of essential nutrients, since flow properties can decrease with the increasing number of layers. 6 Thus, although other authors reported the successful application of alginate microcapsules in T1DM treatment, using different diabetic models like rodent, 7 porcine, 8 canine, 9 and non-human primates, 10 reports of human clinical trials still show some complications, including finite normoglycemia, lack of functionality of encapsulated cells, and exacerbated fibrotic overgrowth. 11 As an alternative, polyelectrolyte complex (PEC) hydrogels result from a one-step reaction between two polyelectrolyte polymers of opposite charges.…”