Colloidal Polyelectrolyte Complexes from Hyaluronic Acid: Preparation and Biomedical Applications

Abstract

nanocomplexes, [8,9] nanocomposites, [10,11] nanoassemblies [12] and coacervates. [13,14] Such colloidal systems, especially when prepared from biopolymers, have been extensively investigated due to their promising properties for numerous applications in biomedical fields. [1] Their merits come from the combination of three aspects: nanomedicine, biomaterials, and green chemistry. With the emergence of nanomedicine, the use of nanocarriers can offer tremendous advantages in drug encapsulation and delivery, namely enhancing the chemical stability of drugs and improving drug solubility and bioavailability. [15] Due to their small size and the possibility of surface modification with biological ligands or molecular imprinting, nanocarriers can easily cross biological barriers, which have limited pore sizes (fenestrations) under 1 micron in most cases, then target and enter the tissues or cells of interest. [16,17] Due to these aspects and the possibility of controlling drug distribution and release through particle engineering, nanocarriers can thus reduce systemic side effects and enhance the therapeutic efficacy of drugs. [15] Nanosystems can also offer unique advantages for biomedical imaging with their ability of sensing, image enhancement, and incorporating concomitantly therapeutic agents for theranostics, that is, simultaneous therapeutic and diagnostic applications. [18][19][20] When constructed from biomaterials, especially naturally occurring polysaccharides or proteins, PECs can become significantly biocompatible and biodegradable with much less immunogenicity and toxicity. [21] Besides such biorelevant aspects, the elaboration of biopolymerbased PECs is also in accordance with green chemistry principles since their preparation process usually requires only gentle mixing of polyelectrolyte solutions at room temperature, which is a simple and rapid procedure without the need for chemical agents, surfactants, organic solvents or high mechanical or thermal energy. [15] Beyond the above-mentioned basic advantages, the potential of colloidal PEC systems is increased by the inherent biological and chemical properties of individual constituent polymers. Hyaluronic acid (HA), also called hyaluronan to generally mention both its acid and salt forms, has been one of the most common polyanions among several biopolymers reported so far for the elaboration of colloidal PECs. The significant attention dedicated to HA in biomedical fields is associated with its unique advantages, stemming from not only its outstanding biocompatibility but also interesting biological activities. [22] Hyaluronic acid (HA) is a naturally occurring polysaccharide which has been extensively exploited in biomedical fields owing to its outstanding biocompatibility. Self-assembly of HA and polycations through electrostatic interactions can generate colloidal polyelectrolyte complexes (PECs), which can offer a wide range of applications while being relatively simple to prepare with rapid and "green" processes. The advantages of colloidal HA-base...

Co-encapsulation of Quercetin and α-Tocopherol Bioactives in Zein Nanoparticles: Synergistic Interactions, Stability, and Controlled Release

“…Previous studies have indicated that electrostatic interactions between zein nanoparticles and other bioactive compounds, such as quercetin and curcumin, can alter the zeta potential. , The observed zeta potential for the Zein/Que/Toc nanoparticles not only aligns with the widely accepted notion of adequate electrostatic stabilization (absolute value of the zeta potential exceeding 30 mV) but also underscores the effectiveness of incorporating α-tocopherol and quercetin into zein nanoparticles in maintaining nanoparticle stability. Additionally, the observed zeta potential of the Zein/Que/Toc nanoparticles aligns with the effectiveness of co-encapsulation in biological environments, validating the maintenance of colloidal stability …”

Lyophilization for Formulation Optimization of Drug-Loaded Thermoresponsive Polyelectrolyte Complex Nanogels from Functionalized Hyaluronic Acid

“…Logically, a higher absolute zeta potential at the beginning would allow a greater electrostatic repulsion to avoid such aggregation and also facilitate disaggregation during the reconstitution, which was also observed by Umerska et al [ 11 ] and Eliyahu et al [ 19 ]. Furthermore, the higher proportion of HA on the NG surface may also contribute to their better stability during freezing since HA can also have cryoprotective effects [ 1 ], e.g., by maintaining intra- and inter-molecular hydrogen bonds on the particle surface during dehydration [ 20 ]. However, after freeze-drying and reconstitution, we still observed an increase of nearly 40% in the particle size of HA/DEAE-D PEC-NGs at n−/n+ = 2.5 ( Table 1 ), which was also the most interesting n−/n+ for CUR encapsulation reported in our earlier studies [ 4 ].…”

“…Nanogels (NGs) from polyelectrolyte complexes (PECs) of hyaluronic acid (HA) have been extensively studied in recent years as biomedical platforms with high potential that have the advantages of nanomedicine, green chemistry, and the inherent properties of HA [ 1 ]. Meanwhile, thermoresponsive nanocarriers from thermosensitive polymers exhibiting a lower critical solution temperature (LCST), i.e., increased hydrophobicity upon temperature increase, have also received great attention over the last two decades for drug delivery applications owing to their interesting behaviors, notably thermo-triggered drug release which can be controlled spatiotemporally [ 2 , 3 ].…”

Microporous Polyelectrolyte Complexes by Hydroplastic Foaming

“…Polyelectrolytes are polymers with repeating units that have the ability to dissociate in ionizing solvents (e.g., water), yielding a highly charged main chain with either positive or negative charges . Mixing of oppositely charged polyelectrolytes in aqueous solutions can lead to rapid precipitation of amorphous solids known as polyelectrolyte complexes (PECs). − The complexation between polyelectrolytes is a process mainly driven by ion pairing of charged repeat units and entropic release of bound counterions. − In the past decades, PECs have emerged as an attractive category of materials due to their water processability, tunable compositions and functions, and some similarities to natural biopolymers. − In particular, porous PEC materials can offer abundant surface area and internal volume for further applications in many cutting-edge areas, including but not limited to separation, catalysis, and biomedical systems. − In this context, several strategies have been proposed to yield porous PEC materials with controllable porosity and morphology. One approach is aqueous phase separation (APS). − In this method, a viscous solution containing oppositely charged polyelectrolytes is prepared at extreme pH conditions or in the presence of excess salt, which can break interchain ion pairs and therefore prevent polyelectrolyte complexation.…”