Deswelling Process Research Articles

Numerical modeling of heterogeneous stimuli-responsive hydrogels

In this paper, we introduce a computational technique for modeling heterogeneous thermoresponsive hydrogels. The model resolves local fluid-solid interactions in hydrogel pores during the deswelling process. The model is a Lagrangian particle-based technique, which benefits from computational grids that represent polymer beads inside hydrogel scaffolds. The results show that the mechanical properties of hydrogels during deswelling, e.g., shrinkage ratio and elastic modulus, have a direct effect on the development of the front of expelled fluid. It is also observed that in certain parameter regimes the hydrogel may generate inertial fluid jets at the early stages of deswelling. Finally, simple heterogeneous designs are developed using Menger sponge-inspired shapes to investigate the effect of design heterogeneity on promoting directional release. Published by the American Physical Society 2024

Percolation-induced gel-gel phase separation in a dilute polymer network.

Cosmic large-scale structures, animal flocks and living tissues can be considered non-equilibrium organized systems created by dissipative processes. Replicating such properties in artificial systems is still difficult. Herein we report a dissipative network formation process in a dilute polymer-water mixture that leads to percolation-induced gel-gel phase separation. The dilute system, which forms a monophase structure at the percolation threshold, spontaneously separates into two co-continuous gel phases with a submillimetre scale (a dilute-percolated gel) during the deswelling process after the completion of the gelation reaction. The dilute-percolated gel, which contains 99% water, exhibits unexpected hydrophobicity and induces the development of adipose-like tissues in subcutaneous tissues. These findings support the development of dissipative structures with advanced functionalities for distinct applications, ranging from physical chemistry to tissue engineering.

Nearly Reversible Expansion and Shrinkage of Casein Microparticles Triggered by Extreme pH Changes.

Solvent flows in the fL/s range across the total surface of a casein microparticle cause its expansion and shrinkage. Microparticles prepared from the milk protein casein have a porous and flexible inner structure with water-filled channels and cavities. Solvent uptake occurs in two phases and results in disintegration if de-swelling is not triggered by acidification. So far, nothing is known about the reversibility of the swelling/de-swelling steps. We performed pH jump experiments between pH 11 and pH 1 on a single micro-particle and analyzed the swelling-induced size changes with system dynamics modeling. Both the swelling steps and the subsequent de-swelling process proceed reversibly and at an unchanged rate over a sequence of at least three pH exchange cycles. We observed that the duration of the first swelling step increased during the sequence, while the second step became shorter. Both of the time intervals are negatively correlated, while a statistical evaluation of only one swelling cycle for an ensemble of microparticles with different stabilities did not reveal any significant correlation between the two parameters. Our results indicate that the pH-induced swelling/shrinkage of casein microparticles is, to a large extent, reversible and only slightly influenced by the acid-induced decomposition of colloidal calcium phosphate.

3-Aminophenylboronic Acid Conjugation on Responsive Polymer and Gold Nanoparticles for Qualitative Bacterial Detection.

Because of their sensitive and selective responses to a wide variety of analytes, colorimetric sensors have gained widespread acceptance in recent years. Gold nanoparticles (AuNPs) are widely employed in visual sensor strategies due to their high stability and ease of use. Combining AuNPs with a responsive polymer can result in distinct surface plasmon resonance (SPR) changes that can be utilized as colorimetric biosensors. The purpose of this research is to develop a colorimetric-based sensor through the utilization of the optical properties of gold nanoparticles (AuNPs) crosslinked with pH-responsive polymers poly (acrylic acid) (PAA) conjugated to 3-aminophenyl boronic acid (APBA). The polymer (PAA) was synthesized via RAFT polymerization. The inversed Turkevic method was used to produce AuNPs, which were subsequently used in a self-assembly process using poly (acrylic acid)-aminophenyl boronic acid (PAA-APBA) to create the self-assembled AuNPs-APBA-PAA. The particle size, zeta potential, and reversibility of the polymer-modified gold nanoparticles were determined using a transmission electron microscope (TEM), a particle size analyzer (PSA), and an Ultraviolet-Visible spectrophotometer (UV-Vis spectrophotometer). Visual, UV-Vis spectrophotometer and TEM observations confirmed the system's ability to identify bacteria. Statistical analysis was performed using a one-way analysis of variance using Excel software. Using UV-Vis spectrophotometry, the particle size of AuNPs was determined to be 25.7 nm, and the maximum absorbance occurred at 530 nm. AuNPs PAA APBA colloid exhibited an absorbance maximum of 532 nm, a zeta potential of -41.53, and a pH transition point between 4 and 5. At E. coli concentrations of 4.5 x 107 CFU/mL, the color of the system sensors changed from red to blue after 15 hours of incubation, whereas at S. aureus concentrations of 1.2 x 109 CFU/mL, the color changed to purple immediately after mixing. The TEM confirmed that the detection mechanism is based on the boronate-polyol bonding of saccharides on the outer membranes of Escherichia coli and Staphylococcus aureus. The use of APBA in conjunction with pH-responsive PAA polymers containing AuNPs to detect E. coli and S. aureus bacteria induces a maximum wavelength transition, followed by a color change from red to blue. By the process of de-swelling of the responsive polymer, which induces the aggregation of the AuNPs, the established sensor system is able to alter the color. The conjugated polymer and gold nanoparticle-based sensor system demonstrated a promising method for bacterial detection.

Effect of Solvents on the Color Recovery Responses of Swollen Structural-Color Epoxy Films Based on Inverse Opal Photonic Crystals.

Photonic crystal (PC) films have been widely applied in color displays and the anticounterfeiting field due to their facile fabrication process and easily tunable properties. However, the method for improving the reusability of the color-changed swollen PC films is still a challenge. In this paper, we report the color recovery behavior of epoxy resin inverse opal photonic crystal (EP-IOPC) films, which show different responses after being infiltrated with ethanol, acetone, and dimethyl sulfoxide (DMSO) based on the swelling and deswelling process. DMSO achieved the best effect on the color recovery of the swollen EP-IOPC films compared to ethanol and acetone, and the reflection spectrum blue-shifted in a small range and finally stabilized at a 60 nm deviation from the original spectrum after 10 times recovery. This strategy of color recovery not only solved the problem that the swollen EP-IOPC film's color changes to a certain extent but also showed promising potential in the color display and anticounterfeiting field.

Role of Charge Content in the Two-Step Deswelling of Poly(N-isopropylacrylamide)-Based Microgels

Poly(N-isopropylacrylamide)-based microgels are soft colloids undergoing a Volume Phase Transition (VPT) close to ambient temperature. Although widely employed for fundamental research and application purposes, the modifications of the microgel internal structure occurring at the VPT are not yet completely understood, especially concerning the role of electrostatics. Here we study in detail, both experimentally and numerically, the effect of the addition of acrylic acid (AAc) co-monomer on the microgel deswelling process. By combining viscosimetry, light scattering and electrophoresis, we show that the progressive addition of AAc increases the microgel mass and suppresses the occurrence of the VPT, progressively shifting the microgel collapse to higher temperatures. Most importantly, it also highly enhances the two-step deswelling of these submicron-sized networks, so that the inner core collapses at temperatures always lower than those marking the transition of the outer corona. These results indicate that a net increase of the charge density mismatch between the bulk and the surface of the microgels takes place. Numerical simulations fully confirm this scenario and clarify the impact of the charge distribution on the two-step deswelling, with mobile counterions efficiently screening the charges within the inner core, while leaving more monomers ionized on the surface. Our work unambiguously shows how electrostatic interactions influence the behavior of thermosensitive microgels in aqueous environment close to the VPT.

Chemical Fuel Mediated Self-Regulatory Polymer Brushes for Autonomous Fluorescence Modulator and Wettability Switcher.

Synthetic systems of nonequilibrium self-assembly have made considerable progress; however, the achievement of innovative materials with self-regulated functions analogous to living systems remains a grand challenge. Herein, a versatile nonequilibrium system of polymer brushes with spatiotemporally programmable properties and functions driven by chemical fuels is reported. By combining a responsive polymer with an autonomous pH regulator, the polymer brushes self-regulate their swelling and deswelling process with tunable lifetimes. By using patterned copolymer brushes with pH-responsive fluorescence moiety, an autonomous fluorescence modulator is created that self-regulates its fluorescence in spatiotemporally programmable fashion driven by a chemical or an enzymatic reaction. Furthermore, a self-regulated wettability switcher of polymer brushes both in air and in an aqueous solution is implemented. The methodology and results in the work provide a useful avenue into the exploration of nonequilibrium synthetic materials with programmable functions and would accelerate the transformative developments of nonequilibrium materials and systems in practical applications.

Fast and opposite temperature responsivity in release behavior of cocontinuous hydrogel composites

For practical implementation, numerous attempts have been made to improve the mechanical durability and response rate of temperature-responsive hydrogels. In this study, the introduction of a cocontinuous structure with polydimethylsiloxane (PDMS), which successfully improved both the properties, was found to reverse the temperature dependence of release behavior. The cocontinuous composites of poly(N-isopropylacrylamide) (PNIPAm) and PDMS were prepared via directional melt crystallization and subsequent infiltration of PDMS. The compressive moduli of composites were more than 30 times higher than those of PNIPAm. Further, the existence of soft hydrophobic PDMS walls against the PNIPAm phases accelerated the deswelling process, and thus, it was more than 2,000 times faster than that of PNIPAm. The deswelling rate increased as the size of PDMS phases increased. The release rate accelerated above the lower critical solution temperature (LCST) and slowed below the LCST, reversibly, thereby opposing the behavior of PNIPAm. Therefore, the fast volume shrinkage of PNIPAm phases confined between PDMS phases is responsible for the unique release behavior of the composites, and not the molecular diffusion processes through hydrogel mesh structures. Collectively, these findings highlight a versatile tool for engineering the release behavior of smart drug carriers based on temperature-responsive hydrogels.

Salt partitioning in ionized, thermo-responsive hydrogels: perspective to water desalination.

Charged hydrogels are capable of swelling in aqueous salt solutions, whereby part of the salt ions is repelled due to the presence of fixed charged groups inside the hydrogel. This effect creates a concentration gradient between the absorbed solution and the surrounding fluid known as salt partitioning, offering a potential for these materials to be employed to desalinate saltwater. If the charged hydrogels are thermo-sensitive as well, then the purer, absorbed solution can be recovered by shrinking the hydrogels upon temperature change. To tailor that potential in water-purification and desalination applications, the main parameters influencing the salt partitioning, the deswelling of the hydrogels, and the recovery of water must be understood. In this paper, we analyze these factors based on equations derived from the Donnan theory. In addition, hydrogels composed of N-isopropyl acrylamide and acrylic acid are synthesized, and their salt rejection efficiency in a model desalination experiment is studied. A comparison of the experimental and the theoretical results demonstrates that the charge density of the hydrogels at their equilibrium swelling and the degree of water recovery are two parameters controlling the salt rejection efficiency. These parameters are individually controlled by the content of the ionic groups and the degree of cross-linking of the gel polymer network. In addition, the prediction of the theory and the experimental results demonstrate that the salt rejection efficiency can be significantly improved if a second water recovery step is performed by a secondary increase in the temperature in the deswelling process.

Symmetry-breaking in double gyroid block copolymer films by non-affine distortion

Soft-matter bicontinuous networks find a double gyroid structure from block copolymer (BCP) self-assembly. A gyroid structure composed of dissimilar blocks has proven its potential as a soft crystal capable of tuning structural periodicity and symmetry, of which the lattice dimension is variable with molecular weight of the polymer. Using an asymmetric polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA), here we show that the self-assembled gyroid films formed via a solvent vapor annealing (SVA) process undergo unique structural distortion due to directional deformation immediately upon deswelling. During the SVA process with PS-b-PMMA films, transient cylinders developed from the as-cast morphology transform into a cubic gyroid structure in a swollen state. Rapid and spontaneous deswelling processes ̶ the manners in which the films contract along the z-direction while retaining an enlarged lateral dimension of the cubic form ̶ lead to triclinic gyroid structures with z-directional contraction ratios (Cz) of 2.5 and 2.0, respectively. Our X-ray analysis reveals that the deswelling process of the swollen gyroid films produces a notable symmetry-breaking in non-affine gyroid structure that elicits several forbidden reflections such as {110} and {200} reflections. For further characterization of the symmetry-breaking, we delineate the structural features of noncubic gyroid films by computing electron-density difference maps assisted with X-ray measurements. Level-set approach is accordingly developed to quantitate the structural characteristics of the maps in terms of inversion symmetry-breaking, suggesting its possible application to optical Weyl photonic crystals.

Thickness and Curvature Changes of Human Corneal Grafts in Dextran-Containing Organ Culture Medium Before Keratoplasty.

To determine the changes of corneal thickness and curvature of human corneal grafts in organ culture medium II, containing dextran T500 6%, before keratoplasty. We examined the tomography of 24 corneas from our eye bank transferred from medium I into medium II. Images were repeated hourly during 24 hours using an anterior segment optical coherence tomography. The central corneal thickness (CCT) was measured with the manual measurement tool of the anterior segment optical coherence tomography. The radii of curvature (anterior flat and steep and posterior flat and steep) were measured with a MATLAB self-programmed software for "sterile donor tomography." The mean CCT (±SD) at baseline (T0) was 727 ± 156 μm. It reached 581 ± 103, 506 ± 84, 472 ± 79, and 456±7 μm after 6, 12, 18, and 24 hours, respectively. After 12 hours, 83% of the final deswelling was achieved. The radii of curvature (±SD) at baseline (T0) were (posterior flat, posterior steep, anterior flat, and anterior steep) 6.6 ± 0.5, 6.2 ± 0.5, 7.7 ± 0.4, and 7.4 ± 0.4 mm, respectively. After 24 hours, the radii of curvature reached 6.8 ± 0.1, 6.6 ± 0.3, 7.6 ± 0.1, and 7.4 ± 0.2 mm, respectively. The kinetics of the deswelling process in medium II follow a hyperbolic curve. Considering a CCT of 506 μm at T12, we assume that a time interval of 12 hours in medium II might be enough for clinical purposes. This result might help to keep storage in medium II as short as possible to escape potential toxic effects of dextran in medium II. The radius of curvature does not seem to change within 24 hours for all measured surfaces.

Preformed particle gels for enhanced oil recovery

This study refers to the synthesis of new advanced preformed particle gels (PPGs) based on 2-acrylamido-2-methylpropane sulfonic acid (AMPS), Polyvinyl Pirrolidone (PVP) and bentonite clay. For the synthesis, [Formula: see text], [Formula: see text]-methylenebisacrylamide was used as crosslinker and ammonium persulphate as initiator. As a consequence of the inclusion of clay into the polymer matrix and the intercalation of AMPS between the layers as well as the presence of hydrophilic interactions occurring between partners, the final PPGs possessed greater swelling degrees, slower de-swelling process, high thermal stability and enhanced mechanical properties in comparison with pure PPG.

In-air fast response and high speed jumping and rolling of a light-driven hydrogel actuator

Stimuli-responsive hydrogel actuators have promising applications in various fields. However, the typical hydrogel actuation relies on the swelling and de-swelling process caused by osmotic-pressure changes, which is slow and normally requires the presence of water environment. Herein, we report a light-powered in-air hydrogel actuator with remarkable performances, including ultrafast motion speed (up to 1.6 m/s), rapid response (as fast as 800 ms) and high jumping height (~15 cm). The hydrogel is operated based on a fundamentally different mechanism that harnesses the synergetic interactions between the binary constituent parts, i.e. the elasticity of the poly(sodium acrylate) hydrogel, and the bubble caused by the photothermal effect of the embedded magnetic iron oxide nanoparticles. The current hydrogel actuator exhibits controlled motion velocity and direction, making it promising for a wide range of mobile robotics, soft robotics, sensors, controlled drug delivery and other miniature device applications.

Effect of surfactants on swelling capacity and kinetics of alginate-chitosan/CNTs hydrogel

Nanocomposite hydrogels of alginate-chitosan matrix with nanofillers, functionalized multi-walled carbon nanotubes (COOH-MWCNTs) were first time synthesized in cationic, anionic, mixture of cationic and anionic surfactants and in the absence of surfactants by employing solution casting method. Whole process of synthesis was carried out under greener source of heating i.e., ultrasonic waves. Synthesized films were evaluated by Fourier transform infrared spectroscopy and scanning electron microscopy which reveal uniform dispersion of nanofillers in matrix. Synthesized hydrogels were also newly explored for swelling capacity. Swelling ratio of hydrogels was measured in distilled water, saline solutions and in solutions of different pH. Swelling pattern of prepared films indicates that these materials are very stable and can show best performance in different pH and kinds of solutions. Effect of concentration ratio of nanofillers to matrix and nature of surfactants on swelling ability was also appraised and indicated that trace amount of nanofillers gives fascinating results. Process of swelling and deswelling of synthesized films was taken place by super case-II transport mechanism, which is effected by amount of nanofillers and nature of surfactant.

Improving the wettability and antiprotein adsorption property of PDMS by swelling–deswelling approach

In order to improve the wettability and antiprotein adsorption property of PDMS, heptamethyltrisiloxane (a well-known superspreader) was coated onto the PDMS substrates by a swelling–deswelling process. PDMS films were first immersed in heptamethyltrisiloxane solution mixtures to coat heptamethyltrisiloxane onto PDMS. During the deswelling process, the hydrophobic siloxane group of the superspreader heptamethyltrisiloxane was trapped in the PDMS matrix, while the hydrophilic group EO was exposed to the surface. In this manner, heptamethyltrisiloxane was finally coated on the PDMS surface via swelling–deswelling process. Contact angle measurements, optical property analyses, X-ray photoelectron spectroscopy, and atomic force microscopy were used to confirm that durable hydrophilic and transparent PDMS surfaces were successfully obtained. The PDMS surface wettability could be adjusted by tuning the solubility parameters of the solution mixture. Additionally, antiprotein adsorption property was investigated and the result indicated the heptamethyltrisiloxane was tethered onto the PDMS surface. The swelling–deswelling method can be applied for the modification of other crosslinked polymers to obtain antifouling surfaces and functional materials for biomedical applications. A superspreading surfactant (Silwet-L77) was coated onto the PDMS surface by the swelling–deswelling process, to improve its hydrophilicity and antiprotein adsorption properties.

Matrix-Assisted Regulation of Antimicrobial Properties: Mechanistic Elucidation with Ciprofloxacin-Based Polymeric Hydrogel Against Vibrio Species.

The design of a new drug material through modification of some well-known antibiotics to combat pathogenic bacteria must include a complete understanding of matrix regulation because the human body consists of primarily three types of matrices, that is, solid, semisolid, and liquid, all of which have a tendency to regulate antibacterial efficacy along with the bactericidal mechanism of several antimicrobial agents. Herein, matrix-dependent action of ciprofloxacin-based polymeric hydrogel scaffold was explored against a new species of Vibrio, namely, Vibrio chemaguriensis Iso1 ( V. chemaguriensis), which is resistant to most of the common antibiotics and possess genes that can be linked to pathogenicity. Ciprofloxacin was attached to the polymeric system consisting of hydrophilic polyethylene glycol methyl ether methacrylate (PEGMA) and zwitterionic sulphabetaine methacrylate (SBMA) with an antifouling nature via covalent linkage leading to effective polymer antibiotic conjugates (PACs) with linear and hyperbranched architectures. The hyperbranched PAC was transformed to a polymeric gel exhibiting greater antibacterial efficacy in solid matrix than that of the liquid one with a complete bactericidal effect and rod to spherical switching of bacterial cell followed by chain formation via "dual" contact activity and release mechanism through sustained removal of thiol-terminated ciprofloxacin fragment along with an equilibrium swelling and deswelling process. Lower killing efficacy was displayed in the liquid matrix with an intact cell morphology that is due to lack of forced contact between the cell wall and gel surface as well as entrapment of released bioactive fragment via an additional thick exopolysaccharide (EPS) layer, which represents a great challenge to modern medical sciences.

Novel Hydrogel-Advanced Modified Clay Nanocomposites as Possible Vehicles for Drug Delivery and Controlled Release.

Present study refers to the synthesis of new advanced materials based on poly(methacrylic acid) (PMAA) with previously reported own advanced modified clays by edge covalent bonding. This will create the premises to obtain nanocomposite hydrogels with combined hydrophilic-hydrophobic behavior absolutely necessary for co-delivery of polar/nonpolar substances. For the synthesis, N,N’-methylenebisacrylamide was used as cross-linker and ammonium persulphate as initiator. As a consequence of the inclusion of clay into the polymer matrix and the intercalation of PMAA between the layers as well as the presence of hydrophobic interactions occurred between partners, the final hydrogel nanocomposites possessed greater swelling degrees, slower de-swelling process and enhanced mechanical properties depending on the clay type in comparison with pure hydrogel. In vitro MTS ([3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt]) colorimetric assay showed that direct exposure with PMMA-clay-based constructs did not affect cell viability and proliferation in time (24 and 48 h) on either normal or adenocarcinoma cell lines.

Deformation velocity imaging using optical coherence tomography and its applications to the cornea.

Optical coherence tomography (OCT) can monitor human donor corneas non-invasively during the de-swelling process following storage for corneal transplantation, but currently only resultant thickness as a function of time is extracted. To visualize and quantify the mechanism of de-swelling, we present a method exploiting the nanometer sensitivity of the Fourier phase in OCT data to image deformation velocities. The technique was demonstrated by non-invasively showing during de-swelling that osmotic flow through an intact epithelium is negligible and removing the endothelium approximately doubled the initial flow at that interface. The increased functional data further enabled the validation of a mathematical model of the cornea. Included is an efficient method of measuring high temporal resolution (1 minute demonstrated) corneal thickness, using automated collection and semi-automated graph search segmentation. These methods expand OCT capabilities to measure volume change processes for tissues and materials.

Role of the Endothelial Layer in the Deswelling Process of Organ-Cultured Human Corneas Before Transplantation.

Before corneal transplant surgery, a deswelling process of organ-cultured corneas is required. This study compares the deswelling kinetics of corneas with an intact endothelial cell layer and disrupted or removed endothelium by measuring central corneal thickness (CCT) over time using anterior segment spectral domain optical coherence tomography. Ten donor pairs were cultured in organ culture. The right and left corneas were alternately assigned to one of 2 deswelling groups. Deswelling in the first group [endothelial group (EG)] was induced using a medium with dextran 5%. Corneas of the second group [nonendothelial group (NEG)] were deprived of their endothelial cell layer by trypsinization and were then placed in the same deswelling medium. CCT (mean ± SD) was measured by anterior segment spectral domain optical coherence tomography before deswelling (0 hours) and after 1, 2, 3, 6, 12, 24, 48, 72, and 144 hours. Deswelling kinetics was analyzed through the nonlinear platform in SAS/JMP11 Pro. Before deswelling, CCT was 1071.0 μm (±129.6 μm) and 1133.8 μm (±124.3 μm) in the EG and NEG, respectively. Minimum corneal thickness was obtained after 24 hours in the EG (531.9 ± 47.5 μm) and 6 hours in the NEG (645 ± 81.2 μm). CCT was significantly (P < 0.01) higher in the NEG than EG after more than 6 hours. Corneal dehydration after organ culture seems to be a multifactorial process, which not only depends on osmotic effects of the deswelling compound but also requires the presence of an intact endothelial cell layer.

Evaluation of poly (vinyl alcohol) based cryogel–zinc oxide nanocomposites for possible applications as wound dressing materials

In this investigation cryogels composed of poly (vinyl alcohol) (PVA) were prepared by repeated freeze thaw method followed by in situ precipitation of zinc oxide nanoparticles within the cryogel networks. Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX) were used to characterize the nanocomposites. The morphologies of native PVA cryogels and PVA cryogel-ZnO nanocomposites were observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) techniques. The SEM analysis suggested that cryogels show a well-defined porous morphology whereas TEM micrographs revealed the presence of nearly spherical and well separated zinc oxide nanoparticles with diameter<100nm. XRD results showed all relevant Bragg's reflections for crystal structure of zinc oxide nanoparticles. Thermo gravimetric-differential thermal analysis (TG-DTA) was conducted to evaluate thermal stability of the nanocomposites. Mechanical properties of nanocomposites were determined in terms of tensile strength and percent elongation. Biocompatible nature was ascertained by anti-haemolytic activity, bovine serum albumin (blood protein) adsorption and in vitro cytotoxicity tests. The prepared nanocomposites were also investigated for swelling and deswelling behaviours. The results revealed that both the swelling and deswelling process depend on the chemical composition of the nanocomposites, number of freeze-thaw cycles, pH and temperature of the swelling medium. The developed biocompatible PVA cryogel-ZnO nanocomposites were also tested for antibacterial activities against both Gram-negative and Gram-positive bacteria.