Calcium Alginate Hydrogel Research Articles

Separation of no-carrier-added 203Pb, a surrogate radioisotope, from proton irradiated natTl2CO3 target using calcium alginate hydrogel beads

Abstract 203Pb is a promising radioisotope in the field of medical science as an imaging surrogate of 212Pb. In the present investigation 203Pb was produced by proton irradiation of natural Tl2CO3 target and was separated from the bulk Tl target using calcium alginate (CA) hydrogel beads with a high separation factor (3.8×104 at 10−3 M HNO3). During the separation process 203Pb was encapsulated in CA beads and desorption of the radioisotope could only be achieved in 1M HNO3. Possibility of Tl uptake was also checked in Fe doped CA (Fe-CA) beads after oxidation of Tl(I) to Tl(III) by sodium bismuthate. No significant uptake of Tl(III) was noticed in the Fe-CA beads. The matrix is therefore suitable for isolation of 203Pb from the target as well as its storage in the bead for therapeutic as well as diagnostic purpose.

Development of zirconia nanoparticles-decorated calcium alginate hydrogel fibers for extraction of organophosphorous pesticides from water and juice samples: Facile synthesis and application with elimination of matrix effects

In this research, novel zirconia nanoparticles-decorated calcium alginate hydrogel fibers (ZNCAHF) were synthesized through a simple, green procedure. ZNCAHF were used as an adsorbent in the micro–solid-phase extraction (MSPE) of methyl parathion (MP), fenitrothion (FT) and malathion (MT) as model pesticides prior to gas chromatography-mass spectroscopic detection (GC–MS). The composition and morphology of the prepared fiber were characterized by Fourier transform-infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray diffraction (EDX), and differential scanning calorimetry (DSC). Various parameters affecting fabrication of the fiber (weight ratio of components) and relative extraction recovery (pH, amount of adsorbent, extraction time, salt addition, and desorption conditions) were investigated and optimized. Under optimized conditions, the calibration curves were obtained in the concentration range of 0.01–500ngmL−1 with regression coefficients between 0.9997 and 0.9999. The limits of detection (LOD) (S/N=3) and limits of quantification (LOQ) (S/N=10) of the method ranged from 0.001 to 0.004ngmL−1 and 0.003 to 0.012ngmL−1, respectively. The intra-day and inter-day relative standard deviations (RSDs) were 2.2–5.9% and 3.2–7.8%, respectively. The applicability of the fabricated adsorbent was investigated by extraction of selected organophosphorous pesticides (OPPs) from real samples of juice and water. The obtained relative recoveries were in the range of 90.6-105.4%, demonstrating elimination of matrix effects which can be attributed to the remarkable affinity of OPPs toward ZNCAHF.

Preparation and characterization of protein molecular imprinted calcium alginate hydrogel film with controllable thickness

Bovine serum albumin (BSA) imprinted calcium alginate (CaAlg MIP) hydrogel film was prepared using BSA as template molecule, sodium alginate (NaAlg) as the functional monomer, and CaCl2 as the ionic cross-linker. The thickness of the film was controlled by a glass rod enlaced with brass wires. The relationship between copper wire diameter and the thickness of CaAlg MIP was investigated. SEM, laser scanning confocal microscope and 3D ultra-depth three-dimensional microscope were used to characterize the CaAlg MIP. The mechanical properties of the wet CaAlg MIP prepared with different concentrations of NaAlg were investigated. Circular dichroism (CD) was used to characterize the conformation of the eluted BSA. The influence of different thickness and different eluants on the adsorption capacity of CaAlg MIP was discussed. The results showed that CaAlg MIP adsorbed more BSA than CaAlg NIP. There was no change of the conformation of protein during the preparing and eluting process. The CaAlg MIP can be prepared by a fast, low-cost and environmental friendly method in aqueous solution in the absence of any toxic surfactant or organic solvent, which would find its potential applications in the fields of cell culture and tissue engineering.

Electrochemical Hydrogel Lithography of Calcium-Alginate Hydrogels for Cell Culture.

Here we propose a novel electrochemical lithography methodology for fabricating calcium-alginate hydrogels having controlled shapes. We separated the chambers for Ca2+ production and gel formation with alginate with a semipermeable membrane. Ca2+ formed in the production chamber permeated through the membrane to fabricate a gel structure on the membrane in the gel formation chamber. When the calcium-alginate hydrogels were modified with collagen, HepG2 cells proliferated on the hydrogels. These results show that electrochemical hydrogel lithography is useful for cell culture.

Encapsulation optimization of lemon balm antioxidants in calcium alginate hydrogels

Calcium alginate hydrogel beads were used to encapsulate lemon balm extract. Chitosan layer was used to investigate the effect of hydrogel coating. To determine the interactions of antioxidant compounds of extract with encapsulation materials and its stability, microstructure of hydrogel beads was thoroughly monitored using scanning electron microscopy and Fourier transform infrared (FTIR). Total polyphenols content and antiradical activity of lemon balm extract were also evaluated before and after encapsulation. Three significant parameters (lemon balm extract, sodium alginate, and calcium chloride concentrations) were optimized by response surface methodology to obtain maximum encapsulation efficiency. The FTIR spectra showed no interactions between extract and polymers as there were no new band in spectra of alginate hydrogel after encapsulation of active compounds of lemon balm extract. The antioxidant activity of lemon balm extract did not change after encapsulation. Therefore, it was found that alginate is a suitable material for encapsulation of natural antioxidants. Sodium alginate solution concentration, 1.84%, lemon balm extract concentration, 0.4%, and calcium chloride concentration, 0.2% was determined to be the optimum condition to reach maximum encapsulation efficiency.

Alginate Microfiber System for Expansion and Direct Differentiation of Human Embryonic Stem Cells.

Pluripotent human embryonic stem cells (hESCs) are a potential renewable cell source for regenerative medicine and drug testing. To obtain adequate cell numbers for these applications, there is a need to develop scalable cell culture platforms to propagate hESCs. In this study, we encapsulated hESCs in calcium alginate microfibers as single cells, for expansion and differentiation under chemically defined conditions. hESCs were suspended in 1% (w/v) alginate solution at high cell density (>10(7) cells/mL) and extruded at 5 m/min into a low calcium concentration bath (10 mM) for gelation. Mild citrate buffer (2.5 mM), which did not affect hESCs viability, was used to release the cells from the calcium alginate hydrogel. Encapsulation as single cells was critical, as this allowed the hESCs to grow in the form of relatively small and uniform aggregates. This alginate microfiber system allowed for expansion of an hESC line, HUES7, for up to five passages while maintaining pluripotency. Immunohistochemistry, polymerase chain reaction, and other analyses showed that passage 5 (P5) HUES7 cells expressed proteins and genes characteristic of pluripotent stem cells, possessed normal karyotype, and were able to form representative tissues of the three embryonic germ layers in vitro and in vivo. Encapsulated HUES7 cells at P5 could also be induced to directly differentiate into liver-like cells. Collectively, our experiments show that the alginate microfiber system can be used as a three-dimensional cell culture platform for long-term expansion and differentiation of hESCs under defined conditions.

BSA imprinted polyethylene glycol grafted calcium alginate hydrogel microspheres

ABSTRACTPolyethylene glycol grafted calcium alginate hydrogel microspheres are synthesized by ring‐opening and addition reaction of epoxy chloropropane. FTIR, 13C NMR, optical microscope, SEM, TG, and DSC are used for characterization. Swelling behaviors are studied and it is found that polyethylene glycol grafted calcium alginate microspheres are improved in anti‐swelling properties. Protein‐imprinted polyethylene glycol grafted calcium alginate hydrogel microspheres exhibit enhanced specific rebinding quantity (11.16 mg/g) and selective recognition properties (4.71 against BHb), towards target molecule in the presence of competing protein, compared with that of the unmodified samples (4.96 mg/g and 1.75, respectively). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43617.

Detoxification of Hg(II) from aqueous and enzyme media: Pristine vs. tailored calcium alginate hydrogels

Calcium alginate (CA) hydrogels were tailored using phenolic compounds (PC) like, thymol, morin, catechin, hesperidin, during their preparation. The PC incorporated gels show modified surface features as indicated by scanning electron microscopic images (SEM). The rheological studies show that excepting the hesperidin incorporated gels all the other kinds including calcium alginate pristine have similar mechanical strength. The hesperidine incorporated CA gels had the maximum capacity to adsorb Hg. The Freundlich adsorption isotherms show higher values of adsorption capacity for all PC incorporated CA beads than the pristine CA (PCA). The hesperidin incorporated CA gels were found to show the best adsorption condition at neutral pH and an optimum contact time of 2.5h at 25°C. Considering the possibility of ingested Hg detoxification from human alimentary tract, the hesperidin and morin incorporated CA beads were further modified through incorporation of cod liver oil as the digestion time of fat in stomach is higher. In vitro uptake capacities of Hg in pepsin and pancreatin containing enzyme media were studied with hesperidin and morin incorporated beads and their corresponding fat incorporated beads also. In the pepsin medium, there was no uptake by hesperidin and fat-hesperidin incorporated beads, which is possibly due to the higher acidity of the medium. But in pancreatin medium Hg was taken up by both kinds of beads. Morin and morin-fat incorporated beads were efficient to uptake Hg from both the pepsin and pancreatin medium. The tailored CA beads may therefore serve as efficient scaffolds to rescue Hg ingested individuals.

Differentiation Induction of Mouse Neural Stem Cells in Hydrogel Tubular Microenvironments with Controlled Tube Dimensions.

In this paper, a tubular 3D microenvironment created in a calcium alginate hydrogel microtube with respect to the effect of scaffold dimensions on the differentiation of mouse neuronal stem cells (mNSCs) is evaluated. Five types of hydrogel microtubes with different core diameters (≈65-200 μm) and shell thicknesses (≈30-110 μm) are fabricated by using a double coaxial microfluidic device, and differentiation of encapsulated mNSCs is induced by changing the growth medium to the differentiation medium. The influence of the microtube geometries is examined by using quantitative real-time polymerase chain reaction and fluorescent immunocytochemistry. The analyses reveal that differences in microtube thickness within 30-110 μm affected the relative Tuj1 expression but do not affect the morphology of encapsulated mNSCs. The diameters of cores influence both the relative Tuj1 expression and morphology of the differentiated neurons. It is found that the tubular microenvironment with a core diameter of less than ≈100 μm contributes to forming highly viable and aligned neural tissue. The tubular microenvironment can provide an effective method for constructing microfiber-shaped neural tissues with geometrically controlled differentiation induction.

Performance evaluation of nanoclay enriched anti-microbial hydrogels for biomedical applications.

A major factor contributing to the failure of orthopedic and orthodontic implants is post-surgical infection. Coating metallic implant surfaces with anti-microbial agents has shown promise but does not always prevent the formation of bacterial biofilms. Furthermore, breakdown of these coatings within the human body can cause release of the anti-microbial drugs in an uncontrolled or unpredictable fashion. In this study, we used a calcium alginate and calcium phosphate cement (CPC) hydrogel composite as the base material and enriched these hydrogels with the anti-microbial drug, gentamicin sulfate, loaded within a halloysite nanotubes (HNTs). Our results demonstrate a sustained and extended release of gentamicin from hydrogels enriched with the gentamicin-loaded HNTs. When tested against the gram-negative bacteria, the hydrogel/nanoclay composites showed a pronounced zone of inhibition suggesting that anti-microbial doped nanoclay enriched hydrogels can prevent the growth of bacteria. The release of gentamicin sulfate for a period of five days from the nanoclay-enriched hydrogels would supply anti-microbial agents in a sustained and controlled manner and assist in preventing microbial growth and biofilm formation on the titanium implant surface. A pilot study, using mouse osteoblasts, confirmed that the nanoclay enriched surfaces are also cell supportive as osteoblasts readily, proliferated and produced a type I collagen and proteoglycan matrix.

Calcium alginate hydrogel beads with high stiffness and extended dissolution behaviour

Alginate hydrogel bead has been widely explored as a vehicle for controlled delivery application due to its non-toxicity, renewability, and ease of formation. However, alginate hydrogel beads are known to have a low stiffness, i.e., Young modulus <1MPa, and a short dissolution time of between 1h and 2h in gastrointestinal fluid. This study aimed to fabricate calcium alginate hydrogel beads with desired properties like high stiffness and extended dissolution behaviour. A temperature-controlled extrusion–dripping method incorporating an immiscible interphase column was used to produce the ultra-high concentration (UHC) calcium hydrogel beads directly from unmodified alginate solution. The UHC beads have an extraordinary internal structure with thick calcium-alginate matrices and large pores in between the matrices. The Young’s modulus value of UHC calcium alginate beads was 3.6MPa, which was approximately 8times higher than the normal calcium alginate beads. The release profile for the model drug (i.e., methylene blue) encapsulated in UHC beads was found to be extended to 4h at 80% of drug release (t80). The kinetics of drug release fitted well with the Korsmeyer–Peppas model (r2⩾0.99) and followed the non-Fickian mechanism. These findings show that the preparation of calcium alginate beads featuring high stiffness and extended dissolution profile can be achieved without any chemical modification or additives. The UHC calcium alginate bead holds excellent promise as an encapsulation carrier of drugs or food used in controlled delivery applications.

In situ pore-forming alginate hydrogel beads loaded with in situ formed nano-silver and their catalytic activity.

An aqueous mixture of sodium carbonate (Na2CO3) and sodium alginate (Na-ALG) was added dropwise into an aqueous solution of Ca(NO3)2, leading to the formation of calcium alginate (Ca-ALG) hydrogel beads. Meanwhile Na2CO3 as a pore-forming precursor was transformed in situ into CaCO3 nanoparticles (CaCO3 NPs). SEM images show that CaCO3 NPs aggregates with a size of ∼10 μm were uniformly distributed in the Ca-ALG hydrogel beads. After subsequent erosion using acetic acid, Ca-ALG hydrogel beads with a uniform microporous structure were obtained. The porosity and specific surface area of such in situ pore-formed hydrogel beads are 16 and 14 times higher than those of the beads prepared in the absence of Na2CO3. Additionally, their porous structure can be modulated by varying the amount of Na2CO3. The obtained porous Ca-ALG hydrogel beads were further immersed into an aqueous solution of AgNO3. Under UV irradiation, the Ag(+) ions adsorbed in the Ca-ALG were in situ reduced to Ag nanoparticles (Ag NPs). SEM and TEM images show that Ag NPs with a size of ∼10 nm were uniformly distributed in the matrix of the hydrogel beads. The loading amount of Ag in the beads can also be modulated by varying the amount of Na2CO3. Furthermore, the resultant Ca-ALG beads loaded with Ag NPs (Ag/Ca-ALG) were used as catalysts. Their catalytic activity was evaluated by using the reduction reaction of 4-nitrophenol as a model reaction. The rate constant of the reaction in the presence of dry porous Ag/Ca-ALG beads was found to be 36 times higher than that in the presence of beads prepared in the absence of Na2CO3. Such a high catalytic efficiency can be attributed to their porous structure and consequent high Ag-loading capacity.

Enzymatic Biosensors Based on Electrodeposited Alginate Hydrogels

In the current work, we study the use of electrodeposited calcium alginate hydrogels in the development of enzymatic biosensors. Alginate electrodeposition involves the rupture of CaCO3 particles by protons from water electrolysis into Ca2+ and HCO3−. The released calcium ions cross-link alginate forming the hydrogel. Horseradish peroxidase (HRP, used as model enzyme) was electrodeposited on screen printed gold electrode (SPGE) and the activity of the enzyme was analyzed amperometrically using 3,3’,5,5’-Tetramethylbenzidine (TMB) as the mediator. The obtained gels showed good adherence to the electrode surface and stability, and did not extend more than 0.5mm far from the desired area of deposition, allowing high control of the electrodeposition. The biosensors showed good analytical characteristics to H2O2 determination, with short response times, sensitivity, low limit of detection and long lineal range.

Biochemical Monitoring of Spinal Cord Injury by FT-IR Spectroscopy--Effects of Therapeutic Alginate Implant in Rat Models.

Spinal cord injury (SCI) induces complex biochemical changes, which result in inhibition of nervous tissue regeneration abilities. In this study, Fourier-transform infrared (FT-IR) spectroscopy was applied to assess the outcomes of implants made of a novel type of non-functionalized soft calcium alginate hydrogel in a rat model of spinal cord hemisection (n = 28). Using FT-IR spectroscopic imaging, we evaluated the stability of the implants and the effects on morphology and biochemistry of the injured tissue one and six months after injury. A semi-quantitative evaluation of the distribution of lipids and collagen showed that alginate significantly reduced injury-induced demyelination of the contralateral white matter and fibrotic scarring in the chronic state after SCI. The spectral information enabled to detect and localize the alginate hydrogel at the lesion site and proved its long-term persistence in vivo. These findings demonstrate a positive impact of alginate hydrogel on recovery after SCI and prove FT-IR spectroscopic imaging as alternative method to evaluate and optimize future SCI repair strategies.

One-year follow-up results from AUGMENT-HF: a multicentre randomized controlled clinical trial of the efficacy of left ventricular augmentation with Algisyl in the treatment of heart failure.

AUGMENT-HF was an international, multicentre, prospective, open-label, randomized, controlled evaluation testing the hypothesis that Algisyl (injectable calcium alginate hydrogel) is superior to standard medical therapy (SMT) for improving functional capacity and clinical outcomes in patients with advanced heart failure (HF). We previously reported results following 6 months of follow-up. This report presents the results from 1 year of extended follow up for this clinical trial. We enrolled 78 patients with advanced HF, randomized (1:1), to Algisyl with SMT or SMT alone as previously reported. Patient inclusion criteria were LVEF ≤35%, peak VO2 of 9.0-14.5 mL/min/kg and LV end-diastolic diameter (LVEDD) index 30-40 mm/m(2) (LVEDD/body surface area). Patients must have been on stable, evidence-based therapy for HF. A total of 58 patients, mean age 62.3 ± 9.6 years, with ischaemic (57.7%) or non-ischaemic (42.3%) HF completed 12 months of follow-up. Treatment with Algisyl was associated with improved peak VO2 at 12 months; treatment effect vs. control of +2.10 mL/kg/min (95% confidence interval 0.96-3.24, P < 0.001). Statistically significant improvements were observed for VO2 at anaerobic threshold, 6-min walk test distance, and NYHA functional class (all P < 0.001). Through 12 months of follow-up there were 4 (10.5%) deaths in the control group and 9 (22.5%) deaths in the Algisyl group. Algisyl in addition to SMT was more effective than SMT alone for providing sustained 1-year benefits in exercise capacity, symptoms, and clinical status for patients with advanced HF. These data support larger clinical evaluations of this novel therapy.

Digital Microfluidic System with Vertical Functionality

Digital (droplet) microfluidics (DµF) is a powerful platform for automated lab-on-a-chip procedures, ranging from quantitative bioassays such as RT-qPCR to complete mammalian cell culturing. The simple MEMS processing protocols typically employed to fabricate DµF devices limit their functionality to two dimensions, and hence constrain the applications for which these devices can be used. This paper describes the integration of vertical functionality into a DµF platform by stacking two planar digital microfluidic devices, altering the electrode fabrication process, and incorporating channels for reversibly translating droplets between layers. Vertical droplet movement was modeled to advance the device design, and three applications that were previously unachievable using a conventional format are demonstrated: (1) solutions of calcium dichloride and sodium alginate were vertically mixed to produce a hydrogel with a radially symmetric gradient in crosslink density; (2) a calcium alginate hydrogel was formed within the through-well to create a particle sieve for filtering suspensions passed from one layer to the next; and (3) a cell spheroid formed using an on-chip hanging-drop was retrieved for use in downstream processing. The general capability of vertically delivering droplets between multiple stacked levels represents a processing innovation that increases DµF functionality and has many potential applications.

General Approach to the Immobilization of Glycoenzyme Chains Inside Calcium Alginate Beads for Bioassay.

A general method to obtain the efficient entrapment of mixtures of glycoenzymes in calcium alginate hydrogel is proposed in this paper. As a proof of principle, three glycoenzymes acting in series (trehalase, glucose oxidase, and horseradish peroxidase) have been coimmobilized in calcium alginate beads. The release of the enzymes from the hydrogel mesh (leakage) is avoided by exploiting the enzyme's aggregation induced by the concanavalin A. The aggregation process has been monitored by dynamic light scattering technique, while both enzyme encapsulation efficiency and leakage have been quantified spectrophotometrically. Obtained data show an encapsulation efficiency above 95% and a negligible leakage from the beads when enzyme aggregates are larger than 300 nm. Operational stability of "as prepared" beads has been largely improved by a coating of alternated shells of polycation poly(diallyldimethylammonium chloride) and of alginate. As a test for the effectiveness of the overall procedure, analytical bioassays exploiting the enzyme-containing beads have been developed for the optical determination of glucose and trehalose, and limit of detection values of 0.2 and of 40 μM, respectively, have been obtained.

Cell sheets prepared via gel–sol transition of calcium RGD–alginate

The formation of layered tissues through the use of cell sheet harvesting has recently emerged as a potentially viable approach for clinical tissue engineering applications. Since the demonstration of effective cell sheet formation using temperature responsive substrates, a number of different stimuli have been utilized to facilitate cell sheet detachment. Each approach has differing advantages and disadvantages. Herein we demonstrate the ability of calcium alginate hydrogels to function as an effective substrate for cell sheet formation. By conjugating the integrin binding peptide sequence RGD to the alginate and crosslinking it with calcium ions, the hydrogel formed supported the attachment and growth of both 3T3 fibroblasts and human corneal epithelial cells (HCECs). Once the cells had grown to confluence, exposing the calcium alginate to the chelating agent citrate caused the release of a consolidated cell sheet. When HCEC sheets were stacked, the cell layers adhered to each other and the cells began to integrate. Statement of significanceHerein we describe a simple and inexpensive process for creating cell sheets using the ability of calcium alginate hydrogels to be dissolved under mild conditions. The alginate was first modified to possess cell attachment sites and in this demonstration of feasibility we employed an RGD peptide, but other peptides could be readily attached. The modified alginate was then formed into stable hydrogels through a drying and re-hydration step, and used as a substrate to grow confluent cell sheets of human corneal epithelial cells and 3T3 fibroblasts as examples. The cell sheets were released through chelating the calcium using citrate. The cell–cell connections were retained following this release and the cell sheets interconnect and grew following being stacked.

Paper-Based Electrodeposition Chip for 3D Alginate Hydrogel Formation

Hydrogel has been regarded as one significant biomaterial in biomedical and tissue engineering due to its high biocompatibility. This paper proposes a novel method to pattern calcium alginate hydrogel in a 3D way via electrodeposition process based on a piece of paper. Firstly, one insulating paper with patterned holes is placed on one indium tin oxide (ITO) glass surface, which is put below another ITO glass. Then, 1% sodium alginate solution with 0.25% CaCO3 nano particles is filled between these two glasses. In the bottom glass, patterns of electrodes followed patterns of holes on the insulating layer. Hydrogel forms on patterned electrodes when electrochemical potential is applied due to electrodeposition. The experiments demonstrate that the pattern of alginate hydrogels follows the pattern of electrodes exactly. In addition, the hydrogel’s height is controllable by applied potential and reaction time. An equivalent circuit model and a hydrogel growth model have been built to predict the electrodeposition current and hydrogel’s growth. This method for gel formation is easy and cheap since the main material is one piece of insulated paper, which provides an easy and controllable method for 3D hydrogel patterning.

In-situ assembly of Ca-alginate gels with controlled pore loading/release capability.

Development of tailor-made porous polymer scaffolds acting as a temporary tissue-construct for cellular organization is of primary importance for tissue engineering applications. Control over the gel porosity is a critical issue due to the need for cells to proliferate and migrate and to ensure the transport of nutrition and metabolites. Gel loading with bioactive molecules is desired for target release of soluble signals to guide cell function. Calcium-alginate hydrogels are one of the most popular gels successfully utilized as polymer scaffolds. Here we propose a benchtop approach to design porous alginate gels by dispersion of CaCO3 vaterite crystals in sodium alginate followed by the crystal elimination. CaCO3 crystals play a triple role being (i) cross-linkers (a source of calcium ions to cross-link gel network), (ii) pore-makers (leaching of crystals retains the empty pores), and (iii) reservoirs with (bio)molecules (by molecule preloading into the crystals). Pore dimensions, interconnectivity, and density can be adjusted by choosing the size, concentration, and packing of the sacrificial CaCO3 crystals. An opportunity to load the pores with biomolecules was demonstrated using FITC-labeled dextrans of different molecular masses from 10 to 500 kDa. The dextrans were preloaded into CaCO3 vaterite crystals, and the subsequent crystal removal resulted in encapsulation of dextrans inside the pores of the gel. The dextran release rate from the gel pores depends on the equilibration of the gel structure as concluded by comparing dextran release kinetics during gelation (fast) and dextran diffusion into the performed gel (slower). Macromolecule binding to the gel is electrostatically driven as found for lysozyme and insulin. The application of porous gels as scaffolds potentially offering biomacromolecule encapsulation/release performance might be useful for alginate gel-based applications such as tissue engineering.