Probiotic Encapsulation: Bead Design Improves Bacterial Performance during In Vitro Digestion

The stability and release properties of all bioactive capsules are strongly related to the composition of the wall material. This study aimed to evaluate the effect of the wall materials during the encapsulation process by ionotropic gelation on the viability of Lactobacillus fermentum K73, a lactic acid bacterium that has hypocholesterolemia probiotic potential. A response surface methodology experimental design was performed to improve bacterial survival during the synthesis process and under simulated gastrointestinal conditions by tuning the wall material composition (gelatin 25% w/v, sweet whey 8% v/v, and sodium alginate 1.5% w/v). An optimal mixture formulation determined that the optimal mixture must contain a volume ratio of 0.39/0.61 v/v sweet whey and sodium alginate, respectively, without gelatin, with a final bacterial concentration of 9.20 log10 CFU/mL. The mean particle diameter was 1.6 ± 0.2 mm, and the experimental encapsulation yield was 95 ± 3%. The INFOGEST model was used to evaluate the survival of probiotic beads in gastrointestinal tract conditions. Upon exposure to in the vitro conditions of oral, gastric, and intestinal phases, the encapsulated cells of L. fermentum decreased only by 0.32, 0.48, and 1.53 log10 CFU/mL, respectively, by employing the optimized formulation, thereby improving the survival of probiotic bacteria during both the encapsulation process and under gastrointestinal conditions compared to free cells. Beads were characterized using SEM and ATR-FTIR techniques.

Evaluation of curcumin-loaded chitosan nanoparticles for wound healing activity

Background and purpose

Wound healing is a biological process that can be difficult to manage clinically. In skin wound healing, the interaction of many cells, growth factors, and cytokines reveals an outstanding biological function mechanism. Wound healing that occurs naturally restores tissue integrity, however, it is usually restricted to wound repair. Curcumin synthesised in a chitosan matrix can be used to heal skin sores.

Experimental approach

The ionotropic gelation procedure required crosslinking chitosan with a tripolyphosphate (TPP) crosslinker to generate curcumin nanoparticles encapsulated in chitosan.

Key results

The nanoparticles were between 200 and 400 nm in size, with a strong positive surface charge and good entrapment efficacy, according to SEM and TEM investigations. Curcumin and chitosan compatibility was investigated using FTIR spectroscopy. All batches showed consistent drug release, with the F5 batch having the highest curcumin release, at 75% after 16 hours. On L929 cells, scratch assays were utilised to assess wound healing. Wound closure with widths of 59 and 65 mm with curcumin and 45 and 78 mm with curcumin-loaded chitosan nanoparticles was seen after 24 and 48 hours of examination.

Conclusions

According to the findings, prepared curcumin chitosan nanoparticles are beneficial in healing skin damage.

Encapsulation of Pineapple Peel Extracts by Ionotropic Gelation Using Corn Starch, Weissella confusa Exopolysaccharide, and Sodium Alginate as Wall Materials

Phenolic compounds that are present in pineapple by-products offer many health benefits to the consumer; however, they are unstable to many environmental factors. For this reason, encapsulation is ideal for preserving their beneficial effects. In this work, extracts were obtained by the combined method of solid-state fermentation with Rhizopus oryzae and ultrasound. After this process, the encapsulation process was performed by ionotropic gelation using corn starch, sodium alginate, and Weissella confusa exopolysaccharide as wall material. The encapsulates produced presented a moisture content between 7.10 and 10.45% (w.b), a solubility of 53.06 ± 0.54%, and a wettability of 31.46 ± 2.02 s. The total phenolic content (TPC), antioxidant capacity of DPPH, and ABTS of the encapsulates were also determined, finding 232.55 ± 2.07 mg GAE/g d.m for TPC, 45.64 ± 0.9 µm Trolox/mg GAE for DPPH, and 51.69 ± 1.08 µm Trolox/mg GAE for ABTS. Additionally, ultrahigh performance liquid chromatography (UHPLC) analysis allowed us to identify and quantify six bioactive compounds: rosmarinic acid, caffeic acid, p-coumaric acid, ferulic acid, gallic acid, and quercetin. According to the above, using ionotropic gelation, it was possible to obtain microencapsulates containing bioactive compounds from pineapple peel extracts, which may have applications in the development of functional foods.

Novel Hydrogel Membranes Based on the Bacterial Polysaccharide FucoPol: Design, Characterization and Biological Properties

FucoPol, a fucose-rich polyanionic polysaccharide, was used for the first time for the preparation of hydrogel membranes (HMs) using Fe³⁺ as a crosslinking agent. This study evaluated the impact of Fe³⁺ and FucoPol concentrations on the HMs' strength. The results show that, above 1.5 g/L, Fe³⁺ concentration had a limited influence on the HMs' strength, and varying the FucoPol concentration had a more significant effect. Three different FucoPol concentrations (1.0, 1.75 and 2.5 wt.%) were combined with Fe³⁺ (1.5 g/L), resulting in HMs with a water content above 97 wt.% and an Fe³⁺ content up to 0.16 wt.%. HMs with lower FucoPol content exhibited a denser porous microstructure as the polymer concentration increased. Moreover, the low polymer content HM presented the highest swelling ratio (22.3 ± 1.8 g/g) and a lower hardness value (32.4 ± 5.8 kPa). However, improved mechanical properties (221.9 ± 10.2 kPa) along with a decrease in the swelling ratio (11.9 ± 1.6 g/g) were obtained for HMs with a higher polymer content. Furthermore, all HMs were non-cytotoxic and revealed anti-inflammatory activity. The incorporation of FucoPol as a structuring agent and bioactive ingredient in the development of HMs opens up new possibilities for its use in tissue engineering, drug delivery and wound care management.

Microencapsulation of a Pickering Oil/Water Emulsion Loaded with Vitamin D3

The ionotropic gelation technique was chosen to produce vitamin D3-loaded microparticles starting from oil-in-water (O/W) Pickering emulsion stabilized by flaxseed flour: the hydrophobic phase was a solution of vitamin D3 in a blend of vegetable oils (ω6:ω3, 4:1) composed of extra virgin olive oil (90%) and hemp oil (10%); the hydrophilic phase was a sodium alginate aqueous solution. The most adequate emulsion was selected carrying out a preliminary study on five placebo formulations which differed in the qualitative and quantitative polymeric composition (concentration and type of alginate selected). Vitamin D3-loaded microparticles in the dried state had a particle size of about 1 mm, 6% of residual water content and excellent flowability thanks to their rounded shape and smooth surface. The polymeric structure of microparticles demonstrated to preserve the vegetable oil blend from oxidation and the integrity of vitamin D3, confirming this product as an innovative ingredient for pharmaceutical and food/nutraceutical purposes.

Ionotropic Gelation and Chemical Crosslinking as Methods for Fabrication of Modified-Release Gellan Gum-Based Drug Delivery Systems

Hydrogels have a tridimensional structure. They have the ability to absorb a significant amount of water or other natural or simulated fluids that cause their swelling albeit without losing their structure. Their properties can be exploited for encapsulation and modified targeted drug release. Among the numerous natural polymers suitable for obtaining hydrogels, gellan gum is one gaining much interest. It is a gelling agent with many unique features, and furthermore, it is non-toxic, biocompatible, and biodegradable. Its ability to react with oppositely charged molecules results in the forming of structured physical materials (films, beads, hydrogels, nanoparticles). The properties of obtained hydrogels can be modified by chemical crosslinking, which improves the three-dimensional structure of the gellan hydrogel. In the current review, an overview of gellan gum hydrogels and their properties will be presented as well as the mechanisms of ionotropic gelation or chemical crosslinking. Methods of producing gellan hydrogels and their possible applications related to improved release, bioavailability, and therapeutic activity were described.

Preparation of Lambda-Cyhalothrin-Loaded Chitosan Nanoparticles and Their Bioactivity against Drosophila suzukii

The encapsulation of pesticides within nanoparticles is a promising approach of advanced technology in sustainable agriculture. Lambda-cyhalothrin (LC) was encapsulated by the ionotropic gelation technique into chitosan (CS)/tripolyphosphate (TPP) and CS/alginate (ALG) matrixes. CS-LC nanoparticles were characterized, and their efficacy was then evaluated against the key pest of soft fruits in Europe and the United States, Drosophila suzukii. The encapsulation efficiency (74%), nanoparticle yield (80%), polydispersity index (0.341), zeta potential (-23.1 mV) and particle size (278 nm) were determined at the optimum conditions. FTIR confirmed the cross-linkage between CS and TPP/ALG in the nanoparticles. The optimum formula recommended by the fractional factorial design was associated with the formulation variables of CS of high or low molecular weight, cross-linking agent (TPP), LC concentration (1.5% w/v) and stirring rate (1500 rpm), showing the highest desirability value (0.5511). CS-LC nanoparticles of the lowest particle size (278 nm) exhibited the highest percent mortality of D. suzukii males (86%) and females (84%), exceeding that caused by the commercial product (Karate-zeon^® 10% CS) at 2 HAT. This is the first work to use the ionic gelation technique to make LC nanoparticles, to the best of our knowledge. The encapsulation of chemical pesticides within biodegradable polymeric nanoparticles could be helpful for establishing a sustainable IPM strategy with benefits for human and environmental health and the lifetime of pesticides.

Modulation of Chitosan-TPP Nanoparticle Properties for Plasmid DNA Vaccines Delivery

Nucleic acid vaccines have become a revolutionary technology to give a fast, safe, cost-effective and efficient response against viral infections, such as SARS-CoV-2 or Human papillomavirus (HPV). However, to ensure their effectiveness, the development of adequate methods to protect, carry, and deliver nucleic acids is fundamental. In this work, nanoparticles (NPs) of chitosan (CS)-tripolyphosphate (TPP)-plasmid DNA (pDNA) were thoroughly modulated and characterized, by measuring the charge and size through dynamic light scattering (DLS) and morphology by scanning electron microscopy (SEM). Stability, cytotoxicity and cellular uptake of NPs were also evaluated. Finally, the effect of polyplexes on the expression of HPV E7 antigen in human fibroblast and RAW cells was investigated through polymerase chain reaction (PCR) and real-time PCR. The results showed NPs with a spherical/oval shape, narrow size distribution <180 nm and positive zeta potentials (>20 mV) and good stability after one month of storage at 4 °C in formulation buffer or when incubated in culture medium and trypsin. In vitro studies of NPs cytotoxicity revealed that the elimination of formulation buffers led to an improvement in the rate of cell viability. The E7 antigen transcription was also increased for NPs obtained with high pDNA concentration (60 μg/mL). The analyzed CS-TPP-pDNA polyplexes can offer a promising vehicle for nucleic acid vaccines, not only in the prevention or treatment of viral infections, but also to fight emergent and future pathogens.

Electrosprayed chitosan-coated alginate-pectin beads as potential system for colon-targeted delivery of ellagic acid

BACKGROUND

Ellagic acid (EA), a potent dietary antioxidant, has limited bioavailability owing to its rapid absorption in the stomach and small intestine, and EA is transformed to more bioavailable compounds - urolithins - in the colon. An encapsulation system that sustains the release of EA in the gastrointestinal system and delivers more EA into the colon could improve the oral bioavailability of EA. Electrosprayed EA-loaded alginate-pectin beads were produced and coated with low- (LC) and high-molecular-weight chitosan (HC). The EA release from uncoated and coated beads under simulated gastrointestinal conditions was evaluated. The samples were characterized by particle size, gel strength, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) analysis.

RESULTS

The encapsulation efficiency (EE%) of EA ranged from 49.53% to 69.85% for uncoated beads, which was elevated up to 86.50% by coating, and LC coating provided higher EE%. Pectin addition to alginate and chitosan coating reduced the gel strength and changed the size depending on the molecular weight of chitosan. SEM images of pectin-added beads showed fewer cracks but more wrinkles, and chitosan coating presented more aggregated surfaces. The ionic interaction of alginate-pectin-chitosan and the entrapment of EA were confirmed by FTIR. In the gastric medium, EA release was very low from uncoated beads (15.2-19.8%), and totally restricted by chitosan coating. In the intestinal stage, EA release from LC-coated alginate-pectin beads was only 18%, and it was between 55% and 65% for uncoated or HC-coated counterparts.

CONCLUSION

The LC-coated alginate-pectin beads could be further explored as a potential system for colon-targeted delivery of EA. © 2021 Society of Chemical Industry.

Rheological and textural analysis as tools for investigation of drug-polymer and polymer-polymer interactions on the example of low-acyl gellan gum and mesalazine

PURPOSE

In the performed study, the rheological and textural parameters of gellan-based hydrogels were investigated and their dependence on three factors was taken into consideration: (i) The presence of the model drug, (ii) The presence and type of the ionic crosslinking agent, and (iii) the composition of the polymer network. The objective was to compare two analytical methods, regarded as complementary, and define to what extent the obtained results correlate with each other.

METHODS

The hydrogels contained low-acyl gellan gum or its mixtures with hydroxyethyl cellulose or κ-carrageenan. CaCl₂ and MgCl₂ were used as gelling agents. Mesalazine was used as a model drug. The rheological analysis included oscillatory stress and frequency sweeping. The texture profile analysis was performed to calculate texture parameters.

RESULTS

Placebo gels without the addition of gelling agents had the weakest structure. The drug had the strongest ability to increase the stiffness of the polymer network. The weakest structure revealed the placebo samples without the addition of gelling agents. Texture analysis revealed no significant influence of the drug on the strength of the gels, while rheological measurements indicated clear differences.

CONCLUSIONS

It can be concluded that in the case of some parameters methods correlate, that is, the effect related to gelling ions. However, the rheological analysis seems to be more precise and sensitive to some changes in the mechanical properties of the gels.

Pickering emulsion-templated ionotropic gelation of tocotrienol microcapsules: effects of alginate and chitosan concentrations and gelation process parameters

BACKGROUND

Throughout the past decade, Pickering emulsion has been increasingly utilized for the encapsulation of bioactive compounds due to its high stability and biocompatibility. In the present work, palm tocotrienols were initially encapsulated in a calcium carbonate Pickering emulsion, which was then subjected to alginate gelation and subsequent chitosan coating. The effects of wall material (alginate and chitosan) concentrations, gelation pH and time, and chitosan coating time on the encapsulation efficiency of palm tocotrienols were explored.

RESULTS

Our findings revealed that uncoated alginate microcapsules ruptured upon drying and exhibited low encapsulation efficiency (13.81 ± 2.76%). However, the addition of chitosan successfully provided a more complex and rigid external wall structure to enhance the stability of the microcapsules. By prolonging the crosslinking time from 5 to 30 min and increasing the chitosan concentration from 0.1% to 0.5%, the oil encapsulation efficiency was increased by 28%. Under the right gelation pH (pH 4), the extension of gelation time from 1 to 12 h resulted in an increase in alginate-Ca²⁺ crosslinkings, thus strengthening the microcapsules.

CONCLUSION

With the optimum formulation and process parameters, a high encapsulation efficiency (81.49 ± 1.75%) with an elevated oil loading efficiency (63.58 ± 2.96%) were achieved. The final product is biocompatible and can potentially be used for the delivery of palm tocotrienols. © 2021 Society of Chemical Industry.

Tuning of Hydrogel Architectures by Ionotropic Gelation in Microfluidics: Beyond Batch Processing to Multimodal Diagnostics

Microfluidics is emerging as a promising tool to control physicochemical properties of nanoparticles and to accelerate clinical translation. Indeed, microfluidic-based techniques offer more advantages in nanomedicine over batch processes, allowing fine-tuning of process parameters. In particular, the use of microfluidics to produce nanoparticles has paved the way for the development of nano-scaled structures for improved detection and treatment of several diseases. Here, ionotropic gelation is implemented in a custom-designed microfluidic chip to produce different nanoarchitectures based on chitosan-hyaluronic acid polymers. The selected biomaterials provide biocompatibility, biodegradability and non-toxic properties to the formulation, making it promising for nanomedicine applications. Furthermore, results show that morphological structures can be tuned through microfluidics by controlling the flow rates. Aside from the nanostructures, the ability to encapsulate gadolinium contrast agent for magnetic resonance imaging and a dye for optical imaging is demonstrated. In conclusion, the polymer nanoparticles here designed revealed the dual capability of enhancing the relaxometric properties of gadolinium by attaining Hydrodenticity and serving as a promising nanocarrier for multimodal imaging applications.

Investigation on Potential of Chitosan Nanoparticles for Oral Bioavailability Enhancement of Risedronate Sodium

Risedronate sodium (RS) is used in osteoporosis for bone reabsorption. It is a BCS class III drug having poor oral bioavailability (<0.63%) due to low permeability. In the present study, RS-loaded chitosan nanoparticles were developed to increase oral bioavailability and evaluated for various parameters. The DSC study indicated compatibility of RS with excipients in their physical mixture. The nanoparticles were prepared by ionotropic gelation technique and lyophilized. The optimized batch (RS-CNs) was found to have particles of size 268.7 nm and zeta potential of 24.9 mV. The TEM image of RS-CNs revealed discrete spherical particles. Angle of repose of 27.02 indicates good flow property of nanoparticles. FT-IR spectra of RS-CNs showed characteristic peaks of RS indicating compatibility of RS with the excipients. The mucin binding efficiency of RS-CNs was obtained as 63.42%. The in vitro release study of RS indicated controlled delivery from RS-CNs over 22 h. The release mechanism was found to be diffusion- and erosion-controlled release. Ex vivo study using rat intestine revealed faster permeation of 32.78% in 6 h from RS-CNs compared to plain drug solution. In vivo pharmacokinetic study in rats showed increased C_max (1.8 fold) from RS-CNs compared to marketed formulation. The relative bioavailability of 193% from RS-CNs indicated significant enhancement in bioavailability upon nanoparticle formulation. The RS-CNs were found to be stable at room and refrigerated conditions. In conclusion, developed RS-loaded chitosan nanoparticles seem to be a promising approach to increase oral bioavailability and can avoid upper GI tract side effects.

Crosslinking Strategies for the Microfluidic Production of Microgels

This article provides a systematic review of the crosslinking strategies used to produce microgel particles in microfluidic chips. Various ionic crosslinking methods for the gelation of charged polymers are discussed, including external gelation via crosslinkers dissolved or dispersed in the oil phase; internal gelation methods using crosslinkers added to the dispersed phase in their non-active forms, such as chelating agents, photo-acid generators, sparingly soluble or slowly hydrolyzing compounds, and methods involving competitive ligand exchange; rapid mixing of polymer and crosslinking streams; and merging polymer and crosslinker droplets. Covalent crosslinking methods using enzymatic oxidation of modified biopolymers, photo-polymerization of crosslinkable monomers or polymers, and thiol-ene “click” reactions are also discussed, as well as methods based on the sol−gel transitions of stimuli responsive polymers triggered by pH or temperature change. In addition to homogeneous microgel particles, the production of structurally heterogeneous particles such as composite hydrogel particles entrapping droplet interface bilayers, core−shell particles, organoids, and Janus particles are also discussed. Microfluidics offers the ability to precisely tune the chemical composition, size, shape, surface morphology, and internal structure of microgels by bringing multiple fluid streams in contact in a highly controlled fashion using versatile channel geometries and flow configurations, and allowing for controlled crosslinking.

Leflunomide Sustained Skin Delivery Based on Sulfobetaine-Modified Chitosan Nanoparticles Embedded in Biodegradable Polyesters Films

The aim of the present study was to prepare a leflunomide (LFD) sustained release transdermal delivery system for the treatment of psoriasis. In this context, LFD-loaded nanoparticles (NPs) based on either neat chitosan (CS) or CS modified with [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SDAEM, a sulfobetaine zwitterionic compound) were initially prepared via ionotropic gelation and characterized in terms of in vitro dissolution, physicochemical, and antibacterial properties. Results showed that the use of the SDAEM-modified CS resulted in the formation of LFD-loaded NPs with improved wetting and solubilization properties, better in vitro dissolution profile characteristics (i.e., higher dissolution rate and extent), and improved (enhanced) antibacterial properties. The resultant LFD-loaded NPs were then embedded in suitable thin-film skin patches, prepared via spin-coating, utilizing two different biodegradable polyesters, namely methoxy polyethylene glycol-b-poly(L-lactide) (mPEG-b-PLA, at a ratio of 25/75 mPEG to PLA) and poly(lactic-co-glycolic acid) (PLGA at a ratio of 75/25 DL-lactide/glycolide copolymer). Results showed the formation of polymeric thin-films with no agglomeration (or trapped air) and uniform structure in all cases, while the LFD-loaded NPs were successfully embedded in the polymeric matrix. Analysis of the obtained in vitro dissolution profiles revealed a sustained release profile of the drug for up to approximately twelve days, while between the two proposed systems, the use of CS-SDAEM NPs (independently of the polyester type) was the most promising formulation approach.

Ionotropic Gelation of Chitosan Flat Structures and Potential Applications

The capability of some polymers, such as chitosan, to form low cost gels under mild conditions is of great application interest. Ionotropic gelation of chitosan has been used predominantly for the preparation of gel beads for biomedical application. Only in the last few years has the use of this method been extended to the fabrication of chitosan-based flat structures. Herein, after an initial analysis of the major applications of chitosan flat membranes and films and their usual methods of synthesis, the process of ionotropic gelation of chitosan and some recently proposed novel procedures for the synthesis of flat structures are presented.

Technologies and Formulation Design of Polysaccharide-Based Hydrogels for Drug Delivery

Polysaccharide-based hydrogel particles (PbHPs) are very promising carriers aiming to control and target the release of drugs with different physico-chemical properties. Such delivery systems can offer benefits through the proper encapsulation of many drugs (non-steroidal and steroidal anti-inflammatory drugs, antibiotics, etc) ensuring their proper release and targeting. This review discusses the different phases involved in the production of PbHPs in pharmaceutical technology, such as droplet formation (SOL phase), sol-gel transition of the droplets (GEL phase) and drying, as well as the different methods available for droplet production with a special focus on prilling technique. In addition, an overview of the various droplet gelation methods with particular emphasis on ionic cross-linking of several polysaccharides enabling the formation of particles with inner highly porous network or nanofibrillar structure is given. Moreover, a detailed survey of the different inner texture, in xerogels, cryogels or aerogels, each with specific arrangement and properties, which can be obtained with different drying methods, is presented. Various case studies are reported to highlight the most appropriate application of such systems in pharmaceutical field. We also describe the challenges to be faced for the breakthrough towards clinic studies and, finally, the market, focusing on the useful approach of safety-by-design (SbD).

Ionotropic Gelation of Chitosan for Next-Generation Composite Proton Conducting Flat Structures

(1) Background: Ionotropic gelation of cost-effective and eco-friendly biopolymer chitosan (Chit) is a novel and promising approach to the one-step synthesis of proton-conducting fuel cell bio-membranes.The method discovered by the author in 2011 and subsequently drowned among very few papers. This work aimed to relaunch this method through clear and effective communication of new unpublished results emphasizing the key aspects of this topic for successful dissemination of the results and significant future developments. (2) Methods and results: The mechanism of in-situ ionotropic gelation of Chit on an alumina substrate by phosphotungtate anions (PWA3-) was discussed and analyzed. The study sheds light on the effect of prolonged post-treatment in phosphotungstic acid (PWA) solution on the obtained chitosan/phosphotungstate (Chit-PWA) flat structures. Methods used included combined structural (XRD), thermal-gravimetric (DTG), electrochemical (in-situ EIS), compositional (EDX),morphological analysis (SEM), as well as the performances in a low temperature H2/O2 fuel cell(4) Conclusions: This contribution discloses novel possibilities aimed at increasing the impact of ionotropic gelation of chitosan on the scientific community working on the synthesis of novel proton conductive bio-composite membranes and structures.

Stable Chitosan-Based Nanoparticles Using Polyphosphoric Acid or Hexametaphosphate for Tandem Ionotropic/Covalent Crosslinking and Subsequent Investigation as Novel Vehicles for Drug Delivery

Chitosan nanoparticles (NPs) are widely studied as vehicles for drug, protein, and gene delivery. However, lack of sufficient stability, particularly under physiological conditions, render chitosan NPs of limited pharmaceutical utility. The aim of this study is to produce stable chitosan NPs suitable for drug delivery applications. Chitosan was first grafted to phthalic or phenylsuccinic acids. Subsequently, polyphosphoric acid (PPA), hexametaphosphate (HMP), or tripolyphosphate (TPP) were used to achieve tandem ionotropic/covalently crosslinked chitosan NPs in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC). Thermal and infrared traits confirmed phosphoramide bonds formation tying chitosan with the polyphosphate crosslinkers within NPs matrices. DLS and TEM size analysis indicated spherical NPs with size range of 120 to 350 nm. The generated NPs exhibited excellent stabilities under harsh pH, CaCl₂, and 10% FBS conditions. Interestingly, DLS, NPs stability and infrared data suggest HMP to reside within NPs cores, while TPP and PPA to act mainly as NPs surface crosslinkers. Drug loading and release studies using methylene blue (MB) and doxorubicin (DOX) drug models showed covalent PPA- and HMP-based NPs to have superior loading capacities compared to NPs based on unmodified chitosan, generated by ionotropic crosslinking only or covalently crosslinked by TPP. Doxorubicin-loaded NPs were of superior cytotoxic properties against MCF-7 cells compared to free doxorubicin. Specifically, DOX-loaded chitosan-phthalate polyphosphoric acid-crosslinked NPs exhibited 10-folds cytotoxicity enhancement compared to free DOX. The use of PPA and HMP to produce covalently-stabilized chitosan NPs is completely novel.

Enhanced Water Dispersibility of Curcumin Encapsulated in Alginate-Polysorbate 80 Nano Particles and Bioavailability in Healthy Human Volunteers

BACKGROUND

The turmeric (Curcuma longa) plant, a perennial herb of the ginger family, is an agronomic crop in the south and southeast tropical Asia. Turmeric an Indian yellow gold and universal spice is described in Ayurveda, an ancient treatise on longevity and quality life for the treatment of various inflammatory disorders. The oral bioavailability of curcumin is low due to poor aqueous solubility, alkaline instability and speedy elimination.

OBJECTIVE

The present study is designed to prepare alginate polysorbate 80 nanoparticles to enhance aqueous solubility/dispersibility, hence bioavailability.

METHOD

Curcumin-loaded alginate - polysorbate 80 nanoparticles were prepared by ionotropic gelation technique.

RESULTS

The optimized nano particles exhibited higher encapsulation efficiency (95%), particle size of 383 nm and Zeta potential of +200 mV. Formulations exhibited very low dissolution in Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF), but the major portion released in SCF which is attributed to the digestibility of alginate in Simulated Colonic Fluid (SCF) under the influence of colonic micro flora. FTIR and DSC observations revealed the successful entrapment of curcumin in alginate polysorbate-80 nanoparticles. The nanoparticles were more spherical, discrete and homogeneous. In healthy human volunteers, the oral bioavailability (AUC) of curcumin increased 5-fold after the consumption of curcumin nanosuspension compared to curcumin suspension. Maximum plasma concentration Cmax- 636 ± 122 ng/ml was observed at tmax- 2h for nanosuspension, whereas Cmax-87.7 ± 17.9ng/ml at tmax- 4h for suspension.

CONCLUSION

Curcumin-loaded alginate - polysorbate 80 nanoparticles prepared by ionotropic gelation method, successfully entrapped curcumin. Both curcumin suspension and curcumin nanosuspension were safe and well tolerated and may thus be useful in the prevention or treatment of various inflammatory diseases of mankind.

Gellan Gum/Laponite Beads for the Modified Release of Drugs: Experimental and Modeling Study of Gastrointestinal Release

In this study, gellan gum (GG), a natural polysaccharide, was used to fabricate spherical porous beads suitable as sustained drug delivery systems for oral administration. GG was cross-linked with calcium ions to prepare polymeric beads. Rheological studies and preliminary experiments of beads preparation allowed to identify the GG and the CaCl2 concentrations suitable for obtaining stable and spherical particles. GG beads were formed, through ionotropic gelation technique, with and without the presence of the synthetic clay laponite. The resultant beads were analyzed for dimensions (before and after freeze-drying), morphological aspects and ability to swell in different media miming biological fluids, namely SGF (Simulated Gastric Fluid, HCl 0.1 M) and SIF (Simulated Intestinal Fluid, phosphate buffer, 0.044 M, pH 7.4). The swelling degree was lower in SGF than in SIF and further reduced in the presence of laponite. The GG and GG-layered silicate composite beads were loaded with two model drugs having different molecular weight, namely theophylline and cyanocobalamin (vitamin B12) and subjected to in-vitro release studies in SGF and SIF. The presence of laponite in the bead formulation increased the drug entrapment efficiency and slowed-down the release kinetics of both drugs in the gastric environment. A moving-boundary swelling model with "diffuse" glassy-rubbery interface was proposed in order to describe the swelling behavior of porous freeze-dried beads. Consistently with the swelling model adopted, two moving-boundary drug release models were developed to interpret release data from highly porous beads of different drugs: drug molecules, e.g., theophylline, that exhibit a typical Fickian behavior of release curves and drugs, such as vitamin B12, whose release curves are affected by the physical/chemical interaction of the drug with the polymer/clay complex. Theoretical results support the experimental observations, thus confirming that laponite may be an effective additive for fabricating sustained drug delivery systems.

Local Structure of Ca2+ Alginate Hydrogels Gelled via Competitive Ligand Exchange and Measured by Small Angle X-Ray Scattering

Alginates, being linear anionic co-polymers of 1,4-linked residues β-d-ManA (M) and α-l-GulA (G), are widely applied as hydrogel biomaterials due to their favourable in vivo biocompatibility and convenient ionic crosslinking. The "egg-box" model is the prevailing description of the local structure of junction zones that form between the alginate chains and divalent cations, such as Ca2+, when ionic gelation occurs. In the present study we address to what extent signatures of lateral dimerization and further lateral association of junction zones also represent a valid model for the gelation of alginate using the recently reported method of competitive ligand exchange of chelated Ca2+ ions as a method for introducing gelling ions at constant pH. Small angle X-ray scattering with a q range from 0.1 to 3.3 nm-1 was employed to determine local structure in the hydrogel, using a custom-made fluid sample cell inserted in the X-ray beam. The scattering volume was intended to be localized to the contact zone between the two injected aqueous alginate solutions, and data was captured to resolve the kinetics of the structure formation at three different conditions of pH. The data show evolution of the local structure for the Ca2+ induced formation of junction zones in an alginate with 68% G residues, characterized by cross-sectional radii that could be accounted for by a two-component, broken rod like model. The evolution of the two component weight fractions apparently underpinned the connectivity, as reflected in the rheological data.

High Catalytic Activity of Lipase from Yarrowia lipolytica Immobilized by Microencapsulation

Microencapsulation of lipase from Yarrowia lipolytica IMUFRJ 50682 was performed by ionotropic gelation with sodium alginate. Sodium alginate, calcium chloride and chitosan concentrations as well as complexation time were evaluated through experimental designs to increase immobilization yield (IY) and immobilized lipase activity (ImLipA) using p-nitrophenyl laurate as substrate. To adjust both parameters (IY and ImLipA), the desirability function showed that microcapsule formation with 3.1%(w/v) sodium alginate, 0.19%(w/v) chitosan, 0.14 M calcium chloride, and 1 min complexation time are ideal for maximal immobilization yield and immobilized lipase activity. A nearly twofold enhancement in Immobilization yield and an increase up to 280 U/g of the lipase activity of the microcapsules were achieved using the experimental design optimization tool. Chitosan was vital for the high activity of this new biocatalyst, which could be reused a second time with about 50% of initial activity and for four more times with about 20% of activity.

Deep Insight into PEGylation of Bioadhesive Chitosan Nanoparticles: Sensitivity Study for the Key Parameters Through Artificial Neural Network Model

Ionically cross-linked chitosan nanoparticles have great potential in nanomedicine due to their tunable properties and cationic nature. However, low solubility of chitosan severely limits their potential clinical translation. PEGylation is a well-known method to increase solubility of chitosan and chitosan nanoparticles in neutral media; however, effect of PEG chain length and chitosan/PEG ratio on particle size and zeta potential of nanoparticles are not known. This study presents a systematic analysis of the effect of PEG chain length and chitosan/PEG ratio on size and zeta potential of nanoparticles. We prepared PEGylated chitosan chains prior to the nanoparticle synthesis with different PEG chain lengths and chitosan/PEG ratios. To precisely estimate the influence of critical parameters on size and zeta potential of nanoparticles, we both developed an artificial neural network (ANN) model and performed experimental characterization using the three independent input variables: (i) PEG chain length, (ii) chitosan/PEG ratio, and (iii) pH of solution. We studied the influence of PEG chain lengths of 2, 5, and 10 kDa and three different chitosan/PEG ratios (25 mg chitosan to 4, 12, and 20 μmoles of PEG) for the synthesis of chitosan nanoparticles within the pH range of 6.0-7.4. Artificial neural networks is a modeling tool used in nanomedicine to optimize and estimate inherent properties of the system. Inherent properties of a nanoparticle system such as size and zeta potential can be estimated based on previous experiment results, thus, nanoparticles with desired properties can be obtained using an ANN. With the ANN model, we were able to predict the size and zeta potential of nanoparticles under different experimental conditions and further confirmed the cell-nanoparticle adhesion behavior through experiments. Nanoparticle groups that had higher zeta potentials promoted adhesion of HEK293-T cells to nanoparticle-coated surfaces in cell culture medium, which was predicted through ANN model prior to experiments. Overall, this study comprehensively presents the PEGylation of chitosan, synthesis of PEGylated chitosan nanoparticles, utilizes ANN model as a tool to predict important properties such as size and zeta potential, and further captures the adhesion behavior of cells on surfaces prepared with these engineered nanoparticles.

Biocompatible Coatings from Smart Biopolymer Nanoparticles for Enzymatically Induced Drug Release

Nanoparticles can be used as a smart drug delivery system, when they release the drug only upon degradation by specific enzymes. A method to create such responsive materials is the formation of hydrogel nanoparticles, which have enzymatically degradable crosslinkers. Such hydrogel nanoparticles were prepared by ionotropic gelation sodium alginate with lysine-rich peptide sequences-either α-poly-L-lysine (PLL) or the aggrecanase-labile sequence KKKK-GRD-ARGSV↓NITEGE-DRG-KKKK. The nanoparticle suspensions obtained were analyzed by means of dynamic light scattering and nanoparticle tracking analysis. Degradation experiments carried out with the nanoparticles in suspension revealed enzyme-induced lability. Drugs present in the polymer solution during the ionotropic gelation can be encapsulated in the nanoparticles. Drug loading was investigated for interferon-β (IFN-β) as a model, using a bioluminescence assay with MX2Luc2 cells. The encapsulation efficiency for IFN-β was found to be approximately 25%. The nanoparticles suspension can be used to spray-coat titanium alloys (Ti-6Al-4V) as a common implant material. The coatings were proven by ellipsometry, reflection-absorption infrared spectroscopy, and X-ray photoelectron spectroscopy. An enzyme-responsive decrease in layer thickness is observed due to the degradation of the coatings. The Alg/peptide coatings were cytocompatible for human gingival fibroblasts (HGFIB), which was investigated by CellTiterBlue and lactate dehydrogenase (LDH) assay. However, HGFIBs showed poor adhesion and proliferation on the Alg/peptide coatings, but these could be improved by modification of the alginate with a RGD-peptide sequence. The smart drug release system presented can be further tailored to have the right release kinetics and cell adhesion properties.

Intranasal delivery of tapentadol hydrochloride-loaded chitosan nanoparticles: formulation, characterisation and its in vivo evaluation

The aim of the present investigation was to formulate tapentadol hydrochloride-loaded chitosan nanoparticles (CS-NPs) for nose to brain delivery. Chitosan nanoparticles were prepared using ionotropic gelation technique. Optimisation of the formulation and process parameters was done using Box-Behnken Design. The entrapment efficiency, drug loading, Z-average size and zeta potential of the optimised batch were 63.49 ± 1.61%, 17.25 ± 1.38%w/w, 201.2 ± 1.5 nm and +49.3 mV, respectively. In-vitro release study showed 84.04 ± 1.53% drug release after 28 h, while ex vivo studies indicated higher permeation of CS-NPs through nasal mucosa. The nanoparticles exhibited good mucoadhesiveness, haemocompatibility and safety as evidenced by histopathology. The results of the pharmacodynamic study revealed prolongation of the analgesic activity. The intranasal instillation of CS-NPs resulted in the higher concentrations in brain compared to the drug solution and intravenous administration of CS-NPs. In a nutshell, intranasal administration of tapentadol hydrochloride-loaded CS-NPs is a promising approach for effective pain management.

Optimization and Evaluation of Gastroretentive Ranitidine HCl Microspheres by Using Factorial Design with Improved Bioavailability and Mucosal Integrity in Ulcer Model

The purpose of our investigation was to develop and optimize the drug entrapment efficiency and bioadhesion properties of mucoadhesive chitosan microspheres containing ranitidine HCl prepared by an ionotropic gelation method as a gastroretentive delivery system; thus, we improved their protective and therapeutic gastric effects in an ulcer model. A 3 × 2² full factorial design was adopted to study the effect of three different factors, i.e., the type of polymer at three levels (chitosan, chitosan/hydroxypropylmethylcellulose, and chitosan/methylcellulose), the type of solvent at two levels (acetic acid and lactic acid), and the type of chitosan at two levels (low molecular weight (LMW) and high molecular weight (HMW)). The studied responses were particle size, swelling index, drug entrapment efficiency, bioadhesion (as determined by wash-off and rinsing tests), and T _80% of drug release. Studies of the in vivo mucoadhesion and in vivo protective and healing effects of the optimized formula against gastric ulcers were carried out using albino rats (with induced gastric ulceration) and were compared to the effects of free ranitidine powder. A pharmacokinetic study in rabbits showed a significant, 2.1-fold increase in theAUC_0-24of the ranitidine microspheres compared to free ranitidine after oral administration. The optimized formula showed higher drug entrapment efficiency and mucoadhesion properties and had more protective and healing effects on induced gastric ulcers in rats than ranitidine powder. In conclusion, the prolonged gastrointestinal residence time and the stability of the mucoadhesive microspheres of ranitidine as well as the synergistic healing effect of chitosan could contribute to increasing the potential of its anti-gastric ulcer activity.

Design and characteristics of gellan gum beads for modified release of meloxicam

The aim of the presented work was to design, formulate and evaluate the properties of low-acyl gellan macro beads with the potential application as carriers for oral delivery of meloxicam (MLX) in the prophylaxis of colorectal cancer. The beads were obtained by means of ionotropic gelation technique. Calcium chloride (1.0%, 9.0 × 10^-2 M) was used as the cross-linking agent. Nine different polymer, drug and surfactant (Tween^®80) mixtures were used for production of the beads. The quantitative compositions of the mixtures were generated with the application of the Design of Experiments (DoE) modulus from the STATISTICA Software. The prepared formulations revealed 7.2-27.0% of drug loading and 29.2-50.7% drug encapsulation efficiency. It turned out that 0.5% amount of gellan gum in the mixtures was not sufficient to obtain spherical beads. The morphology and surface of the dried beads were analyzed by SEM. Raman spectra confirmed that MLX did not undergo structural changes during production of the beads. The swelling behavior and degradation of the beads were evaluated in three simulated gastrointestinal fluids at different pH (1.2; 4.5; 6.8). The MLX in vitro release studies were conducted on USP apparatus IV, working in the open loop mode. The obtained results showed that MLX release from the dried beads was pH-dependent. The formulations obtained from mixtures containing 1.0 and 1.5% of gellan may be considered as oral dosage forms for MLX, intended to omit the stomach and release the drug in the distal parts of the gastrointestinal tract.

Carboxymethylinulin-Chitosan Nanoparticles for the Delivery of Antineoplastic Mitoxantrone

Mitoxantrone (MTX) is an antineoplastic agent whose use is limited by serious side effects on non-neoplastic cells. The aim of this study was the development of a new drug release system using an ionotropic gelation technique for microencapsulation of MTX in chitosan-carboxymethylinulin nanoparticles (CCInp), followed by evaluation of their cytotoxic effects on neoplastic MDA-MB-231 and non-neoplastic NIH3T3 cell lines. The CCInp were prepared through a new reliable method for easy functionalization of both inulin and chitosan. Both unloaded and drug-loaded nanoparticles were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS) and showed a spherical morphology with an average hydrodynamic diameter between 40 and 80 nm. Both nanoparticles were stable and easily degraded by lysozyme. MTX-loaded nanoparticles led to a greater mortality of MDA-MB-231 relative to free drug due to the ability of the nanoparticles to accumulate preferentially in neoplastic cells. The developed drug release system retains the ability to kill MDA-MB-231 cells in vitro, improving the survival of NIH3T3 cells.

Nozzleless Fabrication of Oil-Core Biopolymeric Microcapsules by the Interfacial Gelation of Pickering Emulsion Templates

Ionotropic gelation has been an attractive method for the fabrication of biopolymeric oil-core microcapsules due to its safe and mild processing conditions. However, the mandatory use of a nozzle system to form the microcapsules restricts the process scalability and the production of small microcapsules (<100 μm). We report, for the first time, a nozzleless and surfactant-free approach to fabricate oil-core biopolymeric microcapsules through ionotropic gelation at the interface of an O/W Pickering emulsion. This approach involves the self-assembly of calcium carbonate (CaCO3) nanoparticles at the interface of O/W emulsion droplets followed by the addition of a polyanionic biopolymer into the aqueous phase. Subsequently, CaCO3 nanoparticles are dissolved by pH reduction, thus liberating Ca(2+) ions to cross-link the surrounding polyanionic biopolymer to form a shell that encapsulates the oil droplet. We demonstrate the versatility of this method by fabricating microcapsules from different types of polyanionic biopolymers (i.e., alginate, pectin, and gellan gum) and water-immiscible liquid cores (i.e., palm olein, cyclohexane, dichloromethane, and toluene). In addition, small microcapsules with a mean size smaller than 100 μm can be produced by selecting the appropriate conventional emulsification methods available to prepare the Pickering emulsion. The simplicity and versatility of this method allows biopolymeric microcapsules to be fabricated with ease by ionotropic gelation for numerous applications.

External Cross-linked Mucoadhesive Microbeads for Prolonged Drug Release: Development and In vitro Characterization

Mucoadhesive microbeads of low methoxyl pectin were prepared, either alone or in combinations with hydroxypropyl methyl cellulose, sodium carboxymethyl cellulose, methyl cellulose and carbopol 934P, by ionotropic gelation. The influence of copolymers on mucoadhesivity, microbeads characteristics and in vitro drug release was investigated. Spherical microbeads with 78.69±0.59 to 85.84±0.78% drug entrapment and of a size of 791.90±4.58 to 960.88±4.61 μm were prepared. The concentration of cross linking agent affects the encapsulation efficiency of microbeads. Mucoadhesiveness of microbeads was dependent on the concentration of copolymers. The formulations exhibiteda pH-dependent release and followed diffusion-controlled first-order kinetics.

Advances in preparation and characterization of chitosan nanoparticles for therapeutics

CONTEXT

Polymers have been largely explored for the preparation of nanoparticles due to ease of preparation and modification, large gene/drug loading capacity, and biocompatibility. Various methods have been adapted for the preparation and characterization of chitosan nanoparticles.

OBJECTIVE

Focus on the different methods of preparation and characterization of chitosan nanoparticles.

METHODS

Detailed literature survey has been done for the studies reporting various methods of preparation and characterization of chitosan nanoparticles.

RESULTS AND CONCLUSION

Published database suggests of several methods which have been developed for the preparation and characterization of chitosan nanoparticles as per the application.

Characterization of protein and peptide binding to nanogels formed by differently charged chitosan derivatives

Chitosan (Chi) is a natural biodegradable cationic polymer with remarkable potency as a vehicle for drug or vaccine delivery. Chi possesses multiple groups, which can be used both for Chi derivatization and for particle formation. The aim of this work was to produce stable nanosized range Chi gels (nanogels, NGs) with different charge and to study the driving forces of complex formation between Chi NGs and proteins or peptides. Positively charged NGs of 150 nm in diameter were prepared from hexanoyl chitosan (HC) by the ionotropic gelation method while negatively charged NGs of 190 nm were obtained from succinoyl Chi (SC) by a Ca²⁺ coacervation approach. NGs were loaded with a panel of proteins or peptides with different weights and charges. We show that NGs preferentially formed complexes with oppositely charged molecules, especially peptides, as was demonstrated by gel-electrophoresis, confocal microscopy and HPLC. Complex formation was accompanied by a change in zeta-potential and decrease in size. We concluded that complex formation between Chi NGs and peptide/proteins is mediated mostly by electrostatic interactions.

Chitosan microspheres in novel drug delivery systems

The main aim in the drug therapy of any disease is to attain the desired therapeutic concentration of the drug in plasma or at the site of action and maintain it for the entire duration of treatment. A drug on being used in conventional dosage forms leads to unavoidable fluctuations in the drug concentration leading to under medication or overmedication and increased frequency of dose administration as well as poor patient compliance. To minimize drug degradation and loss, to prevent harmful side effects and to increase drug bioavailability various drug delivery and drug targeting systems are currently under development. Handling the treatment of severe disease conditions has necessitated the development of innovative ideas to modify drug delivery techniques. Drug targeting means delivery of the drug-loaded system to the site of interest. Drug carrier systems include polymers, micelles, microcapsules, liposomes and lipoproteins to name some. Different polymer carriers exert different effects on drug delivery. Synthetic polymers are usually non-biocompatible, non-biodegradable and expensive. Natural polymers such as chitin and chitosan are devoid of such problems. Chitosan comes from the deacetylation of chitin, a natural biopolymer originating from crustacean shells. Chitosan is a biocompatible, biodegradable, and nontoxic natural polymer with excellent film-forming ability. Being of cationic character, chitosan is able to react with polyanions giving rise to polyelectrolyte complexes. Hence chitosan has become a promising natural polymer for the preparation of microspheres/nanospheres and microcapsules. The techniques employed to microencapsulate with chitosan include ionotropic gelation, spray drying, emulsion phase separation, simple and complex coacervation. This review focuses on the preparation, characterization of chitosan microspheres and their role in novel drug delivery systems.

Ionotropically Gelled Novel Hydrogel Beads: Preparation, Characterization and In vitro Evaluation

Prolonged release drug delivery system of stavudine was made by ionotropic gelation and polyelectrolyte complexation technique. Cross-linking reinforced chitosan-gellan complex beads were prepared by gelation of anionic gellan gum, the primary polymer, with oppositely charged counter ion to form beads which were further complexed with chitosan as a polyelectrolyte. The effect of this polymer on release profile of drug was studied. Beads without chitosan complexation were also made. The reaction of chitosan-gellan complex dominates the formation of skin layer on the surface of beads. Stavudine an antiretroviral drug was selected as novel drug for the experiment. The final formulations were subjected to in vitro evaluation and several characterization studies. Batches with gellan gum shows Higuchi model, while chitosan-gellan shows zero order release. All the batches with copolymer showed sustained the drug release more than 12 h, whereas with gellan gum alone showed up to 10 h. Batches with chitosan showed maximum drug encapsulation efficiency.