Fabrication of folic acid functionalized pH-responsive and thermosensitive magnetic chitosan microcapsules via a simple sonochemical method

Folate decorated chitosan-chondroitin sulfate nanoparticles loaded hydrogel for targeting macrophages against rheumatoid arthritis

Inflammatory cell infiltration, particularly macrophages, plays a major contribution to the pathogenesis of Rheumatoid Arthritis (RA). Exploiting the overexpression of folate receptors (FR-β) on these recruited macrophages has gained significant attraction for ligand-targeted delivery. Leflunomide (LEF), being an immunomodulatory agent is considered the cornerstone of the therapy, however, its oral efficacy is impeded by low solubility and escalating adverse effects profile. Therefore, in the present work, we developed Folate-conjugated chitosan-chondroitin sulfate nanoparticles encapsulating LEF for selective targeting at inflammatory sites in RA. For this purpose, the folate group was first conjugated with the chitosan polymer. After which, Folate Leflunomide Nanoparticles (FA-LEF-NPs) were synthesized through the ionotropic gelation method by employing FA-CHI and CHS. The polymers CHI and CHS were also presented with innate anti-inflammatory and anti-rheumatic attributes that were helpful in provision of synergistic effects to the formulation. These nanoparticles were further fabricated into a hydrogel, employing almond oil (A.O) as a permeation enhancer. The in vivo studies justified the preferential accumulation of FA-conjugated nanoparticles at inflamed joints more than any other organ in comparison to the free LEF and LEF-NPs formulation. The FA-LEF-NPs loaded hydrogel also ascertained a minimal adverse effect profile with an improvement of inflammatory cytokines expression.

A comparative study of starch-g-(glycidyl methacrylate)/synthetic polymer-based hydrogels

Chemical modification reactions and blending formation are two alternatives used to improve the properties of starch-based materials. This work used both approaches to evaluate how they would affect the properties of hydrogels. The hydrogels were based on corn starch (St), modified with glycidyl methacrylate (GMA; starch-g-GMA; ^GMASt), and blended with N,N'-dimethylacrylamide (DMAAm; ^GMASt_xDMAAm_y) or sodium acrylate (SA; ^GMASt_xSA_y). The results confirmed that the pure ^GMASt matrix had a low swelling degree (≈3 g g^-1), but when blended with the synthetic polymers, this value reached ≈10 g g^-1 (sample ^GMASt₂₅DMAAm₇₅). All matrices showed responsiveness towards pH variations. In general, they swelled more at pH 5 than at pH 7. While DMAAm had more influence on the swelling degree, SA was more efficient as a mechanical enhancer. Increasing 25 % of the amount of SA in the blend increased Young's Modulus by a factor of ≈10 times. It confirmed that both polymers effectively change the properties of ^GMASt, but in different ways.

Stimulus-responsive starch-based nanocapsules for targeted delivery and antimicrobial applications

Polysaccharide materials have attracted a widespread interest in the biomedical materials field due to their non-toxic, biocompatible and biodegradable properties. In this research, starch was modified with chloroacetic acid, folic acid (FA) and thioglycolic acid and then starch-based nanocapsules loaded with curcumin (FA-RSNCs@CUR) were prepared by the convenient oxidation method. The nanocapsules were prepared with stable particle size distribution of 100 nm. In the drug release test simulating the tumor microenvironment in vitro, the cumulative CUR release rate at 12 h was 85.18 %. Due to FA and FA receptor mediation, it only took 4 h for FA-RSNCs@CUR to achieve internalization by HeLa cells. In addition, cytotoxicity confirmed that starch-based nanocapsules have good biocompatibility as well as protection of normal cells in vitro. And FA-RSNCs@CUR showed certain antibacterial properties in vitro. Therefore, FA-RSNCs@CUR has good potential for future applications in food preservation and wound dressing, and so on.

Update of ultrasound-assembling fabrication and biomedical applications for heterogeneous polymer composites

As a power-driving approach, ultrasound irradiation is very appealing to the preparation or modification of new materials. In the review, we overviewed the latest development of ultrasound-mediated effects or reactions in polymer composites, and demonstrated its unique and powerful aspects on the polymerization or aggregation. The review generalized the different categories of heterogeneous polymer composites by defining the constituents, and described the shapes, sizes and basic properties of various purpose-specific or site-specific products. Importantly, the review paid more attention to the main biomedicine applications of heterogeneous polymer composites, such as drug or bioactive substance entrapment, delivery, release, imaging, and therapy, and emphasized many advantages of ultrasound-assembling approaches and heterogeneous polymer composites in biology and medicine fields. In addition, the review also indicated the prospective challenges of heterogeneous polymer composites both in ultrasound-assembling designs and in biomedical applications.

Optimum parameters for humic acid removal and power production by Al-air fuel cell electrocoagulation in synthetic wastewater

Although humic acid (HA) is a complex natural organic matter, it can potentially harm the environment and human health. In this study, aluminum-air fuel cell electrocoagulation (AAFCEC) was used to remove HAs from water while generating electricity. Initial pH, electrolyte concentration, HA concentration electrode distance and external resistance were investigated to determine the power generation and removal efficiency. The results showed that the better performance of power generation has been acquired in the alkaline solution and larger electrolyte concentration and short electrode distance. Further, Al-Ferron complexation timed spectrophotometry was used to determine the Al speciation distribution in the solution under different parameters. The power density of the cell reached 313.47 mW/cm² for the following conditions: 1 g/L NaCl concentration, 3 cm electrode distance, 20 Ω external resistor, and pH 9. After about an hour of electrolysis, the optimum removal rate of HA was above 99%. The results demonstrated that the AAFCEC is an efficient and eco-friendly water treatment process, and it could be further developed and disseminated in the rural areas and households.

Formulation of a pH-sensitive cancer cell-targeted gene delivery system based on folate-chitosan conjugated nanoparticles

In this study, we investigated the design and construct of a chitosan (CA)-based targeted gene delivery system and evaluated its function. To this end, CA-folic acid/pDNA (CA-FA/pDNA) nanoparticles were prepared in different formulations using the ion gelation method. All the synthesized nanoparticles were characterized using FTIR, TEM, SEM and DLS. Moreover, the effects of molecular weight (MW) of CA, DNA, and CA concentration were inspected on encapsulation efficiency (EE). The results showed that the EE of pDNA was directly proportional with MW of CA and CA concentration but was in an inverse proportion with DNA concentration. In addition, high MW of CA and low MW of CA nanoparticles showed lower and higher pDNA release in all pH ranges, respectively. It is concluded that the N/P ratio increase can cause controlled pDNA release.

Sonochemical fabrication of reduction-responsive magnetic starch-based microcapsules

In this work, a novel, biocompatible, non-immunogenic and reductive-responsive magnetic starch-based microcapsules (RMSMCs) were designed and fabricated successfully via a facile sonochemical method for targeted delivery and triggered release of hydrophobic drugs. TEM image indicated that oleic acid (OA) modified Fe₃O₄ nanoparticles (OA-Fe₃O₄ NPs) were encapsulated into RMSMCs. The obtained RMSMCs were endowed with magnetism for drug targeted delivery because that the superparamagnetic OA-Fe₃O₄ NPs were encapsulated into RMSMCs. Moreover, Coumarin 6 (C6), a green fluorescent dye, was used as a model hydrophobic drug and loaded into RMSMCs. As drug carriers, the obtained spherical RMSMCs with the average size of 2 μm presented excellent reductive-responsive release ability for hydrophobic drugs. Accordingly, the obtained RMSMCs would be promising carriers for targeted delivery and triggered release of hydrophobic drugs in biomedical applications.

Sonochemistry-Assembled Stimuli-Responsive Polymer Microcapsules for Drug Delivery

Stimuli-responsive polymer microcapsules (PMs) fabricated by the sonochemical method have emerged for developing useful drug delivery systems, and the latest developments are mainly focusing on the synthetic strategies and properties such as structure, size, stability, loading capacity, drug delivery, and release. There, the primary attribution of sonochemistry is to offer a simple and practical approach for the preparation of PMs. Structure, size, stability, and properties of PMs are designed mainly according to synthetic materials, implementation schemes, or specific demands. Numerous functionalities of PMs based on different stimuli are demonstrated: targeting motion in a magnetic field or adhering to the living cells with sensitive sites through molecular recognition, and stimuli-triggered release including enzymatic catalysis, chemical reaction as well as physical or mechanical process. The current review discusses the basic principles and mechanisms of stimuli effects, and describes the progress in the application such as targeted drug systems and controlled drug systems, and also gives an outlook on the future challenges and opportunities for drug delivery and theranostics.

Chitosan temperature-sensitive gel loaded with drug microspheres has excellent effectiveness, biocompatibility and safety as an ophthalmic drug delivery system

In the present study, a temperature-sensitive gel composed of chitosan, carboxymethyl chitosan and glycerophosphate was prepared and loaded with chitosan microspheres encapsulating levofloxacin. The bioavailability of levofloxacin and the safety of this novel opthalmic drug delivery formulation were evaluated. Levofloxacin chitosan microspheres were prepared using the ionic gelation method, and the particle size and entrapment rate were determined. The morphology of the microspheres was observed by scanning electron microscopy. The pH and zeta potential were measured. The in vitro release of levofloxacin by the chitosan temperature-sensitive gel loaded with drug microspheres was determined using spectrophotometry. The eye retention time of the chitosan temperature-sensitive gel was calculated using a fluorescein sodium test. To assess the bioavailability and safety of the chitosan temperature-sensitive gel, a cell compatibility test, a cytotoxicity test and skin irritation test were performed. The entrapment rate of levofloxacin in the chitosan microspheres was determined to be 26.5%. The levofloxacin chitosan microspheres that were formed by chitosan and sodium tripolyphosphate were identified to be suitable for use in an ophthalmic particle dispersion system based on their physical and chemical properties. The pH of the levofloxacin chitosan microsphere suspension was 5.87±0.04, the average particle diameter was 2,452±342 nm, the polydispersity index was 0.168±0.028 and the ζ potential was 28.62±1.7 mV. The chitosan temperature-sensitive gel carrying microspheres loaded with drug prevented drug burst release at the initial stage and facilitated the slow release of the drug later on. Furthermore, this delivery system markedly prolonged the contact duration of levofloxacin with the eye. The chitosan temperature-sensitive hydrogel was safe and provided a good bioavailability of the drug. The results revealed that the chitosan temperature-sensitive gel had a cytotoxicity of grade 0, and no erythematous response was observed during the entire course of the skin irritation test. The present study provided a basis for the future development of the chitosan-based temperature-sensitive hydrogel in ophthalmic drug delivery.

Fabrication of redox and pH dual-responsive magnetic graphene oxide microcapsules via sonochemical method

In this study, the biocompatible redox and pH dual-responsive magnetic graphene oxide microcapsules (MGOMCs) were prepared by a simple sonochemical method. The disulfide bonds cross-linked the wall of MGOMCs were formed from the hydrosulfuryl on the surface of thiolated graphene oxide, which was synthesized by functionalizing graphene oxide with cysteine, showed an excellent redox-responsive property to control drugs release. Moreover, oleic acid modified Fe₃O₄ nanoparticles were encapsulated into the microcapsules successfully with the hydrophobic drugs dispersed in the hydroxy silicone oil. The MGOMCs possess distinguished magnetic property and pH-responsive ability. Besides, the microcapsules could be engulfed by Hela cells successfully due to the appropriate size and flexible shell. The MGOMCs could be a good carrier for hydrophobic drugs, especially the anticancer drugs.

Probing the application of a zirconium coagulant in a coagulation–ultrafiltration process: observations on organics removal and membrane fouling

The Zr coagulant offered improved turbidity and organics removal and was beneficial in alleviating membrane fouling, particularly the irreversible fouling.

Ultrasonic synthesis of stable oil filled microcapsules using thiolated chitosan and their characterization by AFM and numerical simulations

An experimental protocol has been developed for synthesizing stable core-shell microcapsules using a biopolymer, chitosan, lacking cross-linkable thiol functional groups. In the first step, thiol moieties were introduced into the backbone of chitosan using dl-N-acetylhomocysteine thiolactone (AHT). In the second step, AHT-modified chitosan shelled microcapsules, encapsulating an oil core, were successfully prepared using high intensity 20 kHz ultrasound. The size of chitosan and AHT modified chitosan microcapsules was found to be in the range of 1-15 μm. The thickness of the microcapsule shell increased with an increase in thiol content. The mechanical properties of microcapsules were evaluated by subjecting the microcapsules to compressive forces by colloidal probe AFM. The stiffness and the Young's modulus of the shell of microcapsules were determined by analyzing the force versus indentation data using Reissner's theory for indentation of thin elastic shells. The stiffness of AHT modified chitosan microcapsules was found to be higher than unmodified chitosan microcapsules. The viability of microcapsules to be embedded into processed food, pharmaceutical and cosmetic products was tested via numerical simulations. The confined capsule in the micro-channel was subjected to linear shear and uniform flows. We used finite element numerical simulations to determine the deformation of microcapsules in flow as a function of shear rate and thickness of the shell. The deformation of capsule was found to be linear with an increase in the shear rate. The deformation decreased with an increase in the thickness of the shell. Based on the simulations, we predict that the microcapsules would survive processing conditions and shear rates used in industrial applications.