Remote controlled drug release from multi-functional Fe3O4/GO/Chitosan microspheres fabricated by an electrospray method

The construction of multifunctional microspheres for remote controlled drug release requires the exquisite selection of composite materials and preparation approaches. In this study, chitosan, an amino polysaccharide, was blended with inorganic nanocomponents, Fe₃O₄ and graphene oxide (GO) and electrosprayed to fabricate uniform microspheres with the diameters ranging from 100μm to 1100μm. An anti-cancer drug, doxorubicin (DOX), was loaded to the microspheres by an adsorption or embedding method. The microsphere is responsive to magnetic fields due to the presence of Fe₃O₄, and the incorporation of GO enhanced the drug loading capacity. The fast stimuli-responsive release of DOX can be facilely controlled by using NIR irradiation due to the strong photo-thermal conversion of Fe₃O₄ and GO_. In addition, ultrasound was used as another external stimulus for DOX release. The results suggest the Fe₃O₄/GO/Chitosan microspheres fabricated by the electrospray method provide an efficient platform for remote controlled drug release, which may have potential applications in drug eluting microspheres.

Magnetic chitosan microspheres: An efficient and recyclable adsorbent for the removal of iodide from simulated nuclear wastewater

The efficient and recyclable magnetic chitosan microspheres (MCMs) were successfully synthesized to remove iodide from nuclear wastewater and characterized through XRD, FTIR, SEM, EDS, VSM, TGA and XPS. The characterization results indicated that the MCMs exhibited smooth spherical morphology and good magnetic properties. The removal potential of MCMs was investigated for iodide (I^-) anions at different conditions. From pH 3 to pH 9, MCMs performed the high I^- removal efficiency (>90%). The maximum I^- removal capacity of MCMs was up to 0.8087 mmol g^-1 at 298 K, well-fitting with the pseudo-second-order and Sips models. Furthermore, the I^- removal efficiency of MCMs still maintained more than 91% after five adsorption-desorption cycles, performing good regeneration and reusability. This study is expected to prompt the MCMs to become an efficient and recyclable biosorbent for iodide removal from nuclear wastewater.

Enhancement of laccase immobilization onto wet chitosan microspheres using an iterative protocol and its potential to remove micropollutants

This study was focused on creating a new and effective immobilization method for Trametes versicolor laccase (Lc) by using chitosan (CS) microspheres activated with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride. The activation of the support alternated with immobilization of the enzyme, in repetitive procedures, led to obtaining three different products. Also, the physicochemical properties of the new products were investigated and compared with those of free laccase. The discoloration and reusability properties of the immobilized Lc were evaluated using indigo carmine (IC) as a model micropollutant. The ESEM and FT-IR methods demonstrated that the Lc was successfully immobilized. The relative reaction rate and the total amount of immobilized Lc were tripled using the iterative protocol as proved by specific and Bradford assays. The maximum amount of immobilized Lc was 8.4 mg Lc/g CS corresponding to the third immobilization procedure. Compared to the free Lc, the operational stability of the immobilized Lc was significantly improved, presenting a maximum activity plateau over a pH range of 3-5 and a temperature range of 25-50 °C. The thermal inactivation study at 55 °C proved that the immobilized enzyme is three times more stable than the free Lc. The isoconversional and Michaelis-Menten methods showed that the immobilization did not affect the enzyme catalytic properties. After 32 days of storage, the residual activities are 85% for the immobilized laccase and 40% for the free one. In similar conditions, the free and immobilized Lc (2.12 x 10^-6 M) completely decolorized IC (7.15 x 10^-5 M) within 14 min. The immobilized Lc activity remained almost constant (80%) during 10 reusability cycles. All these results highlight the substantial advantages of the new immobilization protocol and demonstrate that immobilized Lc can be used as a promising micropollutant removal from real wastewater.

Ferrocene crosslinked and functionalized chitosan microspheres towards bio-based Fenton-like system for the removal of organic pollutants

Dye-containing wastewater treatment has been a major long-term global challenge. For this purpose, a novel bio-based microspheres (CS-FC) with high specific surface area (63.24 m2·g-1) and nano-channels (17.95 nm) was prepared using chitosan as the framework and ferrocene as a crosslinking active group. CS-FC not only has the ability to rapidly enrich methyl orange (MO) through hydrogen-bonding and electrostatic attraction, but also almost completely degrades it in the presence of H2O2/K2S2O8 through a synergistic radical/non-radical mechanism under the activating effect of ferrocene. Without H2O2/K2S2O8, the maximum MO adsorption capacity of CS-FC is in the range 871-1050 mg·g-1, and conforms to a Langmuir isothermal model with pseudo-second-order kinetics. In the presence of H2O2/K2S2O8, the removal of MO dramatically increased from 32 % to nearly 100 % after incubation for 60 min, due to the simultaneous formation of highly reactive 1O2 and ·OH. The significant contribution from 1O2 endowed CS-FC/H2O2/K2S2O8 with high universality for degrading various organic pollutants (including azo dyes and antibiotics), a wide pH window (2-8), and low sensitivity to co-existing ions. Such cost-effective, recyclable porous bio-based microspheres are suitable for heterogeneous Fenton-like catalysis in organic wastewater treatment that rely on synergistic radical/non-radical reaction pathways.

Chitosan/β-glycerophosphate porous microsphere prepared by facile water-in-water emulsion as a topical hemostatic material

Acute hemorrhage is a major cause of death in many emergency cases. Although many hemostatic materials have been studied in recent years, it is still necessary to develop new hemostatic materials with remarkable efficiency, biosafety, convenient preparation, low cost, and good biodegradability. In this work, novel chitosan (CS)/β-glycerophosphate (β-GP) composite porous microsphere with a uniform size of 210.00 ± 2.14 μm was fabricated through water-in-water (W/W) emulsion via microencapsulation, which can avoid the use of toxic crosslink chemicals and organic solvents to achieve facile and efficient preparation of microspheres. β-GP could promote the formation of microspheres by enhancing the hydrogen-bonding interaction between CS chains, which contributed to the macro-porous structure. Owing to their large pore size (6.0 μm) and high specific surface area (37.8 m2/g), the CS/β-GP microspheres could absorb water quickly and adsorb protein, red blood cells, and platelets through electrostatic forces to promote blood coagulation. Furthermore, the CS/β-GP microspheres achieved a significantly shortened hemostatic time (45 s) and reduced blood loss (0.03 g) in a rat liver injury model. Rat tail amputation test also showed a satisfactory hemostatic effect. Overall, the green and porous CS/β-GP microspheres can be used as a facile and topical rapid hemostatic material.

Formulated chitosan microspheres remodelled the altered gut microbiota and liver miRNA in diet-induced Type-2 diabetic rats

Chitosan was formulated into a microsphere and comprehensively characterized and evaluated for its anti-inflammatory potential and anti-diabetic properties against the high sugar fat diet-induced diabetic animals. The diabetic model was induced through feeding with a high-sugar fat diet. Metformin, a standard antidiabetic drug, and CMS (chitosan microspheres) were administered orally for 90 days as reversal strategies. Upon completion of the study, the following parameters, such as serum biochemistry, cytokine analysis, tissue histology, liver miRNA sequencing, and Shotgun metagenomics studies from stool samples, were performed. SEM images of the microsphere indicated a smooth morphology, while FTIR and DSC respectively, confirmed the presence of functional groups of chitosan and the thermal stability of the formulation. Following HSFD induction, all the parameters analyzed were altered compared to the control group. In both reversal groups, serum biochemical parameters were restored, which was at par with the control. A significant increase in the anti-inflammatory cytokine IL-10, and a remarkable reduction in TNF-α and MCP-1 inflammatory cytokines were observed in both reversal groups. Tissue histology indicated improvements in low-grade inflammation, induced in the diabetic group. miR-203 was upregulated in the CMS-treated group, while miR-103 was downregulated. The study further delved into the impact on gut microbiota and KEGG. Major phyla i.e., Bacteroidetes, Cyanobacteria, Firmicutes, Proteobacteria, and Verrucomicrobia showed restoration, while upregulation of DNA polymerase zeta in T2D showed reversal after the treatment. The formulation showed reversal at par with metformin and also confirms its anti-diabetic and anti-inflammatory activities of CMS, with microfloral and miR regulatory functions.

Harnessing three-dimensional porous chitosan microsphere embedded with adipose-derived stem cells to promote nerve regeneration

BACKGROUND

Nerve guide conduits are a promising strategy for reconstructing peripheral nerve defects. Improving the survival rate of seed cells in nerve conduits is still a challenge and microcarriers are an excellent three-dimensional (3D) culture scaffold. Here, we investigate the effect of the 3D culture of microcarriers on the biological characteristics of adipose mesenchymal stem cells (ADSCs) and to evaluate the efficacy of chitosan nerve conduits filled with microcarriers loaded with ADSCs in repairing nerve defects.

METHODS

In vitro, we prepared porous chitosan microspheres by a modified emulsion cross-linking method for loading ADSCs and evaluated the growth status and function of ADSCs. In vivo, ADSCs-loaded microcarriers were injected into chitosan nerve conduits to repair a 12 mm sciatic nerve defect in rats.

RESULTS

Compared to the conventional two-dimensional (2D) culture, the prepared microcarriers were more conducive to the proliferation, migration, and secretion of trophic factors of ADSCs. In addition, gait analysis, neuro-electrophysiology, and histological evaluation of nerves and muscles showed that the ADSC microcarrier-loaded nerve conduits were more effective in improving nerve regeneration.

CONCLUSIONS

The ADSCs-loaded chitosan porous microcarrier prepared in this study has a high cell engraftment rate and good potential for peripheral nerve repair.