Temperature effect on the complex formation between Pluronic F127 and starch

Ecofriendly polysaccharide-based alginate/pluronic F127 semi-IPN hydrogel with magnetic collectability for precise release of pesticides and sustained pest control

Controlled-release systems are crucial for efficient pesticide utilization and environmental protection in agricultural production. The utilization of polysaccharide-based materials derived from biopolymers as carriers for controlling pesticide release holds significant potential. In this work, a reversible near infrared-responsive polysaccharide-based hydrogel (RNPH) was fabricated by employing a semi-interpenetrating polymer network (alginate-FeIII/pluronic F127) as a carrier to encapsulate Fe3O4@polydopamine (FP) and emamectin benzoate (EB)-loaded hollow mesoporous silica. The incorporation of FP into the RNPH introduced a photothermal effect, enabling the precise release of EB through reversible shrinkage of the hydrogel upon NIR irradiation. Additionally, the presence of magnetic Fe3O4 in the system facilitated the rapid removal of remaining RNPH from the environment using a magnet, reducing EB residue. Importantly, RNPH exhibited exceptional controlled-release performance and could be reused for at least 4 cycles. Furthermore, the anti-photolysis ability of EB protected by RNPH was enhanced by 4.8 times compared to EB alone. Moreover, RNPH significantly improved the adhesion of EB to foliar surfaces, thereby reducing the loss of EB while ensuring crop safety. Therefore, the polysaccharide-based hydrogel holds promise as a versatile carrier for the precise release of EB, offering valuable applications in enhancing pesticide bioavailability and promoting environmental safety.

Dual-action of thermoresponsive gels containing DsiRNA-loaded gold nanoparticles for diabetic wound therapy: Characterization, in vitro safety and healing efficacy

Diabetic wounds are difficult to treat due to multiple causes, including reduced blood flow and bacterial infections. Reduced blood flow is associated with overexpression of prostaglandin transporter (PGT) gene, induced by hyperglycaemia which causing poor vascularization and healing of the wound. Recently, gold nanoparticles (AuNPs) have been biosynthesized using cold and hot sclerotium of Lignosus rhinocerotis extracts (CLRE and HLRE, respectively) and capped with chitosan (CS) to produce biocompatible antibacterial nanocomposites. The AuNPs have shown to produce biostatic effects against selected gram positive and negative bacteria. Therefore, in this study, a dual therapy for diabetic wound consisting Dicer subtract small interfering RNA (DsiRNA) and AuNPs was developed to improve vascularization by inhibiting PGT gene expression and preventing bacterial infection, respectively. The nanocomposites were incorporated into thermoresponsive gel, made of pluronic and polyethylene glycol. The particle size of AuNPs synthesized using CLRE (AuNPs-CLRE) and HLRE (AuNPs-HLRE) was 202 ± 49 and 190 ± 31 nm, respectively with positive surface charge (+30 to + 45 mV). The thermoresponsive gels containing DsiRNA-AuNPs gelled at 32 ± 1 °C and released the active agents in sufficient amount with good texture and rheological profiles for topical application. DsiRNA-AuNPs and those incorporated into thermoresponsive pluronic gels demonstrated high cell viability, proliferation and cell migration rate via in vitro cultured cells of human dermal fibroblasts, indicating their non-cytotoxicity and wound healing properties. Taken together, the thermoresponsive gels are expected to be useful as a potential dressing that promotes healing of diabetic wounds.

Surfactant Structure-Dependent Interactions with Modified Starch Nanoparticles Probed by Fluorescence Spectroscopy

The interactions between the surfactants sodium dodecyl sulfate (SDS) and sodium dioctyl sulfosuccinate (AOT) and starch nanoparticles (SNPs) hydrophobically modified with the hydrophobic dye pyrene (Py-SNPs) were investigated in water by steady-state and time-resolved fluorescence. The Py-SNPs formed interparticulate aggregates in water, which were disrupted by adding SDS to the Py-SNP aqueous dispersions. SDS was found to interact with Py-SNPs at SDS concentrations that were close to 2 orders of magnitude lower than its critical micelle concentration (CMC). These interactions led to the breakup of the Py-SNP aggregates, which was confirmed by conducting fluorescence resonance energy transfer experiments between naphthalene-labeled SNPs (Np-SNPs) and Py-SNPs. By the time the SDS concentration reached the CMC of SDS, the Py-SNPs were separated from each other and excimer was generated from isolated Py-SNPs in the aqueous dispersions. Whereas SDS interacted with the Py-SNPs at SDS concentrations lower than CMC, SDS did not seem to target the hydrophobic pyrene aggregates. Only above the CMC did SDS appear to interact with the pyrene aggregates, as evidenced from diffusive pyrene excimer formation between excited and ground-state pyrenes. Most surprisingly, no interaction was observed between sodium dioctyl sulfosuccinate (AOT) and Py-SNP at AOT concentrations where SDS interacted with the Py-SNPs. This observation led to the conclusion that SDS below its CMC interacted not with hydrophobic pyrene aggregates but rather through the formation of inclusion complexes, which led to the electrostatic stabilization of individual Py-SNPs and enabled the breakup of Py-SNP aggregates. The formation of inclusion complexes with linear surfactants like SDS might thus provide a new means of stabilizing hydrophobically modified starch nanoparticles in water, which bears the promise of finding future applications.

Structural, microrheological and kinetic properties of a ternary silica-Pluronic F127-starch thermosensitive system

HYPOTHESIS

The sol-gel transition in aqueous suspensions consisting of silica particles and thermosensitive polymer is controlled by inter-particle forces and solution properties of the polymer. Addition of a second non-thermosensitive polymer may affect the transition. The purpose of this work was to characterize the kinetics of the sol-gel transition and to understand the effects of a second non-thermosensitive polymer on the microstructure, using a combination of classical rheology and microrheology.

EXPERIMENTS

Classical rotational rheology as well as two microrheology methods, Multiple Particle Tracking (MPT) and Diffusing Wave Spectroscopy (DWS), were used to investigate the sol-gel transition of a ternary silica-Pluronic F127-starch thermosensitive system.

FINDINGS

Classical rheometry and DWS indicated sol-gel transition temperature ∼25 °C at 1 wt% Pluronic, independently of the concentration of the other components. DWS showed a fast gelation process, less than two minutes for all samples, beside a second slow kinetic process. In the gel state, MPT indicated micro-structural and micro-viscoelastic differences compared to rotational rheology. This was explained by formation of an elastic matrix of silica and polymers in combination with assembly of silica particles in large macroporous agglomerates. Presence of starch led to breakdown of the macroporous network, leaving the homogeneous elastic network left.

Enhancement of oral bioavailability of magnolol by encapsulation in mixed micelles containing pluronic F127 and L61

OBJECTIVES

We aimed to prepare novel magnolol-loaded mixed micelles (MAG-M) by pluronic F127 and L61 to overcome the challenges of magnolol's poor solubility and then further improve its oral bioavailability.

METHODS

Magnolol-loaded mixed micelles containing pluronic F127 and L61 were prepared by an organic solvent evaporation method. Physicochemical, transport experiment across Caco-2 cell monolayers and pharmacokinetic studies were performed to characterize MAG-M and to determine the final improvement of the oral bioavailability.

KEY FINDINGS

The MAG-M solution was transparent and colourless with average size, polydispersity index and zeta potential of 228.0 ± 2.1 nm, 0.298 ± 0.012 and -0.89 ± 0.02 mV. The micelle solution has a higher EE% and DL% of 81.57 ± 1.49% and 27.58 ± 0.53%, respectively. TEM result showed that the morphology of MAG-M was homogeneous and spherical shape. The dilution stability of MAG-M was no significant change in particle size and entrapment efficiency. MAG was demonstrated a sustained-release behaviour after encapsulated in micelles. MAG permeability across a Caco-2 cell monolayer was enhanced, and the pharmacokinetics study of MAG-M showed a 2.83-fold increase in relative oral bioavailability compared with raw MAG.

CONCLUSIONS

The mixed micelles containing pluronic F127 and L61 as drug delivery system provided a well strategy for resolving the poor solubility and bioavailability problems of MAG.