Entrapment of Papain in Chitosan-Polyethylene Glycol Hybrid Nanohydrogels: Presenting a Model for Protein Delivery Systems

In this study, the process of manufacturing nanohydrogels containing papain and how to release it was investigated. Chitosan nanohydrogels and chitosan-polyethylene glycol hybrid nanohydrogels were used to entrapment of papain as a protein model. In order to evaluate and confirm different properties of nanohydrogels such as size, shape, the rate of swelling and flexibility, different methods was used. The maximum amount of papain entrapment was observed in 0.75% concentration of chitosan and 1% concentration of sodium Tripolyphosphate (TPP) as linker. The results of scanning electron microscope (SEM) and X-ray diffraction (XRD) patterns showed that nanohydrogels containing papain on a nano scale are very porous and swollen. Differential scanning calorimetry (DSC) thermograms analysis showed that nanohydrogels have relatively good water absorption capacity. Also, by adding polyethylene glycol to chitosan, the melting temperature of hybrid nanohydrogels decreased and this can be a reason for the formation of flexible structures in these nanohydrogels. In chitosan nanohydrogels, the highest release rate of papain was observed at pH lower than 7 and high temperatures, but by adding polyethylene glycol to the chitosan, in addition to increasing papain release, a proper and continuous release of papain was observed at temperature and pH close to physiological conditions, especially at low ratios of polyethylene glycol. According to the present results, hybrid nanohydrogels can have a good potential in protein delivery systems in terms of structure and release.

Improvement of Fe(Ⅲ)/percarbonate system by molybdenum powder and tripolyphosphate: Co-catalytic performance, low oxidant consumption, pH-dependent mechanism

The homogeneous sodium percarbonate (SPC) systems are limited by narrow pH range, ineffective consumption of oxidant, and weak reusability of catalyst. Herein, molybdenum (Mo) powder and sodium tripolyphosphate (STPP) were selected to overcome these challenges. Sulfamethoxazole (SMX), as a model contaminant, was almost completely degraded in 60 min with higher removal rate (0.1367 min-1) than the Mo or STPP-absent system. In addition, Mo/STPP-Fe(Ⅲ)/SPC system was cost-effective in terms of oxidant consumption, requiring only 0.2 mM SPC. About activation mechanism, the main active species for SMX degradation was pH-dependent, with hydroxyl radical (·OH) as the dominant active species at pHi = 7 and ·OH, carbonate radical (CO3·-), and superoxide radical (O2·-) derived from a series of chain reaction at pHi = 10, respectively. Due to the generation of various electrophilic free radical, the system exhibited excellent performance towards electron-rich pollutants under a wide pH range. Furthermore, Mo exhibited excellent stability and reusability. SMX was degraded through hydroxylation, N-S cleavage, amino and sulfanilamide oxidation into intermediates whose toxicities were evaluated by Toxicity Estimation Software Tool (T.E.S.T.) software. This work provided new insights to Fe/SPC system towards high-efficiency and low consumption treatment of practical application.

Optimize the parameters for the synthesis by the ionic gelation technique, purification, and freeze-drying of chitosan-sodium tripolyphosphate nanoparticles for biomedical purposes

BACKGROUND

Polymeric nanoparticles can be used for wound closure and therapeutic compound delivery, among other biomedical applications. Although there are several nanoparticle obtention methods, it is crucial to know the adequate parameters to achieve better results. Therefore, the objective of this study was to optimize the parameters for the synthesis, purification, and freeze-drying of chitosan nanoparticles. We evaluated the conditions of agitation speed, anion addition time, solution pH, and chitosan and sodium tripolyphosphate concentration.

RESULTS

Chitosan nanoparticles presented an average particle size of 172.8 ± 3.937 nm, PDI of 0.166 ± 0.008, and zeta potential of 25.00 ± 0.79 mV, at the concentration of 0.1% sodium tripolyphosphate and chitosan (pH 5.5), with a dripping time of 2 min at 500 rpm. The most representative factor during nanoparticle fabrication was the pH of the chitosan solution, generating significant changes in particle size and polydispersity index. The observed behavior is attributed to the possible excess of sodium tripolyphosphate during synthesis. We added the surfactants poloxamer 188 and polysorbate 80 to evaluate the stability improvement during purification (centrifugation or dialysis). These surfactants decreased coalescence between nanoparticles, especially during purification. The centrifugation increased the zeta potential to 40.8-56.2 mV values, while the dialyzed samples led to smaller particle sizes (152-184 nm). Finally, freeze-drying of the chitosan nanoparticles proceeded using two cryoprotectants, trehalose and sucrose. Both adequately protected the system during the process, and the sugar concentration depended on the purification process.

CONCLUSIONS

In Conclusion, we must consider each surfactant's benefits in formulations for selecting the most suitable. Also, it is necessary to do more studies with the molecule to load. At the same time, the use of sucrose and trehalose generates adequate protection against the freeze-drying process, even at a 5% w/v concentration. However, adjusting the percentage concentration by weight must be made to work with the CS-TPP NPs purified by dialysis.

Preparation, characterization, and in vitro cytotoxicity activity of allyl-isothiocyanate-embedded polymeric nanoparticles for potential breast cancer targeting

BACKGROUND

Allyl isothiocyanate (AITC) is an excellent active phytoconstituent recently revealed for cancer treatment. The strategic prominence of this study was to synthesize and characterize AITC-embedded tripolyphosphate-modified chitosan nanoparticles (AITC@CS-TPP-NPs) by ionic gelation.

METHOD

Chitosan is recycled as a polymer to fabricate AITC@CS-TPP-NPs; the fabricated nanoparticles (NPs) are then characterized using FT-IR spectroscopy, DSC, XRD, zeta potential, size analysis, SEM, EDX, entrapment efficiency, in vitro drug release study, and in vitro cytotoxicity activity against MCF-7 to explore the effectiveness and strength.

RESULTS

As a result, developed AITC@CS-TPP-NPs demonstrates good stability with a zeta potential of 35.83 mV and 90.14% of drug release. The anticancer potential of AITC@CS-TPP-NPs shows the improved cytotoxicity activity of AITC due to the surface modification of CS using TPP. Hence, the cytotoxicity of AITC@CS-TPP-NPs was tested in vitro against a human breast cancer cell line (MCF-7) and found to be considerable.

CONCLUSION

The AITC@CS-TPP-NPs were effectively synthesized and have significant benefits, including being easy to prepare, stable, and affordable with wide use in human breast cancer against cell line (MCF-7).

Coating with tripolyphosphate-crosslinked chitosan as a novel approach for enhanced stability of emulsomes following oral administration: Rutin as a model drug with improved anti-hyperlipidemic effect in rats

The aim of the current study is to preserve the emulsomal vesicles against the harsh condition of gastrointestinal tract (GIT), after oral administration, employing tripolyphosphate (TPP)-crosslinked chitosan as a protective coating layer. Rutin was used as a model drug with evaluation of anti-hyperlipidemic activity in rats. The rutin loaded unmodified emulsomes were prepared using tripalmitin and soybean phosphatidylcholine (SPC), by thin film method. Drug loading for the prepared formulations ranged between 6.80 and 15.50 %. The selected formulation (RT-Emuls-6) comprised tripalmitin and SPC, molar ratio 1:1, and exhibited particle size (PS) and zeta potential (ZP) of 150.40 nm and -35.35 mV, respectively. RT-Emuls-6 was then modified by coating with either solely chitosan (RT-Emuls-6-Ch) or TPP-crosslinked chitosan (RT-Emuls-6-Ch-TPP-1). The latter exhibited PS and ZP values of 269.60 nm and 37.17 mV, respectively. Transmission electron microscopy of RT-Emuls-6-Ch-TPP-1 showed a dense pale greyish layer of a coating layer of chitosan crosslinked with TPP surrounding SPC bilayers. Fourier transform infrared spectroscopy analysis along with X-ray powder diffraction confirmed cross-linking between chitosan and TPP. Stability study in the simulated GIT fluids revealed that the order of rutin retained percentage was RT-Emuls-6-Ch-TPP-1 > RT-Emuls-6-Ch > RT-Emuls-6 (80.02, 50.66 and 44.41 %, respectively for simulated gastric fluid and 63.50, 55.66 and 24.00 %, respectively for simulated intestinal fluid, after 2 h incubation). Anti-hyperlipidemic activity of rutin loaded emulsomes was evaluated, after oral administration, in a high fat diet-induced hyperlipidemia in rats. The order of activity was as follows: RT-Emuls-6-Ch-TPP-1 > RT-Emuls-6-Ch > RT-Emuls-6 > free rutin. These findings revealed the potential of TPP-crosslinked chitosan as a protective coating layer for enhancing the stability of emulsomes against the harsh condition of GIT. RT-Emuls-6-Ch-TPP-1 had a potent anti-hyperlipidemic activity via regulation of lipids, oxidative stress, irisin and uncoupling protein 1.

Negatively charged chitosan nanoparticles prepared by ionotropic gelation for encapsulation of positively charged proteins

The nanoprecipitation of hydrogel nanoparticles by complex coacervation is investigated through a systematic study of the popular chitosan-polyphosphate pair of polyelectrolytes with opposite charges at pH 4. Polyphosphates of varying molar masses and electrical charges are investigated as alternatives to the commonly used tripolyphosphate, so as to assess the influence of the strength of electrostatic interactions on the fabrication possibility, the size of hydrogel particles, and their overall charge. Sodium hexametaphosphate and sodium polyphosphate allow the manufacture of such nanoparticles with either a positive or a negative charge, depending on the chitosan/polyphosphate ratio and the order of mixing. The classical way of mixing by pouring the polyphosphate solution into the chitosan solution yields microparticles. Inverting the order of mixing by pouring the chitosan solution into the polyphosphate solution allows the precipitation of negatively charged nanoparticles with diameters in the range 100-200 nm. Such charge inversion of the chitosan into negative is not possible with the common TPP. It was achieved using sodium hexametaphosphate and sodium polyphosphate having a larger negative charge. Charge inversion of chitosan allows an efficient encapsulation of positively charged proteins with an improved encapsulation efficiency than in the usual TPP-based coacervate. The encapsulation of the bovine serum albumin at pH 4 is given as a case study of a positively charged protein.

Fabrication and investigation of novel monochloroacetic acid fortified, tripolyphosphate-crosslinked chitosan for highly efficient adsorption of uranyl ions from radioactive effluents

Chitosan crosslinked with potassium tripolyphosphate (CTPP) and monochloroacetic-acid-modified chitosan crosslinked with potassium tripolyphosphate (MCTPP) were synthesized for removing UO₂²⁺ from acidic radioactive effluents. The influential factors, operational requirements, and interactive mechanisms of the adsorption process were systematically investigated. The mesh-structured composites adsorbed UO₂²⁺ most effectively at pH 5.0. The maximum adsorption capacities for pure chitosan, CTPP, and MCTPP were 374.93, 780.89, and 1487.72 mg/g, respectively. Batch experiments indicated that the pH and adsorbent dose strongly influenced UO₂²⁺ adsorption. MCTPP could adsorb most UO₂²⁺ within 15 min, and equilibrium was reached by ~1 h. The adsorption isotherms indicated that UO₂²⁺ adsorption by MCTPP may be an endothermic single-layer adsorption process. Moreover, common metal ions in single-metal systems only slightly affected this process. The results of instrumental characterization and natural water application suggested that the highly developed pore structure and abundant tripolyphosphate groups in synthesized composites were dominant adsorption contributors besides amino and hydroxyl groups. Successful development of the novel material for efficiently adsorbing UO₂²⁺ and identification of the adsorption mechanism will provide valuable guidance to chitosan modification and further remediation practices of radioactive effluents.

Chitosan oleate-tripolyphosphate complex-coated calcium alginate bead: Physicochemical aspects of concurrent core-coat formation

This study designed chitosan species-coated calcium alginate beads through concurrent core-coat formation. Chitosan oleate was synthesized by carbodiimide chemistry and characterized by ¹H NMR and FTIR techniques. Chitosan or chitosan oleate was coated onto the forming alginate or alginate/tripolyphosphate core using vibratory nozzle extrusion-microencapsulation approach, followed by calcium crosslinking. Chlorpheniramine maleate served as a model water-soluble drug. The molecular characteristics, size, shape, morphology, swelling, erosion, water uptake, drug content and drug release profiles of beads were evaluated. Discrete spherical coated beads were obtained through minimizing successive bead adhesion through an interplay of nozzle vibrational frequency and polymeric solution flow rate. The tripolyphosphate ions in the core possessed higher diffusional kinetics than alginate and were better able to attract chitosan species onto bead surfaces to facilitate alginate-chitosan coacervation. Amphiphilic chitosan oleate formed smaller aggregates than chitosan. It interacted with greater ease with core alginate and tripolyphosphate. The gain in alginate/tripolyphosphate interaction with chitosan oleate at the core-coat interface enhanced bead robustness against swelling and water uptake with drug release consequently dependent on the loss of alginate-drug interaction.

Oxidative degradation of phenol by sulfidated zero valent iron under aerobic conditions: The effect of oxalate and tripolyphosphate ligands

After adding either organic or inorganic ligands, sulfidated nano-zero-valent iron (SnZVI) was used for aerobic degradation of phenol, and the effect of the ligand species on oxidation performance was investigated. We found that SnZVI hardly degraded phenol in the absence of ligand addition. Ligands initiated and promoted the degradation of pollutants by SnZVI. The data herein show that a characteristic inorganic ligand, tripolyphosphate (TPP), is more effective in enhancing oxidation than a characteristic organic ligand oxalate. In addition to the scavenging of reactive oxidants by the organic ligand, more ferrous ion (Fe(II)) dissolution from SnZVI in the TPP system is another cause for the superior enhancement by the inorganic ligand. In the oxalate system, as the sulfur content of SnZVI increased, the oxidation efficiency increased because FeS shell promoted the transfer of electrons to produce more reactive oxygen species (ROS). In TPP system, the effect of sulfur content on oxidation performance is more complex. The SnZVI with low sulfur content showed poor oxidation performance compared with that of nZVI. Further experiments proved that sulfidation might weaken the complexation of TPP with surface bound Fe, which would slow down the ionic Fe(II) dissolution rate. Therefore, sulfidation has the dual effects of enhancing electron transfer and inhibiting the complexation of inorganic ligands. In addition, the mechanisms of ROS generation in different ligand systems were investigated herein. Results showed that the critical ROS in both the oxalate and TPP systems are hydroxyl radicals, and that they are produced via one-electron activation of O₂.

Biomolecular uptake effects on chitosan/tripolyphosphate micro- and nanoparticle stability

Colloidal chitosan/tripolyphosphate (TPP) particles have attracted significant attention as potential delivery vehicles for drugs, genes and vaccines. Yet, there have been several fundamental studies that showed these particles to disintegrate at physiological pH and ionic strength levels. To reconcile these findings with the published drug, gene and vaccine delivery research where chitosan/TPP particle disintegration was not reported, it has been postulated that the particles could be stabilized by their bioactive payloads. To test this hypothesis, here we examine whether the association of chitosan/TPP particles with model anionic proteins, α-lactalbumin (α-LA) and bovine serum albumin (BSA), and polynucleotides (DNA) enhances chitosan/TPP particle stability at physiological ionic strengths, using 150 mM NaCl (pH 5.5) and 1× PBS (pH 6.0) as the dissolution media. Light scattering and UV-vis spectroscopy revealed that anionic protein uptake had no impact on particle stability, likely due to the relatively weak protein/particle binding at near-physiological ionic strengths, which caused the protein to be rapidly released. This result occurred regardless of whether the protein was loaded during or after particle formation. Conversely, DNA uptake (at least at some compositions) increased the chitosan fractions persisting in a complexed/particulate form in model dissolution media, with the DNA remaining largely complexed to the chitosan at all investigated conditions. Collectively, these findings suggest that, while most bioactive payloads do not interact with chitosan strongly enough to stabilize chitosan/TPP particles, these chitosan particles can be stabilized to dissolution through the incorporation of polyanions.

PEGylation and folate conjugation effects on the stability of chitosan-tripolyphosphate nanoparticles

Chitosan-based nanoparticles (Ch-NPs) prepared via ionotropic gelation of Ch with sodium tripolyphosphate (TPP) have been widely examined as potential drug carriers. Yet, recent studies have shown these particles to be unstable in model (pH 7.2-7.4) physiological media. To this end, here we explored the possibility of improving TPP-crosslinked Ch-NP stability through chemical Ch modification. Specifically, Ch samples with either 76% or 92% degrees of deacetylation (DD) were grafted with either polyethylene glycol (PEG), a hydrophilic molecule, or folic acid (F), a hydrophobic molecule. Limited variation in dispersion light scattering intensity, particle size and apparent ζ-potential, and lack of macroscopic precipitation were chosen as analytical evidence of dispersion stability. TPP titrations were performed to determine the optimal TPP:glucosamine molar ratio for preparing particles with near 200-nm diameters, which are desirable for systemic administration of drugs, cellular uptake, and enhancing NP blood circulation. Both DD and Ch modification influenced the particle formation process and the evolution in NP size and ζ-potential upon 30-day storage in virtually salt-free water at 25 °C and 37 °C, where the NPs underwent partial aggregation (along with possible dissolution and swelling) but remained colloidally dispersed. Under model physiological (pH 7.2; 163 mM ionic strength) conditions, however (where the chitosan amine groups were largely deprotonated), the particles quickly became destabilized, evidently due to particle dissolution followed by Ch precipitation. Overall, within the degrees of substitution used for this work (~1% for PEG, and 3 and 6% for F), neither PEG nor F qualitatively improved Ch-NP stability at physiological pH 7.2 conditions. Thus, application of TPP-crosslinked Ch-NPs in drug delivery (even when Ch is derivatized with PEG or F) should likely be limited to administration routes with acidic pH (at which these NPs remain stable).

Stabilization of chitosan-based polyelectrolyte nanoparticle cargo delivery biomaterials by a multiple ionic cross-linking strategy

PolyElectrolyte Nanoparticles (PENs) obtained by layer-by-layer self-assembly of polycations/polyanions suffer from a lack of colloidal stability in physiological conditions. We report a simple innovative approach for increasing their stability by multiple ionic cross-linkers. Herein, a chitosan-based core was stabilized by polyanions such as tripolyphosphate and dextran sulfate at pHs of 3 (aPENs) and 8 (bPENs) to improve the quality of electrostatic interactions in the core and manage self-assembly of polyethyleneimine shell onto the core. The physicochemical properties of the particles were characterized by DLS, SEM, TEM, FT-IR, and TGA. TEM micrographs showed visible core/shell structures of bPENs. From particle size and polydispersity indices, the bPENs stability was salt concentration-dependent. The release profiles of PENs using nicotinic acid demonstrated sustained release in a pH-independent manner with a good fit of Korsmeyer-Peppas model. These results suggest that multiple ionic cross-linkers can be an efficient approach to increase the colloidal stability of PENs.

Tripolyphosphate-assisted electro-Fenton process for coking wastewater treatment at neutral pH

The first application of a novel electro-Fenton (EF) for coking wastewater (CW) treatment at the original pH (6.80) by using tripolyphosphate (TPP) ligand was proposed. Total organic carbon (TOC) decay of CW followed a pseudo-first kinetic rate constant with an apparent rate constant (k_app) of 1.07 × 10^-2 min^-1 for the EF in the presence of TPP (EF/TPP), which was 2.10 times higher than that of conventional EF (k_app = 5.10 × 10^-3 min^-1) working at pH 3. The high efficiency of EF/TPP at neutral pH was mainly attributed to the newly formed Fe-O-P coordination in the iron-ligand compound (Fe²⁺-TPP) supported by UV-absorption spectra results, activating oxygen to produce ^•OH and hence enhancing the oxidation capacity. Key operating parameters of CW mineralization by EF/TPP including Fe²⁺ concentration and pH value were systematically investigated. Excitation-emission matrix (EEM) spectra technique was used to assess the variance of dissolved organic matters during the EF/TPP process. Results showed an 81% mineralization of CW after 3 h electrolysis coupled with a low energy consumption (0.129 kWh g^-1 TOC) which were obtained by the EF/TPP process. Microtox toxicity demonstrated that TPP could reduce the toxicity of raw CW and importantly, it showed that EF/TPP was effective for detoxification. Mechanism study via simulated matrix with similar components as CW revealed that ^•OH produced both from Fenton and Fe²⁺-TPP activation together with the generated active chlorine was responsible for CW mineralization. In summary, the TPP-assisted EF process was presented as a promising technique for extending coking wastewater treatment at near-neutral pH with a high mineralization.

Nanoparticles of Chitosan Loaded Ciprofloxacin: Fabrication and Antimicrobial Activity

Purpose: Chitosan is a natural mucoadhesive polymer with antibacterial activity. In the present study, chitosan (CS) nanoparticles were investigated as a vehicle for delivery of antibiotic, ciprofloxacin hydrochloride. Methods: Ionotropic gelation method was used for preparation chitosan nanoparticles. The effects of various factors including concentration of CS, concentration of tripolyphosphate (TPP), and homogenization rate on the size of nanoparticles were studied. The effects of various mass ratios of CS to ciprofloxacin hydrochloride on the encapsulation efficiency of nanoparticles were assessed. Results: The particles prepared under optimal condition of 0.45% CS concentration, 0.45% TPP concentration and homogenizer rate at 6000 rpm, had 72 nm diameter. In these particles with 1:0.5 mass ratio of CS to ciprofloxacin hydrochloride, the encapsulation efficiency was 23%. The antibacterial activity of chitosan nanoparticles and ciprofloxacin-loaded nanoparticles against E.coli and S.aureus was evaluated by calculation of minimum inhibitory concentration (MIC). Results showed that MIC of ciprofloxacin loaded chitosan nanoparticles was 50% lower than that of ciprofloxacin hydrochloride alone in both of microorganism species. Nanoparticles without drug exhibited antibacterial activity at higher concentrations and MIC of them against E.coli and S.aureus was 177 and 277 µg/ml, respectively. Conclusion: Therefore chitosan nanoparticles could be applied as carrier for decreasing the dose of antibacterial agents in the infections.

Preparation of chitosan/tripolyphosphate nanoparticles with highly tunable size and low polydispersity

Nanoparticles prepared through the ionotropic gelation of chitosan with tripolyphosphate (TPP) have been extensively studied as vehicles for drug and gene delivery. Though a number of these works have focused on preparing particles with narrow size distributions, the monodisperse particles produced by these methods have been limited to narrow size ranges (where the average particle size was not varied by more than twofold). Here we show how, by tuning the NaCl concentration in the parent chitosan and TPP solutions, low-polydispersity particles with z-average diameters ranging between roughly 100 and 900nm can be prepared. Further, we explore how the size of these particles depends on the method by which the TPP is mixed into the chitosan solution, specifically comparing: (1) single-shot mixing; (2) dropwise addition; and (3) a dilution technique, where chitosan and TPP are codissolved at a high (gelation-inhibiting) ionic strength and then diluted to lower ionic strengths to trigger gelation. Though the particle size increases sigmoidally with the NaCl concentration for all three mixing methods, the dilution method delivers the most uniform/gradual size increase - i.e., it provides the most precise control. Also investigated are the effects of mixture composition and mixing procedure on the particle yield. These reveal the particle yield to increase with the chitosan/TPP concentration, decrease with the NaCl concentration, and vary only weakly with the mixing protocol; thus, at elevated NaCl concentrations, it may be beneficial to increase chitosan and TPP concentrations to ensure high particle yields. Finally, possible pitfalls of the salt-assisted size control strategy (and their solutions) are discussed. Taken together, these findings provide a simple and reliable method for extensively tuning chitosan/TPP particle size while maintaining narrow size distributions.

Effects of tripolyphosphate on cellular uptake and RNA interference efficiency of chitosan-based nanoparticles in Raw 264.7 macrophages

Tumor necrosis factor-α (TNF-α) is a major pro-inflammatory cytokine that is mainly secreted by macrophages during inflammation. Here, we synthesized a series of N-(2-hydroxy)propyl-3-trimethyl ammonium chitosan chlorides (HTCCs), and then used a complex coacervation technique or tripolyphosphate (TPP)-assisted ionotropic gelation strategy to complex the HTCCs with TNF-α siRNA (siTNF) to form nanoparticles (NPs). The resultant NPs had a desirable particle size (210-279nm), a slightly positive zeta potential (14-22mV), and negligible cytotoxicity against Raw 264.7 macrophages and colon-26 cells. Subsequent cellular uptake tests demonstrated that the introduction of TPP to the NPs markedly increased their cellular uptake efficiency (to nearly 100%) compared with TPP-free NPs, and yielded a correspondingly higher intracellular concentration of siRNA. Critically, in vitro gene silencing experiments revealed that all of the TPP-containing NPs showed excellent efficiency in inhibiting the mRNA expression level of TNF-α (by approximately 85-92%, which was much higher than that obtained using Oligofectamine/siTNF complexes). Collectively, these results obviously suggest that our non-toxic TPP-containing chitosan-based NPs can be exploited as efficient siTNF carriers for the treatment of inflammatory diseases.

In vitro performance of injectable chitosan-tripolyphosphate scaffolds combined with platelet-rich plasma

This study aimed to evaluate the in vitro biological effectiveness of chitosan microparticles crosslinked with sodium tripolyphosphate (TPP) in combination with activated pure platelet-rich plasma (aP-PRP) as an injectable composite scaffold for growth factors release, cell proliferation and osteogenic differentiation. Two main novelties were addressed in the field of scaffolds in regenerative medicine: the first is the approach including simultaneously the three vertices of the proliferation triangle formed by the capabilities genic progenitor cells, conductive scaffolds and inductive growth factors, which are provided by platelet rich plasma (PRP); secondly, the approach of an injectable composite scaffolds formed by the fibrin network from aP-PRP and the chitosan microparticles crosslinked with TPP. The microparticles were prepared by vortexing the chitosan and TPP solutions. The ionic crosslinking of chitosan with TPP was made at mass ratios of 2:1, 5:1, and 10:1 at pH 4.0. P-PRP was obtained via the controlled centrifugation of whole blood. The composite scaffolds were prepared by adding the microparticles to immediately activated P-PRP. The results showed that the microparticles had adequate physicochemical and mechanical properties for injection. Furthermore, the microparticles controlled the release of growth factors from P-PRP. The proliferation of human adipose-derived mesenchymal stem cells was lower than in aP-PRP alone but significant at a 2:1 chitosan-TPP mass ratio. Osteogenic differentiation was stimulated at all studied mass ratios, as indicated by the alkaline phosphatase activity. These results offer perspectives for optimizing the composite scaffold, and to prove its potential as an injectable scaffold in regenerative medicine.

Fabrication, characterization and cytotoxicity studies of ionically cross-linked docetaxel loaded chitosan nanoparticles

The present investigation aimed at the fabrication and characterization of ionically cross-linked docetaxel (DTX) loaded chitosan nanoparticles (DTX-CH-NP) using ionic gelation technique with sodium tripolyphosphate (TPP) as the cross-linking agent. The formulated nanoparticles were characterized in terms of particle size, drug entrapment efficiency (EE), scanning electron microscopy (SEM), in vitro release and cytotoxicity studies. Formulation factors (chitosan, TPP and drug concentration) were examined systematically for their effects on size of the nanoparticles. The average size of the nanoparticles was observed to be in the range of 159.2 ± 3.31 to 220.7 ± 2.23 nm with 78-92% encapsulation efficiency (EE). The in vitro cytotoxicity studies on breast cancer cell lines (MDA-MB-231) revealed the advantages of DTX-CH-NP over pure DTX with approximately 85% cell viability reduction. The results indicate that systematic modulation of the surface charge and particle size of ionically cross-linked nanoparticles can be readily achieved with the right control of critical processing parameters. Thus, DTX-CH-NP presents a promising delivery alternative for breast cancer treatment.

Development and characterization of hydroxyapatite/β-TCP/chitosan composites for tissue engineering applications

Calcium phosphate ceramics that mimic bone composition provide interesting possibilities for the advancement in bone tissue engineering. The present study reports on a chitosan composite reinforced by hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) obtained from waste mussel shells and cross-linked using tripolyphosphate (TPP). The ratios of the ceramic components in composites were 20/10/70, 30/20/50 and 40/30/30 (HA/β-TCP/CH, w/w %). Biodegradation rate, structural properties and in-vitro degradation of the bone-like composite scaffolds were investigated. The optimum amount of TPP required for composite was 2.5% and glycerol was used as plasticizer at an optimized concentration of 1%. Tripolyphosphate cross-linked chitosan composites were developed by freezing and lyophilisation. The Young's modulus of the scaffolds was increased from 4kPa to 17kPa and the porosity of composites dropped from 85 to 68% by increasing the HA/β-TCP ratio. After 28days in physiological solution, bone-like composite scaffolds with a higher ratio of HA/β-TCP (e.g. 40/30/30) showed about 2% lower biodegradation in comparison to scaffolds with a lower ratio of HA/β-TCP (i.e. 20/10/70). The obtained data suggest that the chitosan based bone-like composites could be potential candidates for biomedical applications.

The contribution of household chemicals to environmental discharges via effluents: combining chemical and behavioural data

Increased concentrations and loads of soluble, bioavailable forms of phosphorus (P) are a major cause of eutrophication in streams, rivers and lakes in many countries around the world. To implement P control measures, it is essential to identify P sources and their relative load contributions. A proportion of P loading generated from household wastewaters is derived from detergents yet the P compositions of the range of domestic detergents and their usage is poorly understood. To quantify P loads from household detergents, we analysed a large range of detergents and cleaning products commonly available in the UK and Europe, comparing regular and eco-labelled products. Chemical data were coupled with survey results on typical household detergents preferences and usage (n = 95 households). We also determined whether the major and trace element signatures of these household detergents could potentially be used as anthropogenic tracers in watercourses. The greatest P concentrations were found for regular dishwasher detergents (43-131 mg P/g detergent) whilst the range of P in eco-labelled dishwasher detergents was much lower (0.7-9.1 mg P/g detergent). Other household cleaning groups contained relatively smaller P concentrations. Considering the survey results, detergents' total P loading generated from one household using either regular or eco labelled products, was 0.414 and 0.021 kg P/year, respectively. Given a household occupancy of 2.7, the P load from all detergent use combined was 0.154 kg P/person/year of which the dishwasher contribution was 0.147 kg P/person/year. In terms of elemental signatures, (DWD) dishwasher detergents were significantly (P-value <0.001) different from other household cleaning products in their As, Na, TP, Si, Sr, SRP, Ti, Zn and Zr signatures. Na, P and B were all positively correlated with each other, indicating their potential use as a tracer suite for septic tank effluent in combination with other indices. We conclude that forthcoming legislation for reducing P contents in domestic laundry detergents will not address the dominant environmental P load from DWD and studies such as this are important in promoting and allowing scenarios of benefits from future legislation for DWD.

Microscale scavenging of pentachlorophenol in water using amine and tripolyphosphate-grafted SBA-15 silica: batch and modeling studies

Mesoporous silica SBA-15 meets most criteria for selection of water treatment adsorbents such as high specific surface area, large pore-size, chemical inertness, repertory of surface functional groups, good thermal stability, selectivity, regenerability, and low cost of manufacture. However, its use for water treatment is still largely unexplored. SBA-15 and its functionalized derivatives of aminopropyltriethoxysilane (SA) and tripolyphosphate (ST) were synthesized, characterized, and used to investigate pentachlorophenol (PCP) removal from aqueous solutions. Functionalization improved SBA-15 capacity for PCP removal from solution in accordance with the trend SBA-15 < ST < SA. Sorption rate experiments data fit the Lagergren pseudo-second order kinetics model. Intra-particle diffusion indicated that the sorption is controlled by two mechanisms: intra-particle and equilibrium diffusion. Adsorptive pore-filling and electrostatic interactions were implicated in the removal of PCP from solution. Electrostatic interaction led to ≥75% increase in sorption upon functionalization. The equilibrium sorption data of the PCP on these mesoporous materials fits the Freundlich isotherm. Desorption hysteresis was low for the pristine SBA-15, but the functionalized SBA-15 materials showed higher hysteresis. The results imply that functionalized SBA-15 sorbents are promising materials for microscale scavenging of PCP in solution.

Production of microparticles with gelatin and chitosan

In the past few decades, the textile industry has significantly increased investment in research to develop functional fabrics, with a special focus on those aggregating values. Such fabrics can exploit microparticles inferior to 100 μm, such as those made by complex coacervation in their creation. The antimicrobial properties of chitosan can be attributed to these microparticles. Developing particles with uniform structure and properties would facilitate the control for the eventual release of the core material. Thus, a complex coacervation between gelatin and chitosan was studied, and the optimal conditions were replicated in the encapsulation of limonene. Spherical particles formed had an average diameter (D3,2) of 30 μm and were prepared with 89.7% efficiency. Cross-linking of these microparticles using glutaraldehyde and tripolyphosphate was carried out before spray drying. After drying, microparticles cross-linked with glutaraldehyde were oxidized and clustered and those that were cross-linked with tripolyphosphate resisted drying and presented a high yield.