Diffusion of curcumin in PLGA-based carriers for drug delivery: a molecular dynamics study

CONTEXT

The rapid growth and diversification of drug delivery systems have been significantly supported by advancements in micro- and nano-technologies, alongside the adoption of biodegradable polymeric materials like poly(lactic-co-glycolic acid) (PLGA) as microcarriers. These developments aim to reduce toxicity and enhance target specificity in drug delivery. The use of in silico methods, particularly molecular dynamics (MD) simulations, has emerged as a pivotal tool for predicting the dynamics of species within these systems. This approach aids in investigating drug delivery mechanisms, thereby reducing the costs associated with design and prototyping. In this study, we focus on elucidating the diffusion mechanisms in curcumin-loaded PLGA particles, which are critical for optimizing drug release and efficacy in therapeutic applications.

METHODS

We utilized MD to explore the diffusion behavior of curcumin in PLGA drug delivery systems. The simulations, executed with GROMACS, modeled curcumin molecules in a representative volume element of PLGA chains and water, referencing molecular structures from the Protein Data Bank and employing the CHARMM force field. We generated PLGA chains of varying lengths using the Polymer Modeler tool and arranged them in a bulk-like environment with Packmol. The simulation protocol included steps for energy minimization, T and p equilibration, and calculation of the isotropic diffusion coefficient from the mean square displacement. The Taguchi method was applied to assess the effects of hydration level, PLGA chain length, and density on diffusion.

RESULTS

Our results provide insight into the influence of PLGA chain length, hydration level, and polymer density on the diffusion coefficient of curcumin, offering a mechanistic understanding for the design of efficient drug delivery systems. The sensitivity analysis obtained through the Taguchi method identified hydration level and PLGA density as the most significant input parameters affecting curcumin diffusion, while the effect of PLGA chain length was negligible within the simulated range. We provided a regression equation capable to accurately fit MD results. The regression equation suggests that increases in hydration level and PLGA density result in a decrease in the diffusion coefficient.

Theoretical study of interaction between temozolomide anticancer drug and hydroxyethyl carboxymethyl cellulose nanocarriers for targeted drug delivery by DFT quantum mechanical calculation

In this article for the first time the quantum calculations of 3-methyl-4-oxoimidazo[5,1-d][1,2,3,5]tetrazine-8-carboxamide (Temozolomide) in HCM-Cellulose Substrate are evaluated using the B3LYP/6-31G level of theory. The non-bonded interaction effects of the molecule Temozolomide, HCM-Cellulose on the electronic properties, chemical shift tensors and natural charge have also been detected. Natural bond orbital analysis (NBO) suggests that Temozolomide as an electron donor and HCM-Cellulose acted as an electron acceptor in the Temozolomide/HCM-Cellulose complex. The electronic spectra of the Temozolomide drug and Temozolomide/HCM-Cellulose complex in were calculated by Time-Dependent Density Functional Theory (TD-DFT) for the investigation of the adsorption effect of the Temozolomide drug over HCM-Cellulose on maximum wavelength. As a result, the feasibility of using HCM-Cellulose to deliver Temozolomide to diseased cells has been established.

Aggregation patterns of curcumin and piperine mixtures in different polar media

This work reports a thorough molecular dynamics investigation on the aggregation patterns of curcumin and piperine in water, ethanol and a mixture of both solvents. The low solubility of curcumin in water results in a rapid formation of very stable dimers for both keto and enol tautomers. In agreement with a higher solubility, piperine molecules move closer and farther apart several times during the simulation, which indicates the formation of a less stable dimer in water. In contrast, both curcumin and piperine are soluble in ethanol and, thus, dimers can hardly be formed in this media. In comparison with a pure-water solvent, a 30 : 70 mixture of ethanol and water significantly reduces the probability of formation of most dimers of curcumin and piperine molecules. The simulations show that larger clusters may be complex structures, but the formation of stacks (in the case of piperine and enol tautomer of curcumin) and cages (when the keto tautomer of curcumin is involved) are not rare. Furthermore, it is shown that each single molecule presents a certain degree of mobility in the cluster, especially on the surface, but without leading to dissociation.

A molecular dynamics study on adsorption mechanisms of polar, cationic, and anionic polymers on montmorillonite

Adsorption of polymers on clay in aqueous solutions has wide applications in environmental, medical, and energy-related areas, but the interactions between polymers and clay under varied conditions are still not fully understood. In this study, we investigated the adsorption mechanisms of four polymers belonging to different categories, namely anionic poly(acrylic acid) (poly-AA), cationic poly(diallyldimethylammonium chloride) (poly-DADMAC), nonionic polyacrylamide (poly-AM), and the copolymer of AA and DADMAC (poly-AADADMAC). By using molecular dynamics simulations, we compared the desorption kinetics of these polymers at different temperatures and found that poly-AA and poly-AM have the weakest and strongest adsorption abilities, respectively. Polymer adsorptions are slightly more stable at higher pressures, and high salinity favors the adsorption of charged polymers. Further analysis suggests that the adsorption of anionic poly-AA is less stable than that of cationic poly-DADMAC because the latter is attracted to the negatively charged surface by direct coulombic forces, and poly-AM is stabilized by van der Waals forces and hydrogen bonds. This study provides insights on how to enhance the adsorption affinity of polymers on a clay surface and may help the design or improvement of polymer/clay nanocomposite materials.

Application of DFT Calculations in Designing Polymer-Based Drug Delivery Systems: An Overview

Drug delivery systems transfer medications to target locations throughout the body. These systems are often made up of biodegradable and bioabsorbable polymers acting as delivery components. The introduction of density functional theory (DFT) has tremendously aided the application of computational material science in the design and development of drug delivery materials. The use of DFT and other computational approaches avoids time-consuming empirical processes. Therefore, this review explored how the DFT computation may be utilized to explain some of the features of polymer-based drug delivery systems. First, we went through the key aspects of DFT and provided some context. Then we looked at the essential characteristics of a polymer-based drug delivery system that DFT simulations could predict. We observed that the Gaussian software had been extensively employed by researchers, particularly with the B3LYP functional and 6-31G(d, p) basic sets for polymer-based drug delivery systems. However, to give researchers a choice of basis set for modelling complicated organic systems, such as polymer–drug complexes, we then offered possible resources and presented the future trend.

Mechanism Study on Nanoparticle Negative Surface Charge Modification by Ascorbyl Palmitate and Its Improvement of Tumor Targeting Ability

Surface charge polarity and density influence the immune clearance and cellular uptake of intravenously administered lipid nanoparticles (LNPs), thus determining the efficiency of their delivery to the target. Here, we modified the surface charge with ascorbyl palmitate (AsP) used as a negatively charged lipid. AsP-PC-LNPs were prepared by dispersion and ultrasonication of AsP and phosphatidylcholine (PC) composite films at various ratios. AsP inserted into the PC film with its polar head outward. The pKa for AsP was 4.34, and its ion form conferred the LNPs with negative surface charge. Zeta potentials were correlated with the amount and distribution of AsP on the LNPs surface. DSC, Raman and FTIR spectra, and molecular dynamics simulations disclosed that AsP distributed homogeneously in PC at 1−8% (w/w), and there were strong hydrogen bonds between the polar heads of AsP and PC (PO2−), which favored LNPs’ stability. But at AsP:PC > 8% (w/w), the excessive AsP changed the interaction modes between AsP and PC. The AsP−PC composite films became inhomogeneous, and their phase transition behaviors and Raman and FTIR spectra were altered. Our results clarified the mechanism of surface charge modification by AsP and provided a rational use of AsP as a charged lipid to modify LNP surface properties in targeted drug delivery systems. Furthermore, AsP−PC composites were used as phospholipid-based biological membranes to prepare paclitaxel-loaded LNPs, which had stable surface negative charge, better tumor targeting and tumor inhibitory effects.

A novel pH-responsive nanoniosomal emulsion for sustained release of curcumin from a chitosan-based nanocarrier: emphasis on the concurrent improvement of loading, sustained release, and apoptosis induction

Curcumin application as an anti-cancer drug is faced with several impediments. This study has developed a platform that facilitates the sustained release of curcumin, improves loading efficiency, and anti-cancer activity. Montmorillonite (MMT) nanoparticles were added to chitosan (CS)-agarose (Aga) hydrogel and then loaded with curcumin (Cur) to prepare a curcumin-loaded nanocomposite hydrogel. The loading capacity increased from 63% to 76% by adding MMT nanoparticles to a chitosan-agarose hydrogel. Loading the fabricated nanocomposite in the nanoniosomal emulsion resulted in sustained release of curcumin under acidic conditions. Release kinetics analysis showed diffusion and erosion are the dominant release mechanisms, indicating non-fickian (or anomalous) transport based on the Korsmeyer-Peppas model. FTIR spectra confirmed that all nanocomposite components were present in the fabricated nanocomposite. Besides, XRD results corroborated the amorphous structure of the prepared nanocomposite. Zeta potential results corroborated the stability of the fabricated nanocarrier. Cytotoxicity of the prepared CS-Aga-MMT-Cur on MCF-7 cells was comparable to that of curcumin-treated cells (p <0.001). Moreover, the percentage of apoptotic cells increased due to the enhanced release profile resulting from the addition of MMT to the hydrogel and the incorporation of the fabricated nanocomposite into the nanoniosomal emulsion. To recapitulate, the current delivery platform improved loading, sustained release, and curcumin anti-cancer effect. Hence, this platform could be a potential candidate to mitigate cancer therapy restrictions with curcumin. This article is protected by copyright. All rights reserved.

Preparation and Characterization of TCPP-CaMMT Nanocompound and Its Composite with Polypropylene

Based on the molecular dynamics method, the tris-(1-chloropropan-2yl) phosphate (TCPP)/montmorillonite (MMT) molecular model was established to study the binding energy and microstructure changes in TCPP and MMT. The theoretical simulation results showed that TCPP can enter the MMT layer and increase the layer spacing. From this, an organic intercalated Ca-montmorillonite TCPP-CaMMT was prepared by a very simple direct mixing method using flame retardant TCPP as a modifier. Polypropylene (PP) composites were prepared by TCPP, CaMMT, and TCPP-CaMMT. The microstructures of TCPP-CaMMT nanocompounds and PP composites were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The results showed that TCPP-CaMMT nanocompounds could be exfoliated into nanosheets in PP. The flame retardancy and mechanical properties of PP/TCPP-CaMMT samples were studied by limited oxygen index (LOI) measurements and tensile tests. The PP/TCPP-CaMMT composites showed better LOI, tensile strength, and elongation at break than the machine-mixed PP/TCPP + CaMMT.

Biomolecular engineering of drugs loading in Riboflavin-targeted polymeric devices: simulation and experimental

The synthesis of polymeric nanoparticles (NPs) with efficient drug loading content and targeting moieties is an attractive field and remains a challenge in drug delivery systems. Atomistic investigations can provide an in-depth understanding of delivery devices and reduce the number of expensive experiments. In this paper, we studied the self-assembly of poly (lactic-co-glycolic acid)-b-poly (ethylene glycol) with different molecular weights and surface compositions. The innovation of this molecular study is the loading of an antitumor drug (docetaxel) on a targeting ligand (riboflavin). According to this work, a novel, biocompatible and targeted system for cancer treatment has been developed. The obtained results revealed a correlation between polymer molecular weight and the stability of particles. In this line, samples including 20 and 10 w/w% moiety NPs formed from polymers with 3 and 4.5 kDa backbone sizes, respectively, are the stable models with the highest drug loading and entrapment efficiencies. Next, we evaluated NP morphology and found that NPs have a core/shell structure consisting of a hydrophobic core with a shell of poly (ethylene glycol) and riboflavin. Interestingly, morphology assessments confirmed that the targeting moiety located on the surface can improve drug delivery to receptors and cancerous cells. The developed models provided significant insight into the structure and morphology of NPs before the synthesis and further analysis of NPs in biological environments. However, in the best cases of this system, Dynamic Light Scattering (DLS) tests were also taken and the results were consistent with the results obtained from All Atom and Coarse Grained simulations.

Enhancing the Kinetic Stability of Polymeric Nanomicelles (PLGA) Using Nano-Montmorillonite for Effective Targeting of Cancer Tumors

The toxic profile of chemical cross-linkers used in enhancing the stability of self-assembled nanomicelles made of amphiphilic polymeric materials hinders their use in clinical applications. This study was aimed to use the layered structure of Na-montmorillonite (MMT) as a stabilizer for nanomicelles made of poly(d,l-lactide-co-glycolide) (PLGA) amphiphilic polymer. The size of Na-MMT was reduced below 40 nm (nano-MMT) by processing in an attritor prior to its incorporation with PLGA. Hybrid PLGA nano-MMT (PM) nanoparticles (NPs) were prepared using dialysis nanoprecipitation. The size distribution was measured using dynamic light scattering (DLS). Loading 1250 μg of the model drug molecule curcumin to PM (PMC) resulted in obtaining 88 nm-sized particles, suitable for passive targeting of cancer tumors. The structure of nano-MMT and its position in PMC were investigated using FT-IR, differential scanning chalorimetry (DSC), XRF, XRD, ESEM, and EDAX assays, all of which showed the exfoliated structure of nano-MMT incorporated with both hydrophilic and hydrophobic blocks of PLGA. Curcumin was mutually loaded to PLGA and nano-MMT. This firm incorporation caused a serious extension in the release of curcumin from PMC compared to PLGA (PC). Fitting the release profile to different mathematical models showed the remarkable role of nano-MMT in surface modification of PLGA NPs. The ex vivo dynamic model showed the enhanced stability of PMC in simulated blood flow, while cytotoxicity assays showed that nano-MMT does not aggravate the good toxic profile of PLGA but improves the anticancer effect of payload. Nano-MMT could be used as an effective nontoxic stabilizer agent for self-assembled NPs.

Formulation design and mechanism study of hydrogel based on computational pharmaceutics theories

Formulation design and mechanism study of the drug delivery system (DDS) is an important but difficult subject in pharmaceutical research. The study of formulation factors is the most time- and labor-consuming work of formulation design. In this paper, a multiscale computational pharmaceutics strategy was developed to guide the systematic study of formulation factors of a typical polymer-based DDS, hydrogel, and further to guide the formulation design. According to the strategy, the combination of solubility parameter (δ) and diffusion coefficient (D) calculated by the AA-MD simulation was suggested as the general evaluation method for the matrix screening of the hydrogels at the pre-formulation stage. At the formulation design stage, the CG-MD simulation method was suggested to predict the morphology and drug-releasing behavior of the hydrogels under different formulation factors. The influence mechanism can be explained by the combination of multiple parameters, such as the microstructure diagram, the radius of gyration (Rg), the radial distribution function (RDF), and the free diffusion volume (V_diffusion). The simulation results are in good agreement with the in vitro release experiment, indicating that the strategy has good applicability.

Molecular structure, interactions, and antimicrobial properties of curcumin-PLGA Complexes-a DFT study

Density functional calculations are performed to study the molecular structure, interactions, and antimicrobial activity of curcumin-poly lacto glycolic acid (Cur-PLGA) complexes. The calculations are performed on curcumin (Cur), glycolic acid (SSC and AAT conformers), lactic acid (LA), Cur-SSC, Cur-AAT, Cur-LA, and Cur-PLGA complexes using dispersion corrected M06-2X functional with 6-31 + G* basis set. The condensed Fukui functions of Cur are calculated to identify the favorable reactive sites. Inter- and intramolecular H-bond interactions are analyzed in detail through natural bond orbital, Atoms in Molecule, and Reduced density gradient analyses. The interaction energy values indicate that the interaction between Cur and AAT is stronger than the other studied complexes. Further, our calculations show that the PLGA interacted with Cur is having lower LUMO energy and density values. This indicates that the antimicrobial activity is high in this complex.

Montmorillonite colloid plates with adsorbed cytochrome c: in vitro cytotoxic effect on colon cancer cell culture

Background

The apoptosis (a cascade of biochemical reactions leading to suicide of damaged biological cells) is blocked in the cancer cells because of impossibility of cytochrome c (cytC) go out from the mitochondria. However, the apoptosis can be started by introducing of exogenous cytC into cytoplasm using colloid particles as a protein carrier due to ability of the cancer cells to phagocytize extracellular particles with submicron size.

Results

The clay mineral montmorillonite (MM) were used to prepare aqueous suspension of protein/mineral composite particles by electrostatic adsorption of the positively charged cytC globules on the negatively charged MM colloid plates, and then added to colon cancel culture. The results shows out that separately cytC and MM have no effect but the composite cytC-MM particles kill 95% of the cancer cells after 96 h treatment using equine cytC which is 97% structurally identical with the human cytC. To reach this high cytotoxicity we have formulated requirements to: (a) bare colloid particles (electric charge, form and size), (b) conditions for protein adsorption (concentrations, pH, ionic strength), and (c) suspension with the composite particles (positive total charge and optimal concentration). Due to satisfying these requirements we have reached cytotoxicity which is 1/3 higher than the reached by other authors using different artificial particles. The cytotoxicity rapidly increases with concentration of the cytC-MM particles but further it shows tendency to saturation.

Methods

The optimal pH 6.5 and the 10:3 mg/mg cytC/MM concentration ratio at adsorption were found out by employing computer (protein electrostatics) and physicochemical methods (microelectrophoresis and colloid electrooptics) to prepare cytC-MM suspension. The anticancer capability of cytC-MM nanoplates were investigated using cell culture of metastasizing colon cancer.

Conclusion

The in vitro experiments with colon cancer cell culture disclose that cytC-MM composite particles have potential for application in anticancer therapy of superficial neoplasms of the skin and the alimentary system (mouth cavity, esophagus, stomach, jejunum and colon).

Graphic abstract

Magnetic κ-carrageenan/chitosan/montmorillonite nanocomposite hydrogels with controlled sunitinib release

This work aimed to design montmorillonite-incorporated pH-responsive and magnetic κ-carrageenan/chitosan hydrogels via a completely green route for controlled release of sunitinib anticancer drug. This was accomplished by ionic cross-linking of two biopolymers, κ-carrageenan and chitosan, in the presence of magnetic montmorillonite (mMMt) nanoplatelets. Interestingly, it was observed that the amount of mMMt affected not only the microstructure of hydrogels, but also the drug loading efficiency of nanocomposite hydrogels was noticeably increased by introducing mMMt (from 69 to 96%). The in vitro sunitinib release experiments showed that a low content of loaded sunitinib was released from all hydrogels in the buffered solution with pH 7.4. In contrast, a relatively sustained release with a high content of drug release was observed in the acidic solution of pH 5.5. During 48 h, the hydrogels nanocomposite containing a high content of mMMt showed cumulative release of 64.0 and 8.6% at pH 5.5 and 7.4, respectively. During two days, while the cumulative release of sunitinib was obtained 84.3% for the magnetic-free hydrogel, the magnetic ones showed 74.4 and 64% with the low and high contents of magnetic MMt, respectively. The developed κ-carrageenan/chitosan hydrogels with a high capacity of drug loading and subsequent pH-sensitive drug release can be considered in prolonged cancer therapy with reduced side effects.

Filgrastim loading in PLGA and SLN nanoparticulate system: a bioinformatics approach

OBJECTIVE

In this research work, we hypothesized to predict the nanoparticulate system, best suited for targeted delivery of filgrastim. Significance: Targeted delivery of filgrastim to bone marrow is required to decrease the incidence of neutropenia/febrile neutropenia. This is achieved by nanoparticulate systems, duly designed by bioinformatics approach.

METHOD

The targeted delivery of filgrastim in nanoparticulate system was achieved by molecular dynamics (MD) simulation studies. Two matrices comprising PLGA and SLN (tripalmitin, core component of SLN system) were modeled separately with proposed drug filgrastim. Energy minimization of all systems was done using the steepest descent method. PLGA and tripalmitin systems were equalized at 310 °C, at 1 bar pressure with Berendsen barostat for 200 ps using a v-rescale thermostat for 100 ps. Atomistic MD simulations of four model system and mass density of interacting systems were calculated.

RESULTS

The mass density maps of each nanoparticle system, that is, PLGA and tripalmitin showed an increase in density toward the end of the simulation. The contact numbers attained equilibria with the average number of approx.. 1500 contacts in case of tripalmitin-filgrastim system. While PLGA-filgrastim system shows lesser contacts as compared to tripalmitin with average contacts of approx. 1000.The binding free energy was predicted to be -1104 kJ/mol in tripalmitin-filgrastim complex and -421 kJ/mol in PLGA-filgrastim system.

CONCLUSION

Findings of study revealed that both nanoparticle systems assumed to be good model for drug-carrier systems. Though SLN systems were thought to be more appropriate than PLGA, still the in vivo findings could ascertain this hypothesis in futuristic work.

Periodic DFT Calculations-Review of Applications in the Pharmaceutical Sciences

In the introduction to this review the complex chemistry of solid-state pharmaceutical compounds is summarized. It is also explained why the density functional theory (DFT) periodic calculations became recently so popular in studying the solid APIs (active pharmaceutical ingredients). Further, the most popular programs enabling DFT periodic calculations are presented and compared. Subsequently, on the large number of examples, the applications of such calculations in pharmaceutical sciences are discussed. The mentioned topics include, among others, validation of the experimentally obtained crystal structures and crystal structure prediction, insight into crystallization and solvation processes, development of new polymorph synthesis ways, and formulation techniques as well as application of the periodic DFT calculations in the drug analysis.

pH-sensitive loading/releasing of doxorubicin using single-walled carbon nanotube and multi-walled carbon nanotube: A molecular dynamics study

BACKGROUND AND OBJECTIVE

Doxorubicin is one of the drugs used to treat cancer, and many studies have been conducted to control its release. In this study, carbon nanotubes have been proposed as a doxorubicin carrier, and the effect of carboxyl functional group on the controlled release of doxorubicin has been studied.

METHODS

This study has been done by molecular dynamics simulation and was based on changing the pH as a mechanism controller.

RESULTS

This work is intended to test the efficacy of this drug carrier for the release of doxorubicin. A comparison was also made between single-walled and double-walled carbon nanotubes to answer the question of which one can be a better carrier for doxorubicin. The study of DOXORUBICIN adsorption and release showed that the DOXORUBICIN adsorption on single-walled carbon nanotube and multi-walled carbon nanotube in neutral pH was stronger than it was in acidic pH, which could be due to the electrostatic interactions between the carboxyl group of nanotubes and DOXORUBICIN. Based on this and according to the investigation of hydrogen bonds, diffusion coefficients, and other results it was clear that the drug release in acidic pH was appropriate for body conditions. Since cancer tissues pH is acidic, this shows the suitability of carbon nanotube in drug delivery and DOXORUBICIN release in cancer tissues. In addition, it was shown that the blood pH (pH = 7) is suitable for DOXORUBICIN loading on the carbon nanotube and carbon nanotube-DOXORUBICIN linkage remained stable at this pH; accordingly, the carbon nanotube could deliver DOXORUBICIN in blood quite well and release it in cancerous tissues. This suggests the carbon nanotubes as a promising drug carrier in the cancer therapy which can be also investigated in experiments.

CONCLUSION

It was revealed that the bonds between multi-walled carbon nanotube and DOXORUBICIN was stronger and this complex had a slower release in the cancer tissues compared to the single-walled carbon nanotube; this can be regarded as an advantage over the single-walled carbon nanotube in the DOXORUBICIN delivery and release.

Coating Mechanism of AuNPs onto Sepiolite by Experimental Research and MD Simulation

The amenability of gold nanoparticles (AuNPs) coating on natural and modified (hexadecyl trimethyl ammonium bromide, CTAB) sepiolite surfaces was studied both experimentally and theoretically. The zeta potential experiments and Fourier transform infrared spectrophotometer (FTIR), environmental scanning electron microscope (ESEM), and transmission electron microscopy (TEM) analyses were carried out with the sepiolite samples in the presence of AuNPs. In addition, the adsorption of three gold-nanoparticles on the sepiolite surface (100) in the absence and presence of CTAB was investigated by molecular dynamics (MD) simulations. The AuNPs showed no significant change in the zeta potential of natural sepiolite surfaces due to negative charges of both the sepiolite and AuNPs at natural pH. The surface charge of modified sepiolite decreased with the increase in AuNPs concentration indicating the significance AuNPs adsorption. FTIR, ESEM, and TEM analyses indicated the coating of AuNPs onto the modified sepiolite surface were higher than that of the natural sepiolite surface. The MD simulation results showed that AuNPs can easily adsorb onto the basal surface of the sepiolite due to its hydrophilicity in the presence and absence of CTAB as indicated in the experimental studies. In short, the modification of sepiolite with CTAB made the charge positive, and in turn considerably increased the AuNPs coating on sepiolite surfaces due to electrostatic attraction.

The Effect of Curcumin on the Differentiation of Mesenchymal Stem Cells into Mesodermal Lineage

Curcumin has been placed at the forefront of the researcher's attention due to its pleiotropic pharmacological effects and health benefits. A considerable volume of articles has pointed out curcumin's effects on the fate of stem cell differentiation. In this review, a descriptive mechanism of how curcumin affects the outcome of the differentiation of mesenchymal stem cells (MSCs) into the mesodermal lineage-i.e., adipocyte, osteocyte, and chondrocyte differentiation-is compiled from the literature. The sections include the mechanism of inhibition or induction of MSCs differentiation to each lineage, their governing molecular mechanisms, and their signal transduction pathways. The effect of different curcumin doses and its structural modifications on the MSCs differentiation is also discussed.

Curcumin-loaded electrospun polycaprolactone/montmorillonite nanocomposite: wound dressing application with anti-bacterial and low cell toxicity properties

Materials and scaffolds with antimicrobial properties are of great importance in wound dressing and other tissue engineering applications. The objective of the present work was to fabricate scaffolds made from nanocomposites of polycaprolactone (PCL) and quaternary ammonium salt-modified montmorillonite (MMT) by the electrospinning technique, and then characterize their antimicrobial and other properties for wound dressing applications. The effect of MMT on the structure, morphology, and thermal behavior of the electrospun wound dressings was assessed by means of X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM); the swelling capacity, antibacterial activity, and cytotoxicity were also evaluated. The results of XRD and SEM analyses showed MMT was successfully incorporated into the PCL polymeric matrix and its inclusion reduced the size and thickness of the electrospun fibers compared to pure PCL fibers. The TGA results illustrated an increase in the thermal stability of nanocomposites upon incorporation of nanoclay into the PCL matrix. The swelling capacity of the wound dressings was reduced by increasing the amount of MMT in the PCL matrix due to the increased hydrophobicity of the original MMT resulting from its modification with quaternary ammonium salt. The in vitro curcumin (Cur) release profile revealed an initial burst release followed by a sustained release, with the burst release level reduced by the introduction of MMT into the polymeric matrix. Increasing the nanoclay content further reduced the curcumin release, with the PCL/20% MMT/Cur dressings having the lowest curcumin release of all those tested. The beneficial effect of MMT on the antibacterial behavior of electrospun wound dressings based on PCL/MMT nanocomposites was confirmed, with the introduction of both MMT and curcumin into the PCL matrix resulting in lower bacterial viability. PCL/10% MMT/Cur demonstrated higher antimicrobial activity and the greatest bacterial colony reduction compared to both pure PCL and PCL/10% MMT. The cytotoxicity evaluation indicated low toxicity and confirmed the potential of PCL/MMT nanocomposite scaffolds for wound dressing applications.

Theoretical Study of the Adsorption Process of Antimalarial Drugs into Acrylamide-Base Hydrogel Model Using DFT Methods: The First Approach to the Rational Design of a Controlled Drug Delivery System

The interaction between three widely used antimalarial drugs chloroquine, primaquine and amodiaquine with acrylamide dimer and trimer as a hydrogel model, were studied by means of density functional theory calculation in both vacuum and water environments, using the functional wb97xd with 6-31++G(d,p) basis set and polarizable continuum model (C-PCM) of solvent. According to binding energy, around −3.15 to −11.91 kJ/mol, the interaction between antimalarial compounds and hydrogel model are exothermic in nature. The extent of interaction found is primaquine > amodiaquine > chloroquine. The natural bond orbital (NBO) calculation and application of second-order perturbation theory show strong charge transfer between the antimalarial and hydrogel model. In addition, the results suggest these interactions are polar in nature, where hydrogen bonds play a principal role in stabilization of the complex. Comparing with the gas-phase, the complexes in the water environment are also stable, with suitable values of Log P (Partition coefficient), and dipolar momentum. Consequently, these results encourage to test acrylamide hydrogels as antimalarial delivery systems.

Functional Carboxymethylcellulose/Zein Bionanocomposite Films Based on Neomycin Supported on Sepiolite or Montmorillonite Clays

The present work introduces new functional bionanocomposite materials based on layered montmorillonite and fibrous sepiolite clays and two biopolymers (carboxymethylcellulose polysaccharide and zein protein) to produce drug-loaded bionanocomposite films for antibiotic topical delivery. Neomycin, an antibiotic indicated for wound infections, was employed as the model drug in this study. The physical properties and the antimicrobial activity of these materials were evaluated as a function of the type of hybrid and the amount of zein protein incorporated in the bionanocomposite films. In addition, the interfacial and physicochemical properties of these new clay-drug hybrids have been studied through a combination of experimental and computational methodologies, where the computational studies confirm the intercalation of neomycin into the montmorillonite layers and the possible penetration of the drug in the tunnels of sepiolite, as pointed out by N2 adsorption and X-ray diffraction techniques. The antimicrobial activity of these bionanocomposite materials show that the films based on montmorillonite-neomycin display a more pronounced inhibitory effect of the bacterial growth than those prepared with the sepiolite-neomycin hybrid. Such effect can be related to the difficult release of neomycin adsorbed on sepiolite due to a strong interaction between both components.

The Use of Some Clay Minerals as Natural Resources for Drug Carrier Applications

The goal of modern research is to use environmentally preferable materials. In this context, clay minerals are emerging candidates for their bio- and ecocompatibility, low cost and natural availability. Clay minerals present different morphologies according to their layer arrangements. The use of clay minerals, especially in biomedical applications is known from ancient times and they are regaining attention in recent years. The most representative clay minerals are kaolinit, montmorillonite, sepiolites and halloysite. This review summarizes some clay minerals and their derivatives for application as nanocontainer for biologically active species.

The promoting effect on pre-osteoblast growth under electrical and magnetic double stimulation based on PEDOT/Fe3O4/PLGA magnetic-conductive bi-functional scaffolds

Electrical stimulation (ES) and magnetic stimulation (MS) can promote bone tissue formation in vivo. Loading ES and MS simultaneously would be very beneficial for bone tissue construction in vitro or in vivo. Magnetic-conductive bi-functional scaffolds which are favorable for the transfer of ES and MS, could further facilitate bone cell/tissue growth. Poly(3,4-ethylenedioxythiophene) (PEDOT)/Fe₃O₄/polylactic acid-co-glycolic acid (PLGA) magnetic-conductive bi-functional fibrous scaffolds were prepared through in situ polymerization of EDOT on Fe₃O₄/PLGA fibers. MC3T3-E1 pre-osteoblasts were incubated on the PEDOT/Fe₃O₄/PLGA fibrous scaffolds and were stimulated by electrical, magnetic and electrical-magnetic signals respectively to detect the impact of different stimulation on cell viability. The measured results show that the scaffolds possess good conductivity and superparamagnetic responsiveness. Furthermore, both electrical and magnetic stimulation promoted cell proliferation and magnetic stimulation could induce cell alignment arrangement. Meanwhile, under electrical-magnetic double stimulation, cell viability was much higher than for cells under single electrical or magnetic stimulation. The growth promoting effects of PEDOT/Fe₃O₄/PLGA fibrous scaffolds under electrical-magnetic double stimulation has great practical potential for bone tissue engineering.