Entrapment Of Nanoparticles Research Articles

Antibacterial characteristics of TiO2 nano-objects and their interaction with biofilm

The antibacterial activity of as-synthesised TiO2 nanoparticles (NPs) is determined on biofilm formed by Enterobacter sp. (1.25 μm, Gram-negative bacteria). Nano-sized particles were characterised and their biological interaction was studied by electron microscopy images that revealed the complete entrapment of NPs into the mucilaginous polysaccharide of Enterobacter sp. leading to membrane damage at even low concentration of NPs i.e. 700 μg mL−1 under 72 h of incubation. At this condition, the antibacterial characteristic was observed to be the highest as confirmed by calculating the population of bacterial cell growth with respect to concentration of NPs. The mechanism of biological interaction is the formation of NPs agglomerates that are effective in ‘plugging’ the bacterial outermost layer and cause destruction. Our results confirm that nano-sized TiO2 particles are potent inhibitors of bacterial biofilm and thus can be utilised to treat wound infection which is otherwise challenging and is not reported till date.

Surface modification of polyurethane via creating a biocompatible superhydrophilic nanostructured layer: role of surface chemistry and structure

ABSTRACTAdvanced surface modification approaches of biomaterials alongside the advent of sophisticated analytical techniques have provided a great opportunity to understand how the physicochemical characteristics of materials determine cell–surface dynamics at molecular and atomic scale. However, there are still many contradictory reports, which are mainly due to inadequate information about the role of the two parameters of surface chemistry and structure and their synergistic effect as an adequate predictor of biological performance. Here, surface parameters were altered by grafting of poly ethylene glycol (PEG) on polyurethane (PU) surfaces through a superhydrophilic modification method. In this study, surface modification of PU films by PEG thin layer via grafting technique and TiO2 nanoparticle entrapment in the brush polymers was investigated. The surface modification led to a reduction in protein adsorption and bacterial attachment by 8.7 times and 71% respectively with no cytotoxicity effect on HeLa cells. It was also observed that when PU surface became superhydrophilic the bacterial adhesion becomes independent of bacterium type. In general, it was observed that the impact of topographical changes on the biocompatibility and biofilm formation becomes significantly more profound than that of the surface chemistry alteration.

Short peptide based nanotubes capable of effective curcumin delivery for treating drug resistant malaria.

BackgroundCurcumin (Ccm) has shown immense potential as an antimalarial agent; however its low solubility and less bioavailability attenuate the in vivo efficacy of this potent compound. In order to increase Ccm’s bioavailability, a number of organic/inorganic polymer based nanoparticles have been investigated. However, most of the present day nano based delivery systems pose a conundrum with respect to their complex synthesis procedures, poor in vivo stability and toxicity issues. Peptides due to their high biocompatibility could act as excellent materials for the synthesis of nanoparticulate drug delivery systems. Here, we have investigated dehydrophenylalanine (ΔPhe) di-peptide based self-assembled nanoparticles for the efficient delivery of Ccm as an antimalarial agent. The self-assembly and curcumin loading capacity of different ΔPhe dipeptides, phenylalanine–α,β-dehydrophenylalanine (FΔF), arginine-α,β-dehydrophenylalanine (RΔF), valine-α,β-dehydrophenylalanine (VΔF) and methonine-α,β-dehydrophenylalanine (MΔF) were investigated for achieving enhanced and effective delivery of the compound for potential anti-malarial therapy.ResultsFΔF, RΔF, VΔF and MΔF peptides formed different types of nanoparticles like nanotubes and nanovesicles under similar assembling conditions. Out of these, F∆F nanotubes showed maximum curcumin loading capacity of almost 68 % W/W. Ccm loaded F∆F nanotubes (Ccm-F∆F) showed comparatively higher (IC50, 3.0 µM) inhibition of Plasmodium falciparum (Indo strain) as compared to free Ccm (IC50, 13 µM). Ccm-F∆F nano formulation further demonstrated higher inhibition of parasite growth in malaria infected mice as compared to free Ccm. The dipeptide nanoparticles were highly biocompatible and didn’t show any toxic effect on mammalian cell lines and normal blood cells.ConclusionThis work provides a proof of principle of using highly biocompatible short peptide based nanoparticles for entrapment and in vivo delivery of Ccm leading to an enhancement in its efficacy as an antimalarial agent.

Durable, superoleophobic polymer-nanoparticle composite surfaces with re-entrant geometry via solvent-induced phase transformation.

Superoleophobic plastic surfaces are useful in a wide variety of applications including anti-fouling, self-cleaning, anti-smudge, and low-drag. Existing examples of superoleophobic surfaces typically rely on poorly adhered coatings or delicate surface structures, resulting in poor mechanical durability. Here, we report a facile method for creating re-entrant geometries desirable for superoleophobicity via entrapment of nanoparticles in polycarbonate surfaces. Nanoparticle incorporation occurs during solvent-induced swelling and subsequent crystallization of the polymer surface. The resulting surface was found to comprise of re-entrant structures, a result of the nanoparticle agglomerates acting as nucleation points for polymer crystallization. Examples of such surfaces were further functionalized with fluorosilane to result in a durable, super-repellent surface. This method of impregnating nanoparticles into polymer surfaces could prove useful in improving the anti-bacterial, mechanical, and liquid-repellent properties of plastic devices.

Depositing α-mangostin nanoparticles to sebaceous gland area for acne treatment

Although entrapment of nanoparticles of appropriate sizes at hair follicles has been clarified, there is no report on specific clinical application of this finding. Since sebaceous gland is associated with hair follicle, we hypothesize that effective acne vulgaris treatment/prevention can be achieved by depositing anti-acne agent in nanoparticle form at the hair follicles. Challenge of this strategy, however, lies at the finding of effective anti-acne particles with minimal skin irritation. Here using cellulose-based nanoparticles as nano-reservoir and α-mangostin (an active component isolated from the edible Garcinia mangostana Linn. fruit) as anti-acne agent, we prepare nanoparticles highly loaded with α-mangostin. Ability of the obtained particles to sustained release α-mangostin into synthetic sebum is demonstrated. The obtained mangostin particles are verified for their insignificant skin irritation through the two-week, twice-daily open application test in 20 healthy human volunteers. Excellent entrapment and sustainment of the mangostin nanoparticles at the hair follicles are elucidated in six human volunteers by detecting the presence of α-mangostin at the roots of hairs pulled from the treated skin area. The 4-week-randomized, double-blind, placebo-controlled, split-face study in 10 acne patients indicates significant improvement in acne vulgaris condition on the side twice daily applied with mangostin nanoparticles.

Preparation and in vitro investigation of antigastric cancer activities of carvacrol‐loaded human serum albumin nanoparticles

In this study, carvacrol-loaded human serum albumin (HSA) nanoparticles were developed and characterised. Nanoparticles were prepared by desolvation and emulsion/desolvation methods. Encapsulation efficiency (EE%) and loading capacity (LC%) of nanoparticles prepared by desolvation method were 48.4 and 45.1%, respectively. Carvacrol-loaded nanoparticles had 132±42 nm in diameter with monomodal distribution. Carvacrol-loaded nanoparticles which is prepared by emulsion/desolvation method had EE% and LC% of 32 and 32.3%, respectively, and 230±38 nm in size. The release of carvacrol from nanoparticles was monitored in phosphate-buffered saline (pH=7.4), 100 rpm at 37°C for 10 days. About 21.4% of carvacrol was released after 3 h from nanoparticles that were prepared by desolvation method. In emulsion/desolvation method, 26.8% of total carvacrol was released during 3 h of incubation. Cytotoxicity effect of loaded carvacrol was assessed by 3-[4, 5 dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) test on gastric cancer cells line (AGS). Cell line was exposed to the free carvacrol, unloaded and carvacrol-loaded nanoparticles for 48 h. The half maximal inhibitory concentration (IC50) for free carvacrol, unloaded and carvacrol-loaded HSA nanoparticles were 30, 1070 and 120 µg/ml, respectively. In conclusion, the results of this study showed applications of HSA nanoparticles for entrapment of carvacrol and antigastric cancer activity. Moreover, loading of carvacrol in combination with chemotherapy agents into the HSA nanoparticles may treat cancer cells better than single drug loaded nanoparticles.

Stability-Inspired Entrapment of Ag Nanoparticles in ZrO2 Thin films

Shape and size consistency of Ag nanoparticles is a challenging aspect when practical plasmonic devices are to be developed for their surface-specific activities. This study presents a simple chemical synthesis process which enables effective and rather uniform entrapment of Ag nanoparticles in dielectric oxide matrix at room temperature, without any assistance of physical/chemical agents. Uniformly distributed citrates capped Ag nanoparticles were preformed with a modified “Turkevich” approach and subsequently entrapped in mesoporous ZrO2 thin films. On the basis of transmission electron microscopy and photoelectron spectroscopy, results, size, shape, and chemical states of Ag nanoparticles were studied and correlated to the plasmonic properties of nanocomposite film formed by such entrapped nanoparticles. Plasmonic stability of these nanoparticles was confirmed in comparison of their dispersion on glass, and explained using extended Mie scattering theory.

Reduction of Nitrate in Groundwater by Fe(0)/Magnetite Nanoparticles Entrapped in Ca-Alginate Beads

Calcium alginate beads entrapping a mixture of Fe(0) and nanosized magnetite (NMT) were prepared and evaluated for their capability to reduce nitrate in groundwater. Microscopic and spectroscopic analyses of the beads revealed that clusters of Fe(0)/NMT were entirely embedded in alginate polymer matrix containing a large number of carboxylic and hydroxyl functional groups. The extent of nitrate reduction increased with increasing content of Fe(0) and NMT in the beads, but there was a critical NMT mass limit relative to Fe(0) mass where no further increase in nitrate reduction occurred. The beads showed slower nitrate reduction kinetics than bare Fe(0)/NMT but had comparable capacity in overall nitrate removal. Nitrate reduction increased proportionally with an increase in bead dosage to give a maximum removal of 94.5 % at 37.5 g L−1 in 48 h. Nitrate reduction with 50 g L−1 beads achieved completion of two reduction cycles in 72 h to reduce 2.19 mM nitrate to less than 0.71 mM (10 mg-N L−1) in each cycle. The overall results demonstrated that the beads developed in this study have a potential utility in remediation of nitrate in groundwater.

Evaluation of iron oxide nanoparticle micelles for magnetic particle imaging (MPI) of thrombosis.

Magnetic particle imaging (MPI) is an emerging medical imaging modality that directly visualizes magnetic particles in a hot-spot like fashion. We recently developed an iron oxide nanoparticle-micelle (ION-Micelle) platform that allows highly sensitive MPI. The goal of this study was to assess the potential of the ION-Micelles for MPI-based detection of thrombi. To this aim, an in vivo carotid artery thrombosis mouse model was employed and ex vivo magnetic particle spectrometer (MPS) measurements of the carotid arteries were performed. In addition, we studied the effect of functionalization of the ION-Micelle nanoplatform with fibrin-binding peptides (FibPeps) with respect to nanoparticle thrombus uptake and hence thrombus detection. In vivo quantitative MR imaging pre- and post-ION-Micelle injection was performed as reference for visualization of ION-micelle uptake. ION-Micelles significantly decreased T2 values in the thrombi with respect to pre-injection T2 values (p < 0.01) and significantly increased ex vivo MPS thrombus signal with respect to the noninjured, contralateral carotid (p < 0.01). Functionalization of the ION-Micelles with the FibPep peptides did not result in an increased MPS thrombus signal with respect to the non-fibrin binding ION-Micelles. The lack of a significant increased thrombus uptake for the FibPep-ION-Micelles indicates that (non-fibrin-specific) entrapment of nanoparticles in the mesh-like thrombi is the key contributor to thrombus nanoparticle uptake. Therefore, (nontargeted) ION-Micelles might be of value for noninvasive MPI-based diagnosis, characterization and treatment monitoring of thrombosis.

Cellular uptake, antioxidant and antiproliferative activity of entrapped α-tocopherol and γ-tocotrienol in poly (lactic-co-glycolic) acid (PLGA) and chitosan covered PLGA nanoparticles (PLGA-Chi)

The aim of this study was to formulate and characterize α-tocopherol (α-T) and tocotrienol-rich fraction (TRF) entrapped in poly (lactide-co-glycolide) (PLGA) and chitosan covered PLGA (PLGA-Chi) based nanoparticles. The resultant nanoparticles were characterized and the effect of nanoparticles entrapment on the cellular uptake, antioxidant, and antiproliferative activity of α-T and TRF were tested. In vitro uptake studies in Caco2 cells showed that PLGA and PLGA-Chi nanoparticles displayed a greater enhancement in the cellular uptake of α-T and TRF when compared with the control without causing toxicity to the cells (p<0.0001). Furthermore, the cellular internalization of both PLGA and PLGA-Chi nanoparticles labeled with FITC was investigated by fluorescence microscopy; both types of nanoparticles were able to get internalized into the cells with reasonable amounts. However, PLGA-Chi nanoparticles showed significantly higher (3.5-fold) cellular uptake compared to PLGA nanoparticles. The antioxidant activity studies demonstrated that entrapment of α-T and TRF in PLGA and PLGA-Chi nanoparticles exhibited greater ability in inhibiting cholesterol oxidation at 48h compared to the control. In vitro antiproliferative studies confirmed marked cytotoxicity of TRF on MCF-7 and MDA-MB-231 cell lines when delivered by PLGA and PLGA-Chi nanoparticles after 48h incubation compared to control. In summary, PLGA and PLGA-Chi nanoparticles may be considered as an attractive and promising approach to enhance the bioavailability and activity of poorly water soluble compounds such as α-tocopherol and tocotrienols.

Hybrid nanocomposite from aniline and CeO2 nanoparticles: Surface protective performance on mild steel in acidic environment

This present work contributes to the development of a new generation of active corrosion inhibitors composed of CeO2 nanoparticles covered with polyaniline that are able to release entrapped nanoparticles in acidic medium. Nanocomposites of aniline and CeO2 nanoparticles have been chemically synthesized by in-situ polymerization. The structural evolutions and morphological characteristics of PANI/CeO2 nanocomposite (PCN) have performed using various techniques such as XRD, IR, XPS, SEM and TEM analysis. It was illustrated from SEM and TEM observation that the PCN has globular particle with core–shell structure. The inhibition properties of synthesized PCN on mild steel (MS) corrosion in 0.5M HCl were estimated using weight loss and electrochemical techniques. Potentiodynamic polarization results revealed PCN to be a mixed-type inhibitor, while impedance results indicate the adsorption of the PCN film on the MS surface. The inhibition efficiency of PCN was found to increase almost linearly with concentration. Moreover, an increase in the water contact-angle with PCN indicated its adsorption at the MS surface, and ATR-IR, SEM/EDAX and AFM visualization confirmed the formation of a protective film adsorbed on a MS surface. Finally, it was concluded that the PCN is a potential inhibitor for mild steel in HCl medium.

Curcumin entrapped folic acid conjugated PLGA–PEG nanoparticles exhibit enhanced anticancer activity by site specific delivery

Herein we report curcumin entrapped nanoparticles of PLGA–PEG copolymer which were conjugated with folic acid (PPF copolymer) for site specific targeting since many cancer cells exhibit external folic acid binding receptors.

Fabrication of DNA, o-phenylenediamine, and gold nanoparticle bioimprinted polymer electrochemical sensor for the determination of dopamine

A simple methodology was used to develop a novel molecularly bioimprinted polymer (MBIP) sensor for the determination of dopamine. The bioimprinted film was prepared by electrochemical entrapment of ds-DNA and Au nanoparticles in the o-phenylenediamine network via one-step electropolymerization on the surface of the modified pencil graphite electrode. The integration of ds-DNA with molecularly imprinted polymer sensors allowed the preparation of novel analytical tools with more selectivity for the determination of dopamine in complex matrices. The fabrication process of the proposed MBIP sensor was evaluated by atomic force microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The proposed sensor showed good selectivity for dopamine, compared to the conventional electrochemical methods and the chemicals with high similarity to dopamine. Also, it had a comparable sensitivity, stability, repeatability and reproducibility. Differential pulse voltammetry was applied as a sensitive analytical method for the determination of dopamine and a good linear relationship between dopamine concentration and peak current was obtained within the range of 20–7000nM with a detection limit of 6nM. Furthermore, it was successfully applied for determination of dopamine in biological samples.

In Vitro Efficacy of Polysaccharide-Based Nanoparticles Containing Disease-Modifying Antirheumatic Drugs

To evaluate the therapeutic efficacy of dexamethasone (DM) and methotrexate (MTX) entrapped within polysialic acid (PSA)-trimethyl chitosan (TMC) nanoparticles using an in vitro model of rheumatoid arthritis (RA). The loading capacity of the PSA-TMC nanoparticles was determined. An RA in vitro model was developed by stimulating a synovial cell line with a proinflammatory mediator. Multiplex immunoassay was used to determine changes in the secretion of interleukin-6 (IL-6), interleukin-8 (IL-8), and granulocyte-macrophage colony-stimulating factor (GM-CSF) by the in vitro model following administration of the DM- and MTX-loaded nanoparticles. The loading capacity of the PSA-TMC nanoparticles was approximately 0.1mg of drug/mg of nanoparticle. When applied to our in vitro model of RA, there were no significant differences in the concentrations of IL-6 and IL-8 when comparing the free drugs and drug-loaded nanoparticles, administered at concentration of 0.1mg/ml and 1.0mg/ml, respectively. The present study verified that MTX and DM are able to retain bioactivity when loaded into PSA-TMC nanoparticles. Although in vitro efficacy was not increased, the in vivo efficacy will likely be enhanced by the site-specific targeting conferred by nanoparticle entrapment.

Folate-decorated PEG–PLGA nanoparticles with silica shells for capecitabine controlled and targeted delivery

Di-block polymer of poly (lactic-co-glycolic acid)-poly (ethylene glycol) (PLGA-PEG) end-capped with capecitabine (CAP) at the hydrophobic domain and folate (FA) at hydrophilic domain were synthesized respectively. The products were extensively studied by nuclear magnetic resonance ((1)H NMR) and gel permeation chromatography (GPC) measurement. By using emulsion-solvent evaporation method, the two conjugates, drug CAP and tetramethoxysilane (TMOS) were mixed to form the CAP entrapped nanoparticles (NPs) with the FA moieties exposed on NPs surface, while simultaneously forming a cross-linked silica shell out of hydrophobic PLGA core domain. The testing results showed the CAP-loaded NPs presented suitable physical stability, favorable size around 200 nm, negative zeta potential charge (-28.43 ± 2.55 mV) and high encapsulation efficiency (69%). Both silica shell cross-linked drug-loaded NPs (SSCL NPs) and none silica shell cross-linked NPs (NSSCL NPs) provided an initial burst release and followed by a sustained two-stage release of the CAP. Straight lines approximate the steady-state for the two-stage release, and the K/K' of the two stages are 1.96304 and 1.78697 respectively suggesting the silica shell influenced the release of first stage significantly.

Surface chemistry and entrapment of magnesium nanoparticles into polymeric micelles: a highly biocompatible tool for photothermal therapy.

A novel highly biocompatible nanosystem containing Mg nanoparticles is reported, characterized and tested as a suitable and non-toxic tool for photothermal therapy.

Facile synthesis of highly stable heterogeneous catalysts by entrapping metal nanoparticles within mesoporous carbon

Cycling instability is a persisting problem in heterogeneous catalysis. Here we report an efficient strategy to enhance the recyclability of the heterogeneous catalysts by in situ entrapment of active nanoparticles in mesoporous carbon. A hard template method was used to fabricate the desired catalyst, where Al2O3 was employed as the template and polyphenols were used as carbon source as well as the stabilizing agent. Based on N2 adsorption/desorption analysis, the catalysts adopt the high surface area of the Al2O3 template and feature mesoporous pores. Additionally, the noble metal nanoparticles (Pd) were found to be well entrapped inside the carbon matrix with good dispersion. The as-prepared catalysts were highly active in various heterogeneous hydrogenations of CC containing substrates (quinoline, cinnamaldehyde, etc.) and exhibited excellent cycling stability without any significant loss of activity for 10 recycles, which is superior to that of the commercial Pd/C catalyst.

Effective Hydrogenation of p-Chloronitrobenzene over Iridium Nanoparticles Entrapped in Aluminum Oxy-Hydroxide under Mild Conditions

The Ir/AlO(OH) catalyst was prepared by sol-gel method and used for selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroniamine (p-CAN). The mechanism of p-CNB hydrogenation over the catalyst was discussed. The hydrogen bond between the surface hydroxyl groups of the catalyst and the nitrogen present in p-CNB facilitated the hydrogenation of nitro group. On the other hand, the formation of hydrogen bond between the hydrogenation product and water promotes the rapid desorption of the hydrogenation product on the surface of the catalyst. Thus the activity and selectivity were greatly promoted.

Nanoparticle-Filled Complex Colloidosomes for Tunable Cargo Release

Capsules with a shell made out of nanoparticles, so-called colloidosomes, are very interesting for controlled encapsulation and release because of their selectively permeable shell, their mechanical stability, and the possibility to make them from many materials. Here, we report the creation of complex colloidosomes that can release encapsulated cargo on-demand in single or multiple release events. Unprecedented on-demand, multiple release is achieved by incorporating functional nanoparticles within the colloidosome hollow core. The entrapped nanoparticles enable pH-triggered release by either swelling to rupture the capsule shell in one single event or desorbing on-demand cargo molecules initially adsorbed on their surface. Implementation of such mechanisms in capsules with magnetically responsive shells enabled the creation of colloidosomes exhibiting unique spatiotemporal control of cargo release.

Biodegradable sodium alginate‐based semi‐interpenetrating polymer network hydrogels for antibacterial application

A series of biodegradable, semi-interpenetrating polymer network (semi-IPN) hydrogels were synthesized from a combination of carbohydrate polymer and sodium alginate (NaAlg) with acrylamide and dimethyl aminoethyl methacrylate, and crosslinked with N,N-methylenebisacrylamide via radical redox polymerization. The cytocompatibility of the hydrogels with respect to their monomers and semi-IPN hydrogels was evaluated in vitro using cultures of mouse fibroblast cell lines. This study allowed the entrapment of silver nanoparticles (NPs) into semi-IPN hydrogel networks by the in situ reduction of Ag(+) ions using NaBH4 as a reducing agent. UV-visible spectroscopy confirmed the formation of silver NPs in the semi-IPN hydrogel matrix. The formation of silver NPs was also confirmed from a themogravimetric analysis weight loss difference between hydrogel and silver nanocomposite as 32%. The morphology and structure of the AgNPs present in the hydrogel networks were examined by scanning electron microscopy. Transmission electron microscopy revealed silver NPs with a size of ∼5 nm. The silver nanocomposite hydrogel exhibited good antibacterial activity against both gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria. These results suggest that the hydrogel can be applied as wound dressings and for water purification purposes.