Z-average Hydrodynamic Diameter Research Articles

Comparison of atomic force microscopy and dynamic light scattering on the size characterization of surfactant-modified WC/Co nanoparticles dispersed in aqueous media

Tungsten carbide cobalt nanoparticles (WC/Co NPs) are extensively employed to fabricate wear-resistant parts, cutting tools, and rock drills. The colloidal stability of the WC/Co NP suspension plays a vital role in determining the mechanical properties of WC/Co-based products. In this work, dispersion of WC/Co NPs in aqueous media was conducted using surfactants (cationic, anionic, nonionic) with different concentration conditions. The z-average hydrodynamic diameters measured using dynamic light scattering (DLS) revealed the optimal surfactant for WC/Co NP dispersion: cationic hexadecyltrimethylammonium bromide (CTAB) which induces interparticle electrostatic repulsion forces at a concentration of 2 g/L. The capping behavior of CTAB was demonstrated using Zeta-potential analysis, Fourier transform infrared spectroscopy, and X-ray diffraction measurements. The mean size measurement of immobilized WC/Co NPs was also conducted using atomic force microscopy (AFM). We demonstrate a comparative protocol between number-weighted mean sizes measured using AFM (dAFM) and DLS (dDLS) in relation to the relative standard deviation (RSD) from AFM measurements. A highly linear correlation was demonstrated between dDLS/dAFM and RSD. We indicate that for polydisperse (RSD > 0.1) and non-spherical NPs, the highest correlation between dDLS and dAFM exists when the RSD is 0.37, where dDLS/dAFM is close to 1.

Derivatized chitosan-oil-in-water nanocapsules for trans-cinnamaldehyde delivery

trans-Cinnamaldehyde, known for its bacterial anti-quorum sensing activity when applied at sublethal concentrations, has gained traction given its potential use against multidrug resistant bacteria. In this work, trans-cinnamaldehyde-loaded oil-in-water nanocapsules coated with chitosan, N,N,N-trimethyl chitosan chloride, N-(2-(N,N,N-trimethylammoniumyl)acetyl) chitosan chloride or N-(6-(N,N,N-trimethylammoniumyl)hexanoyl)chitosan chloride were obtained. All the formulated nanocapsules showed a Z-average hydrodynamic diameter ~ 160 nm and ζ-potential higher than +40 mV. N,N,N-trimethyl chitosan-coated oil-in-water nanocapsules showed the greatest trans-cinnamaldehyde association efficiency (99.3 ± 7.6) % and total payload release (88.6 ± 22.5) %, while N-(6-(N,N,N-trimethylammoniumyl)hexanoyl)chitosan chloride chitosan-coated oil-in-water nanocapsules were the only formulations stable in phosphate buffer saline PBS (pH 7.4) upon incubation at 37 °C for 24 h. Future work should address the stability of the developed nanocapsules in culture media and their biological performance.

Remediation of Pear Iron Deficiency Chlorosis by Nanocellulose-iron Chelation and the Underlying Mechanism

Nanocrystal cellulose possesses a strong capability to chelate Fe due to its adsorptive properties. Iron deficiency chlorosis (IDC) is a mineral disorder that remarkably weakens pear photosynthesis, causing declines in plant yields and quality. Conventional methods for controlling IDC generally lack efficiency and overuse chemicals. Foliar application of nanocellulose (NC)-Fe chelate (NCFe) provides a new approach to remediate IDC in pear (Pyrus betulifolia). In this study, NC was prepared by acidic hydrolysis using 64 wt% H2SO4 at 45 °C for 45 minutes. NCFe was formulated based on the net charge density of NC and ferrous sulfate (FeSO4) solution. The nanoparticle properties were characterized by transmission electron microscopy (TEM), dynamic light scattering, and conductometry. Pyrus betulifolia seedlings were pre-etiolated in an improved Hoagland’s nutrient solution and treated with bicarbonate. Changes in chlorophyll content, active Fe content, and photosynthesis rate in NCFe-treated leaves were determined by SPAD values, spectrophotometry, and photosynthetic apparatus, respectively. Ferritin genes (PbFER) and pectin methylesterase genes (PbPME) were extracted from leaf tissue, and gene expression profiles were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The results showed that NCFe particles maintained a whisker-like morphology; the Z-average hydrodynamic diameter and zeta potential of NCFe measured by dynamic light scattering were 107.4 ± 3.0 nm and −9.7 ± 0.4 mV, respectively. When NCFe was prepared at a mixing ratio of 1:3000, the total chlorophyll content, active Fe content, and net photosynthetic rate of plant leaves were significantly enhanced by 23.8%, 65.9%, and 40.4% after 72 hours of treatment, respectively, compared with FeSO4 spraying. Importantly, NCFe treatment also significantly downregulated the expression of PbPME and upregulated the expression of PbFER, which are key genes regulating the active Fe content.

Colloidal stability and aggregation kinetics of nanocrystal CdSe/ZnS quantum dots in aqueous systems: Effects of ionic strength, electrolyte type, and natural organic matter

Understanding the stability and aggregation of nanoparticles in aqueous milieu is critical for assessing their behavior in the natural and engineered environmental systems and establishing their threat to human and ecosystems health. In this study, the colloidal stability and aggregation kinetics of nanocrystal quantum dots (QDs) —CdSe/ZnS QDs—were thoroughly explored under a wide range of aqueous environmental conditions. The z-average hydrodynamic diameters (z-avg. HDs) and zeta potential (ξ potential) of CdSe/ZnS QDs were measured in monovalent electrolyte (NaCl) and divalent electrolyte (CaCl2) solutions in both the absence and presence of natural organic matter (NOM)—Suwannee River natural organic matter, SRNOM to assess the dynamic growth of these nanoaggregate-QD-complexes, and the evaluation of their colloidal stability. Results show that CaCl2 was more effective to destabilize the QDs compared to NaCl at similar concentrations. An increase in NaCl concentration from 0.01 to 3.5 M increased the z-avg. HD of QD aggregates from 61.4 nm to 107.2 nm. The aggregation rates of QDs increased from 0.007 to 0.042 nm·s−1 with an increase in ionic strength from 0.5 to 3.5 M NaCl solutions, respectively. In the presence of Na+ cations, the aggregation of QDs was limited as steric forces generated by the original surface coating of QDs prevailed. In the presence of CaCl2, the aggregation of QDs was observed at a low concentration of CaCl2 (0.0001 M) with a z-avg. HD of 74.2 nm that significantly increased when the CaCl2 was higher than 0.002 M. Larger sizes of QD aggregates were observed at each level of CaCl2 concentration in suspensions of 0.002–0.1 M, as the z-avg. HDs of QDs increased from 125.1 to 560.4 nm, respectively. In the case of CaCl2, an increase in aggregation rates occurred from 0.035 to 0.865 nm·s−1 with an increase in ionic strength from 0.0001 M to 0.004 M, respectively. With Ca2+ cations, the aggregation of QDs was enhanced due to the bridging effects from the formation of complexes between Ca2+ cations in solution and the carboxyl group located on the surface coating of QDs. In the presence of SRNOM, the aggregation of QDs was enhanced in both monovalent and divalent electrolyte solutions. The degree of aggregation formation between QDs through cation-NOM bridges was superior for Ca2+ cations compared to Na+ cations. The presence of SRNOM resulted in a small increase in the size of the QD aggregates for each of NaCl concentrations tested (i.e., 0.01 to 3.5 M, except 0.1 M), and induced a monodispersed and narrower size distribution of QDs suspended in the monovalent electrolyte NaCl concentrations. In the presence of SRNOM, the aggregation rates of QDs increased from 0.01 to 0.024 nm 1 with the increase of NaCl concentrations from 0.01 to 2 M, respectively. The presence of SRNOM in QDs suspended in divalent electrolyte CaCl2 solutions enhanced the aggregation of QDs, resulting in the increase of z-avg. HDs of QDs by approximately 19.3%, 42.1%, 13.8%, 1.5%, and 24.8%, at CaCl2 concentrations of 0.002, 0.003, 0.005, 0.01, and 0.1 M, respectively. In the case of CaCl2, an increase in aggregation rates occurred from 0.035 to 0.865 nm·s−1 with an increase in ionic strength from 0.0001 to 0.004 M, respectively. Our findings demonstrated the colloidal stability of QDs and cations-NOM-QD nanoparticle complexes under a broad spectrum of conditions encountered in the natural and engineered environment, indicating and the potential risks from these nanoparticles in terms of human and ecosystem health.

Preparation and characterization of soybean protein isolate-dextran conjugate-based nanogels

Soybean protein isolate (SPI)-dextran conjugate-based nanogels were prepared via the Maillard reaction combined with protein self-assembly in this study. The dextran molecular weight (40 kDa), SPI/dextran mass ratio (1:1.75), and incubation time (3.3 d) for preparing SPI-dextran conjugate (SDC) were firstly optimized. The SDC was confirmed by analyzing the changes in protein composition and infrared absorption bands and showed loosened tertiary conformation, reduced surface hydrophobicity, decreased Z-average hydrodynamic diameter (Dh) and zeta potential, and improved emulsifying properties compared to the native SPI. Effects of conjugate concentration, pH, heating temperature, and time on Dh and polydispersity index were also evaluated. The SDC-based nanogels were translucent in aqueous solution and exhibited a spherical core-shell structure with a Dh of ∼104.4 nm and a good stability against thermal treatment, ionic strength, and storage. Results demonstrated the SDC-based nanogels possessed a potential to be used as desirable nanocarriers for encapsulating hydrophobic bioactive compounds.

A new procedure to quantify silver nanoparticles in sediments

Silver nanoparticles (AgNPs) are highly produced in developed countries for a variety of products. Consequently, AgNPs end up being introduced in aquatic systems all over the world, and usually deposited in riverine sediments, from where they can be taken up by aquatic organisms and transferred along the food chain. The analysis of AgNPs in natural samples is not an easy task, because of their low presence and complicated reactions, which can change their speciation. The objective of this work is to help in this challenge, developing a method applicable to analyse sediment samples from any place around the world where AgNPs are suspected to be present.Firstly, four methods for the synthesis of AgNPs were investigated by Ultraviolet–visible (UV–VIS) spectroscopy and particle size analysis. The methods differed in the reducing agent used and in the concentration of the stabilising agent applied. The method including NaBH4 and SDS (sodium dodecyl sulphate) resulted to be more adequate as the Surface Plasmon Resonance (SPR) band position and width indicated. This conclusion was corroborated considering the hydrodynamic diameters and polydispersity indices of the synthesised AgNPs. The Z-average hydrodynamic diameter and the UV–VIS spectrum of AgNPs synthesised using this method indicated that the AgNPs remained kinetically stable for at least 10 days.Finally, ten potential extraction solutions were investigated, in terms of maximal extraction efficiency, but minimal effects on AgNP dissolution and aggregation. The candidate solutions ranged from deionized water and salts to strong acids and bases. The intensity of the SPR band concluded that using NaOH media the synthesised AgNPs was kinetically stable. Moreover, TEM (Transmission Electron Microscopy) images showed that the AgNPs in NaOH retained their shape and size after 10 days. Therefore, NaOH media turned out to be the best potential extractant for the analysis of sediment samples.

Effect of pH and surfactants on the electrokinetic properties of nanoparticles dispersions and their application to the PET fibres modification

This paper presents the effect of surfactants, pH and electrolyte (0.1 × 10−3 M KCl) on the stability of the aqueous dispersions of commercial ZnO and AgCu nanoparticles. As the surfactants cationic hexadecyltrimethylammonium bromide (CTAB), anionic sodium dodecyl sulfate (SDS), and nonionic 4-(1,1,3,3-tetramethylbutyl)phenyl polyethylene glycol (Triton X-100) at concentrations of 0.5 × 10−3, 1.0 × 10−3, and 0.1 × 10−3 M, respectively, were used. The zeta potential values, z-average hydrodynamic diameter and long-term stability of ZnO and AgCu nanoparticles were examined by means of the dynamic light scattering (DLS) technique. It was found that the presence of ionic surfactants reduced the tendency of nanoparticles for agglomeration/aggregation and improved their colloidal stability. They were characterized by high (>|70| mV) and pH-independent zeta potential values. In addition, ZnO nanoparticles in the presence of ionic surfactants showed a better long-term stability than AgCu nanoparticles. Their z-average hydrodynamic diameters in CTAB and SDS were 195 ± 2 nm and 295 ± 5 nm, respectively, and remained almost unchanged for 5 days. The addition of KCl improved the stability of aqueous and containing nonionic surfactant dispersions of nanoparticles, what was reflected in the zeta potential values > 30 mV in almost the entire pH range. The stability of nanoparticles dispersion significantly affects the uniformity of nanoparticles distribution on the fibres surface. The uniformity of distribution of the ZnO and AgCu dispersion on the surface of polyester (PET) fibres was carried out by means of microscopic methods (SEM/EDS).

Curcumin, casein and soy polysaccharide ternary complex nanoparticles for enhanced dispersibility, stability and oral bioavailability of curcumin

Curcumin, casein and soy soluble polysaccharide ternary complex nanoparticles were produced in the water phase using alkaline dissolution, acidification and high-pressure homogenization. FTIR spectra showed that hydrogen bonding, hydrophobic and electrostatic interactions led to the formation of the nanoparticles. The nanoparticles had strong curcumin solubilizing power. The curcumin concentrations in the nanoparticle dispersions were 2.5–20 mg/mL, the curcumin loading efficiencies were ~97%, and the highest curcumin loading content was 48.6%. The nanoparticles had z-average hydrodynamic diameters of ~3.6 × 102 nm, and good physical stability and curcumin chemical stability after 30 days of storage at 25 °C. Due to the polysaccharide surfaces, the nanoparticles were dispersible in acidic and neutral solutions as well as re-dispersible in water after lyophilization. About 52.3% of the curcumin was released after 2 h digestion in simulated gastric fluid followed by 2 h digestion in simulated intestinal fluid. After oral administration in mice, the nanoparticle treatment group increased the curcumin oral bioavailability by 3.4-fold compared with the curcumin/Tween 20 group. This study showed that the ternary complex nanoparticles were an effective system for curcumin loading, protection and oral delivery.

Impact of zinc oxide nanoparticles in aqueous environments: influence of concentrations, natural organic matter and ionic strength

In this study, UV-vis absorption, adsorption, z-average hydrodynamic diameter, zeta potential and DLVO interaction energy of engineered zinc oxide (ZnO) NP suspensions were investigated as a function of concentration of the NPs, ionic strength (IS) and natural organic matter (NOM). The results suggested that stability of ZnO NPs plays an important role on their mobility and determination of their resulting risks in aquatic ecosystems. Increasing stability of the ZnO NPs makes the NPs to be easily suspended and transported within the surface water. On the other hand, decreasing stability reduces the mobility of the NPs within the surface water due to aggregation, thereby blocking the NPs from reaching the water resources available for the production of drinking water and consequently reducing water contamination.

Large scale aggregation in magnetic colloids induced by high frequency magnetic fields

The paper presents evidence of large scale aggregation in an aqueous dispersion of magnetic microgels, induced by 100 kHz AC magnetic fields with amplitude ranging from 40 Oe to 120 Oe. The microgels with 250 nm z-average hydrodynamic diameter and 44 emu/g saturation magnetization are composed by 8 nm magnetite nanoparticles imbedded in (3-acrylamidopropyl)-trimethylammonium chloride (APTAC) matrix. The magnetically induced aggregation was investigated by means of light extinction (LE) and small angle light scattering (SALS) at room temperature. The SALS experiments show the formation and growth of field direction elongated aggregates with thickness in the range of a few microns and length in the range of tens to hundreds microns. The extinction experiments show the increasing of aggregate total volume with increasing magnetic field amplitude. It was estimated that, at the saturation of the aggregation process in 120 Oe amplitude field, the aggregates consist of about 80% of the total amount of magnetic microgels within the sample. These findings have potential interest for magnetic composite applications in magnetic hyperthermia and heat transfer applications.

Interfacial Structures of Droplet-Stabilized Emulsions Formed with Whey Protein Microgel Particles as Revealed by Small- and Ultra-Small-Angle Neutron Scattering.

Droplet-stabilized emulsions (DSEs) were made from oil droplets coated with whey protein microgel (WPM) particles. The WPM particles with z-average hydrodynamic diameters of 270.9 ± 4.7 and 293.8 ± 6.7 nm were obtained by heating whey proteins with 10 mM phosphate buffer, pH 5.9 (-PB) and no buffer (-NPB), respectively. The primary emulsions coated by WPM-NPB and WPM-PB particles had mass fractal dimensions of ∼2.75, as determined by small- and ultra-small-angle neutron scattering (SANS and USANS). The size of the subsequently formed DSEs (D32 ≈ 7-23 μm), which were stabilized by the primary emulsion droplets, made with either WPM-NPB (termed DSE-NPB) or WPM-PB (termed DSE-PB) was dependent on the concentration of the primary emulsion (10-60 wt %) in the aqueous phase. At the DSE-NPB interface, the adsorbed primary emulsion droplets formed a fractal network with a surface fractal dimension of about 3, indicating a rough interfacial layer. Combined SANS and USANS allowed a comprehensive understanding of the multilength scale structures from WPM particles to DSEs.

Aggregation and Stability of Iron Oxide and Alumina Nanoparticles: Influences of pH and Humic Acid Concentration

The scenario of released nanoparticles from consumer products into the environment especially natural waters has become a great concern nowadays. Assessing their aggregation and stability under environmental conditions is important in determining their fate and behavior in natural waters. The aggregation behavior of selected nanoparticles (iron oxide and alumina) was investigated at variable concentrations of humic acid (5, 10, 50 mg/L), and pH variation in solution. Dynamic light scattering was used to measure their z-average hydrodynamic diameter and zeta potential. Derjaguin-Landau-Verwey-Overbeak (DLVO) theory was used to explain the thermodynamic interactions between two particles. Then, the stability was evaluated by assessing their aggregation. The increasing of humic acid concentrations enhanced aggregation of iron oxide and alumina nanoparticles, particularly at low pH levels. The maximum aggregation was found in pH below the point of zero charge (PZC) due to electrostatic destabilization and electrostatic stabilization that took place at pH above the point of zero charge. Meanwhile, at pH point of zero charge, nanoparticles were coated with negative humic acid charged. From this study, properties of nanoparticles (size, surface charge, Hamaker constant) and environmental condition (humic acid concentration, pH) have their specific roles to control the fate and behavior of nanoparticles in environmental media.

Characterisation of nano-sized particles in chemical mechanical polishing wastewater

Treatment of chemical mechanical polishing (CMP) wastewater and fluoride-containing wastewater in semiconductor manufacturing are conventionally separated. The combined treatment of these two streams of wastewater was studied in terms of zeta potential and z-average hydrodynamic diameter profiles as a function of pH 2 to 12. Optimum pH for CMP wastewater was at pH 6 with zeta potential value of −10 mV and mean particle size of 180 d.nm. Meanwhile, for fluoride-containing wastewater the optimum pH obtained was at pH 9 with zeta potential of 10 mV and mean particle size of 5,214 d.nm. These two streams were combined together at their respective optimum pH and resulted a zeta potential value of 0.55 mV and mean particle size of 12,590 d.nm. Results indicated that the combined treatment for both polishing and fluoride-containing wastewater were beneficial as a larger flocs of fluorosilicate 26(SiF62−) was generated without the presence of coagulation chemicals. It is proposed that positively charged particles present in fluoride-containing wastewater become adsorbed on the surface of silica nanoparticles in CMP wastewater in which act as nuclei and enhances flocculation since repulsive force of both wastewater is decreased.

Rhizome of Anemarrhena asphodeloides as mediators of the eco-friendly synthesis of silver and gold spherical, face-centred cubic nanocrystals and its anti-migratory and cytotoxic potential in normal and cancer cell lines

The water extract of Anemarrhena asphodeloides, the traditional oriental medicinal plant, mediated the eco-friendly synthesis of silver nanoparticles (Aa-AgNPs) and gold nanoparticles (Aa-AuNPs). First, its therapeutic rhizome was powdered prior to water extraction and then silver, gold nanoparticles were synthesized. Aa-AgNPs and Aa-AuNPs were found to be spherical, face-centred cubic nanocrystals with a Z-average hydrodynamic diameter of 190 and 258 nm, respectively. In addition, proteins and aromatic biomolecules were the plausible players associated with the production and stabilization of Aa-AgNPs; instead, phenolic compounds were responsible for the synthesis and stability of Aa-AuNPs. In vitro cytotoxic analysis revealed that up to 50 μg.mL−1 concentration Aa-AuNPs did not exhibit any toxicity on 3T3-L1, HT29 and MCF7 cell lines, while being specifically cytotoxic to A549 cell line. On the contrary, Aa-AgNPs displayed a significantly higher toxicity in comparison to Aa-AuNPs in all cell lines specially MCF7 cell line. Since cancer cells were more sensitive to Aa-Au/AgNPs treatments, further evaluation was done in order to determine their anticancer potential. Reactive oxygen species (ROS) generation was not affected by Aa-AuNPs, on the other hand, Aa-AgNPs treatment exhibited a higher potential to induce oxidative stress in A549 cells than HT29 and MCF7 cells. In addition, Aa-Ag/AuNPs reduced cell migration in A549 cells at 10 and 50 μg.mL−1, respectively. So far, this is the only report uncovering the ability of A. asphodeloides to synthesize silver and gold nanoparticles with anticancer potential and also indirectly enabling its large-scale utilization with value addition.

Tumor-penetrating Peptide Conjugated and Doxorubicin Loaded T1-T2 Dual Mode MRI Contrast Agents Nanoparticles for Tumor Theranostics.

The conventional chemotherapeutics could not be traced in vivo and provide timely feedback on the clinical effectiveness of drugs.Methods: In this study, a tumor-penetrating peptide RGERPPR (RGE) modified, Gd-DTPA conjugated, and doxorubicin (DOX) loaded Fe3O4@SiO2@mSiO2 nanoparticle drug delivery system (Fe3O4@SiO2@mSiO2/DOX-(Gd-DTPA)-PEG-RGE NPs) was prepared for tumor theranostics.Results: The Fe3O4@SiO2@mSiO2/DOX-(Gd-DTPA)-PEG-RGE NPs showed a z-average hydrodynamic diameter of about 90 nm, and a pH-sensitive DOX release profile. The 3 T MRI results confirmed the relaxivity of the NPs (r1 = 6.13 mM-1S-1, r2 = 36.89 mM-1S-1). The in vitro cellular uptake and cytotoxicity assays on U87MG cells confirmed that the conjugation of RGERPPR played a significant role in increasing the cellular uptake and cytotoxicity of the NPs. The near-infrared fluorescence in vivo imaging results showed that the NPs could be significantly accumulated in the U87MG tumor tissue, which should result from the mediation of the tumor-penetrating peptide RGERPPR. The MRI results showed that the NPs offered a T1-T2 dual mode contrast imaging effect which would lead to a more precise diagnosis. Compared with unmodified NPs, the RGE-modified NPs showed significantly enhanced MR imaging signal in tumor tissue and antitumor effect, which should also be attributed to the tumor penetrating ability of RGERPPR peptide. Furthermore, the Hematoxylin and Eosin (H&E) staining and TUNEL assay proved that the NPs produced obvious cell apoptosis in tumor tissue.Conclusions: These results indicated that Fe3O4@SiO2@mSiO2/DOX-(Gd-DTPA)-PEG-RGE NPs are an effective targeted delivery system for tumor theranostics, and should have a potential value in the personalized treatment of tumor.

PCL-b-P(MMA-co-DMAEMA)2 new triblock copolymer for novel pH-sensitive nanocapsules intended for drug delivery to tumors

A novel poly(ε-caprolactone) (PCL) and poly [(methyl methacrylate)-co-(2-dimethylamino)ethyl methacrylate)2] block copolymer, PCL-b-P(MMA-co-DMAEMA)2, was synthesized using atom transfer radical polymerization to obtain pH-sensitive nanocapsules intended for drug delivery to solid tumors. The synthesis was performed using PCL:DMAEMA:MMA at two different molar proportions 0.2:10:1 and 0.7:33:1. Nanocapsules prepared using PCL-b-P(MMA-co-DMAEMA)2 proved sensitivity to pH, presenting z-average hydrodynamic diameters of 73 and 71nm at pH7.4, and 96 and 101nm at pH5.5, respectively, because of the decrease in the diffusion coefficient of the nanocapsules due to the increase in amine protonation forming ammonium at the surface. Zeta potential at pH7.2 was +23mV for batch 1 and +13mV for batch 2. In vitro cytotoxicity of the materials (solutions) and the nanocapsules (dispersed in water) was evaluated in a tumoral cell model (human breast adenocarcinoma cell line, MCF-7) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT). The homopolymers PDMAEMA and PMMA showed low cytotoxicity up to 0.60 and 0.44mmolL−1, respectively. After applying the nanoformulation, the cell viability was not affected for copolymer concentrations up to 340mgL−1. The results showed the new triblock copolymer is a promising material to be used in novel nanocapsule formulations intended for drug delivery to solid tumors.

A facile, efficient and “green” route to pH-responsive crosslinked poly(methacrylic acid) nanoparticles

The synthesis of hydrophilic crosslinked poly(methacrylic acid) (PMAA) nanoparticles usually involves the use of organic solvents. In this study, a novel, facile and efficient route was developed for the “green” fabrication of PMAA nanoparticles in water. Crosslinked PMAA nanoparticles were prepared via simply copolymerizing MAA with crosslinker N,N′-methylenebisacrylamide in an aqueous solution of polyoxyethylene (20) sorbitan monolaurate (tween 20), sodium dodecylsulfate and 2,2′-azodiisobutyronitrile. The water-soluble PMAA chains produced in-situ are converted into water-insoluble PMAA/tween 20 complexes via hydrogen bonding interactions with tween 20. This leads to the homogenous nucleation and deposition growth of PMAA nanoparticles, thus realizing the fabrication of crosslinked PMAA nanoparticles in water. Crosslinked PMAA nanoparticles with a z-average hydrodynamic diameter in the range of 99–480nm and a normalized swelling ratio in the range of 1.3–3.1 were obtained by varying the reaction parameters. The pH-sensitivity, biocompatibility and carboxyl functional groups make the crosslinked PMAA nanoparticles ideal candidates for various biomedical applications.

An effective intracellular delivery system of monoclonal antibody for treatment of tumors: erythrocyte membrane-coated self-associated antibody nanoparticles

Antibody-based drugs have attracted much attention for their targeting ability, high efficacy and low toxicity. But it is difficult for those intrabodies, a kind of antibody whose targets are intracellular biomarkers, to become effective drugs due to the lack of intracellular delivery strategy and their short circulation time in blood. Human telomerase reverse transcriptase (hTERT), an important biomarker for tumors, is expressed only in cytoplasm instead of on cell membrane. In this study, the anti-hTERT blocking monoclonal antibody (mAb), as the model intrabody, was used to prepare nanoparticles (NPs), followed by the encapsulation of erythrocyte membrane (EM), to obtain the EM-coated anti-hTERT mAb NPs delivery system. The final NPs showed a z-average hydrodynamic diameter of about 197.3 nm. The in vitro cellular uptake by HeLa cells confirmed that compared with free anti-hTERT mAb, the EM-coated anti-hTERT mAb NPs exhibited a significantly increased uptake by tumor cells. Besides, the pharmacokinetic study confirmed that the EM encapsulation can remarkably prolong the circulation time and increase the area under curve (AUC) of NPs in blood. The EM-coated anti-hTERT mAb NPs exhibited a remarkably decreased uptake by macrophages than uncoated NPs, which may be responsible for the prolonged circulation time and increased AUC. Furthermore, the frozen section of tumor tissue was performed and proved that the EM-coated anti-hTERT mAb NPs can be more effectively accumulated in tumor tissues than the free mAb and uncoated NPs. In summary, this study indicated that EM-coated anti-hTERT mAb NPs are an effective delivery system for the long circulation and intracellular delivery of an intrabody, and make it possible for the intracellular biomarkers to become the potential targets of drugs.

Pleuropterus multiflorus (Hasuo) mediated straightforward eco-friendly synthesis of silver, gold nanoparticles and evaluation of their anti-cancer activity on A549 lung cancer cell line

Pleuropterus multiflorus (Hasuo) is a widely used medicinal plant in Korea and China for treating amnesia, isnomia, heart throbbing etc. With the constructive idea of promoting the wide-spread usage of P. multiflorus, we propose its indirect usage in the form of biologically active silver (Pm-AgNPs) and gold nanoparticles (Pm-AuNPs). The synthesized nanoparticles were predominantly spherical, crystalline with the Z-average hydrodynamic diameter of 274.8nm and 104.8nm respectively. Also, proteins and phenols were identified as the major players involved in their synthesis and stability. Further, Pm-AgNPs at 25μg/mL were significantly cytotoxic to lung cancer cells, whereas, Pm-AuNPs were not cytotoxic to both normal keratinocyte and lung cancer cells even at 100μg/mL. In addition, further evaluation of the anti-cancer activity of these new nanoparticles, such as migration and apoptosis, shown that Pm-AgNPs have a potential therapeutic effect on A549 lung cancer cell treatment. To the best of our knowledge, this is the first report dissecting out the ability of the endemic P. multiflorus for the synthesis of bioactive silver and gold nanoparticle which would open up doors for its extensive usage in medicinal field.

A Novel Gd-DTPA-conjugated Poly(L-\u03b3-glutamyl-glutamine)-paclitaxel Polymeric Delivery System for Tumor Theranostics

The conventional chemotherapeutics could not be traced in vivo and provide timely feedback on the clinical effectiveness of drugs. In this study, poly(L-γ-glutamyl-glutamine)-paclitaxel (PGG-PTX), as a model polymer, was chemically conjugated with Gd-DTPA (Gd-diethylenetriaminepentaacetic acid), a T1-contrast agent of MRI, to prepare a Gd-DTPA-conjugated PGG-PTX (PGG-PTX-DTPA-Gd) delivery system used for tumor theranostics. PGG-PTX-DTPA-Gd can be self-assembled to NPs in water with a z-average hydrodynamic diameter about 35.9 nm. The 3 T MRI results confirmed that the relaxivity of PGG-PTX-DTPA-Gd NPs (r1 = 18.98 mM−1S−1) was increased nearly 4.9 times compared with that of free Gd-DTPA (r1 = 3.87 mM−1S−1). The in vivo fluorescence imaging results showed that PGG-PTX-DTPA-Gd NPs could be accumulated in the tumor tissue of NCI-H460 lung cancer animal model by EPR effect, which was similar to PGG-PTX NPs. The MRI results showed that compared with free Gd-DTPA, PGG-PTX-DTPA-Gd NPs showed significantly enhanced and prolonged signal intensity in tumor tissue, which should be attributed to the increased relaxivity and tumor accumulation. PGG-PTX-DTPA-Gd NPs also showed effective antitumor effect in vivo. These results indicated that PGG-PTX-DTPA-Gd NPs are an effective delivery system for tumor theranostics, and should have a potential value in personalized treatment of tumor.