Quantum dots: synthesis, bioapplications, and toxicity

Ferrite nanoparticles of basic composition Ni_0.7-x Zn _x Cu_0.3Fe₂O₄ (0.0 ?? x ?? 0.2, x = 0.05) were synthesized through auto-combustion method and were characterized for structural properties using X-ray diffraction [XRD], scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy [FT-IR]. XRD analysis of the powder samples sintered at 600°C for 4 h showed the cubic spinel structure for ferrites with a narrow size distribution from 28 to 32 nm. FT-IR showed two absorption bands (v ₁ and v ₂) that are attributed to the stretching vibration of tetrahedral and octahedral sites. The effect of Zn doping on the electrical properties was studied using dielectric and impedance spectroscopy at room temperature. The dielectric parameters (??', ????, tan??, and ?? _ac) show their maximum value for 10% Zn doping. The dielectric constant and loss tangent decrease with increasing frequency of the applied field. The results are explained in the light of dielectric polarization which is similar to the conduction phenomenon. The complex impedance shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume. PACS: 75.50.Gg; 78.20; 77.22.Gm.     

Carbon nanotubes: properties,synthesis, purification,and medical applications

Current discoveries of different forms of carbon nanostructures have motivated research on their applications in various fields. They hold promise for applications in medicine, gene, and drug delivery areas. Many different production methods for carbon nanotubes (CNTs) have been introduced; functionalization, filling, doping, and chemical modification have been achieved, and characterization, separation, and manipulation of individual CNTs are now possible. Parameters such as structure, surface area, surface charge, size distribution, surface chemistry, and agglomeration state as well as purity of the samples have considerable impact on the reactivity of carbon nanotubes. Otherwise, the strength and flexibility of carbon nanotubes make them of potential use in controlling other nanoscale structures, which suggests they will have a significant role in nanotechnology engineering.     

Water soluble poly(ethylene glycol) prodrug of silybin: Design,synthesis, and characterization

Silybin, the main component of silymarin, is an antihepatotoxic agent. But it presents numerous challenges associated with its poor aqueous solubility which has been realized as the major problem in its dosage form development and clinical application. The objective of our study was to solubilize silybin by designing and synthesizing its aqueous soluble prodrug using high aqueous soluble polymeric carrier—poly(ethylene glycol) (PEG). A novel soluble silybin prodrug was synthesized with a linear PEG and succinic ester linkage, and was extensively characterized using proton NMR, FTIR, and TOF‐MS. Furthermore, the prodrug was evaluated for its drug loading capability which was 6.65% and the solubility was 800 mg/mL. The results indicate significantly higher solubility of the prodrug in comparison with silybin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Hole transport triphenylamine-spirosilabifluorene alternating copolymer: synthesis and optical, electrochemical and electroluminescent properties

A new copolymer, constituted by the regular alternation of a spirosilabifluorene with a triphenylamine moiety, P(TPA-SSBF), has been synthesized via Suzuki coupling reaction. The molecular, thermal, optical, electrochemical and electroluminescent properties have been characterized. The introduction of a spiro-structure in P(TPA-SSBF) leads to its high thermal stability and good solubility in common organic solvents. The alternating copolymer shows only an absorption peak of 342 nm, demonstrating that triphenylamine is significantly conjugated with fluorene rings in the polymer. P(TPA-SSBF) in chloroform solution and in solid state film exhibits blue emission peak at 423, 435 nm respectively. The electrochemical behaviors of the polymer were investigated by cyclic voltammetry. The reversible electrochemical oxidation and low ionization potential (5.47 eV) suggest that P(TPA-SSBF) might have potential application as hole transport material in polymer LEDs. The hole transport ability of P(TPA-SSBF) was verified by comparing the performance of the two types LED devices fabricated in this study.     

Radiation initiated synthesis,characterization, and swelling behavior of poly (acrylic acid-co-acrylamide)/starch grafted hydrogel

The powerful waves of ultrasound are used in polymerization reactions in the absence of initiator. In the present research, the hydrogel was obtained by water-soluble acrylic monomers, starch, and the crosslinking agent of methylene bis acrylamide dissolved in water/glycerol dual. The hydrogel is formed by these waves only in viscous environments such as glycerol, heat, or initiator is not required. In the presence of ultrasound, the time of product formation is reduced to a few minutes. Moreover, the resulting hydrogels have more uniform microscopic structure and are more swollen. The structure of the grafted hydrogel was examined meanwhile the hydrogel swelling in three environments of pure water, saltwater, and under pressure was measured. It was found that the grafted hydrogel has double swelling rate in the pure. Also, after loading the ciprofloxacin into the synthesized hydrogel, this drug is released 99% in initial 20 min. 0.1 g starch in 1.5 g acrylic hydrogel has the most drug release. The high swelling capacity in the pH ranges of 5–9 shows the extension of drug application in acidic or alkaline environments, and also after several using the gel and the capacity of water absorbency, which was about 70% of its initial water, indicates the perfect reusability capacity of the gel.     

Liposome: classification,preparation, and applications

Liposomes, sphere-shaped vesicles consisting of one or more phospholipid bilayers, were first described in the mid-60s. Today, they are a very useful reproduction, reagent, and tool in various scientific disciplines, including mathematics and theoretical physics, biophysics, chemistry, colloid science, biochemistry, and biology. Since then, liposomes have made their way to the market. Among several talented new drug delivery systems, liposomes characterize an advanced technology to deliver active molecules to the site of action, and at present, several formulations are in clinical use. Research on liposome technology has progressed from conventional vesicles to ‘second-generation liposomes’, in which long-circulating liposomes are obtained by modulating the lipid composition, size, and charge of the vesicle. Liposomes with modified surfaces have also been developed using several molecules, such as glycolipids or sialic acid. This paper summarizes exclusively scalable techniques and focuses on strengths, respectively, limitations in respect to industrial applicability and regulatory requirements concerning liposomal drug formulations based on FDA and EMEA documents.     

Simultaneous synthesis,stabilization, and self‐assembly of microscale drug particles in polymer films

The antisolvent synthesis of micrometer‐scale particles, their stabilization in suspension, and their subsequent self‐assembly as homogeneous polymer films suitable for drug delivery were studied. Ultrasonic agitation was used in the precipitation of the drug particulates, stabilization was carried out with hydroxypropyl methylcellulose (HPMC), and finally, drug‐encapsulated films containing HPMC and polyvinylpyrrolidone were synthesized. These contained as much 28% of the drug Griseofulvin, and the particles were distributed uniformly throughout the films. Most importantly, the redispersion of the drug‐loaded films in an aqueous matrix showed that the crystallinity remained unaltered, and there was no appreciable increase in the particle size distribution. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Novel biocompatible nanomaterial for biomedical application: Structural,morphological, magnetic,and in vivo toxicity investigations

Assessing the biocompatibility of magnetic nanoparticles for biomedical applications is highly demanded and attracted an increasing interest in the last years. We, herein report the synthesis, physical characterization, and biocompatibility of CoFe_(2-x-y-z)Gd_xSm_yHo_zO₄ (x = y = z = 0, 0.01) nanoparticles (NPs) synthesized by the auto-combustion method for the first time. The physicochemical and magnetic properties of the synthesized nanoparticles were fully characterized using various techniques including X-ray diffraction (XRD), Fourier transforms infrared spectra (FTIR), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). A single-phase with a space group Fd-3m and mixed spinel structure were confirmed by XRD, Rietveld analysis, and the cation distribution study. FTIR confirms the formation of the crystallographic sites of the spinel structure, namely the octahedral site and the tetrahedral site. The nanoparticles exhibited a quasi-spherical shape with size distribution (24–51 nm). VSM measurements reveal that magnetic properties can be tuned by doping for biomedical applications. To evaluate the safety of our nanoparticle sub-chronic toxicity was highlighted in Wistar rats by oral administration at doses of 500, 250,125, and 50 mg/kg and by intraperitoneal injection at doses of 40,20,10, and 5 mg/kg. Results showed no significant changes in the hematological parameters, serum biochemical system, organ weight, and histopathological examination (p > 0,05) for doses below 250 mg/kg and 40 mg/kg administered orally or by intraperitoneal injection respectively. The results of the current study suggesting that treatment with the nanoparticle for 28 days does not produce any significant toxicity in the male and female rats for the either using voices (oral, intraperitoneal) except at high doses. These findings reported here strongly suggest that the as-prepared nanoparticles can be used in several biomedical applications, including separation and purification, drug delivery, imaging (MRI contrast), and therapy (hyperthermia).     

Development and characterization of gelatin‐based hydrogels,emulsion hydrogels,and bigels: A comparative study

This study was designed to examine the physicochemical and electrical properties of gelatin‐based hydrogels, emulgels, and bigels. The chemical studies suggested an increase in hydrogen bonding in the emulgel and bigel when sesame oil (SO; representative vegetable oil) and SO organogel (OG; representative OG) were incorporated within the gelatin matrix. The emulgel and bigel showed better mechanical properties and higher electrical impedances compared to the hydrogel. The hydrogel showed similar swelling at pH 1.2 and 7.2. The swelling of the emulgel and bigel was higher at pH 7.2. The formulations were found to be highly hemocompatible; this indicated their biocompatible nature. Ciprofloxacin, a model antimicrobial drug, was incorporated within the formulations. The release of the drug was found to be diffusion‐mediated. The antimicrobial efficiency of all of the drug‐loaded formulations was found to be equivalent. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41502.     

Crystal structure,phase transition,vibrational spectra,and microwave dielectric characteristics of Ta5+ ionic substituted Co0.5Ti0.5NbO4 ceramics

In the present research, structural representation, phase transition, and dielectric characteristics of Ta⁵⁺ ionic substituted Co_0.5Ti_0.5(Nb_1-xTa_x)O₄ (x = 0–1) ceramics were thoroughly investigated. Combined with the changes of diffraction peaks in the X-ray diffraction spectra, such as (002) and (101) crystalline planes near 20°, and the evolutionary trend of the strongest peak in the Raman spectra, a phase transition from rutile to trirutile structure at x = 0.6 was confirmed, suggesting the emergence of structural evolution. Thus, the structural evolution showed a significant impact on the dielectric characteristics, as evidenced by the weakening of the dielectric polarizability with the increasing amount of Ta⁵⁺ ion, which led to a reduction in the dielectric constant; the dielectric loss is also closely related to the packing fraction (PF) arising from the structural changes. Additionally, infrared and THz time-domain spectroscopy revealed that the dielectric losses in the microwave band were originated from the oscillatory absorption of structural phonons and supported that the effects of structural evolution on the intrinsic dielectric properties due to the introduction of Ta⁵⁺ ion.     

Biomedical Polyurethanes for Anti-Cancer Drug Delivery Systems: A Brief,Comprehensive Review

With the intensive development of polymeric biomaterials in recent years, research using drug delivery systems (DDSs) has become an essential strategy for cancer therapy. Various DDSs are expected to have more advantages in anti-neoplastic effects, including easy preparation, high pharmacology efficiency, low toxicity, tumor-targeting ability, and high drug-controlled release. Polyurethanes (PUs) are a very important kind of polymers widely used in medicine, pharmacy, and biomaterial engineering. Biodegradable and non-biodegradable PUs are a significant group of these biomaterials. PUs can be synthesized by adequately selecting building blocks (a polyol, a di- or multi-isocyanate, and a chain extender) with suitable physicochemical and biological properties for applications in anti-cancer DDSs technology. Currently, there are few comprehensive reports on a summary of polyurethane DDSs (PU-DDSs) applied for tumor therapy. This study reviewed state-of-the-art PUs designed for anti-cancer PU-DDSs. We studied successful applications and prospects for further development of effective methods for obtaining PUs as biomaterials for oncology.     

Fenton and photo-Fenton degradation of 2-chlorophenol: Multivariate analysis and toxicity monitoring

The simultaneous occurrence of Fenton and photo-Fenton reactions is an attractive process for contamination remediation involving high toxicity and low biodegradability species. In this work, a multivariate experimental design was applied to the treatment of 2-chlorophenol, as representative of chlorinated aromatic compounds, in order to evaluate the use of the Fenton reagent under light irradiation (wavelength close to 400 nm for photo-Fenton reactions and up to 550 nm for Fenton-like reactions). Hence, the aim of this work is to study the evolution of toxicity through all the degradation process by characterizing the toxicity level of 2-chlorophenol and its reaction intermediates as a function of temperature and the Fenton reagent loads. Factorial experimental design was used to assign each variable's weight in TOC removal after 30 min of reaction. Hydrogen peroxide concentration appears as a main direct effect for a favorable TOC reduction. Temperature has also an important effect in the 2-chlorophenol degradation, especially when the ratio of Fenton reagents is not correctly chosen. More than 90% TOC reduction could be achieved in only 30 min of treatment. In addition, the HPLC analysis showed the elimination of the studied compound and its byproducts under specific working conditions. Finally, results indicated the importance of taking into account toxicity evolution.     

Beyond platinum: synthesis,characterization, and in vitro toxicity of Cu(II)-releasing polymer nanoparticles for potential use as a drug delivery vector

The field of drug delivery focuses primarily on delivering small organic molecules or DNA/RNA as therapeutics and has largely ignored the potential for delivering catalytically active transition metal ions and complexes. The delivery of a variety of transition metals has potential for inducing apoptosis in targeted cells. The chief aims of this work were the development of a suitable delivery vector for a prototypical transition metal, Cu²⁺, and demonstration of the ability to impact cancer cell viability via exposure to such a Cu-loaded vector. Carboxylate-functionalized nanoparticles were synthesized by free radical polymerization and were subsequently loaded with Cu²⁺ via binding to particle-bound carboxylate functional groups. Cu loading and release were characterized via ICP MS, EDX, XPS, and elemental analysis. Results demonstrated that Cu could be loaded in high weight percent (up to 16 wt.%) and that Cu was released from the particles in a pH-dependent manner. Metal release was a function of both pH and the presence of competing ligands. The toxicity of the particles was measured in HeLa cells where reductions in cell viability greater than 95% were observed at high Cu loading. The combined pH sensitivity and significant toxicity make this copper delivery vector an excellent candidate for the targeted killing of disease cells when combined with an effective cellular targeting strategy.     

LaF3 : Eu3+ nanocrystal/PNIPAM nanogels: Preparation,thermosensitive fluorescence performance and use as bioprobes for monitoring drug release

Novel core–shell LaF₃ : Eu³⁺ nanocrystals/PNIPAM nanogels were prepared by surface‐initiated living radical polymerization. The microstructure and performance of the LaF₃ : Eu³⁺ nanocrystals and the hybrid nanogels were characterized by transmission electron microscopy (TEM), X‐ray diffraction (XRD), X‐ray photoelectron spectrometer (XPS), and photoluminescence (PL). The thermosensitive fluorescence behaviors of the core–shell nanogels and the drug release behaviors were investigated by PL at various temperatures. The results suggested that the fluorescence performance of the nanogels was influenced greatly by the ambient temperature, either content of Aspirin absorbed in the nanogels. Compared to other reported systems, our discovery could tell how much the nanogels contain Aspirin by detecting the fluorescence intensity. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39930.     

Synthesis,pH sensitivity,and drug‐release behavior of acrylic acid and polyhedral oligomeric silsesquioxane copolymer

pH‐Sensitive organic–inorganic copolymers of hydrogels were developed as drug delivery systems (DDS) to improve the swelling behavior of polyacrylic acid (PAA). They were represented through FTIR, TGA and XRD characterization which revealed that the functional groups of methacryl‐phenyl polyhedral oligomeric silsesquioxane (POSS) were successfully added to the acrylic acid (AA) molecular chains through radical solution polymerization. The DSC test results indicate that the addition of POSS could improve the thermal properties of the copolymers. The swelling properties at the pH range of 1.25–8.01 exhibited the pH sensitivity of POSS/AA copolymers (POSS‐co‐AA) and the lower swelling ratio in acidic conditions indicated that the DDS had low amount of release in SGF; this phenomenon suggested that the copolymer was available as DDS of theophylline. And it was proved by drug release curve and scanning electron microscopy. Since the addition of POSS reduced the release rate of theophylline and prolonged the release time of the drug, the concentration range of theophylline could remain low for an extended duration. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Poly(methyl methacrylate)/poly(ethylene glycol)/poly(ethylene glycol dimethacrylate) micelles: Preparation,characterization, and application as doxorubicin carriers

A crosslinked amphiphilic copolymer [poly(ethylene glycol) (PEG)–poly(methyl methacrylate) (PMMA)–ethylene glycol dimethacrylate (EGDM)] composed of PMMA, PEG, and crosslinking units (EGDM) was synthesized by atom transfer radical polymerization to develop micelles as carriers for hydrophobic drugs. By adjusting the molar ratio of methyl methacrylate and EGDM, three block copolymer samples (P0, P1, and P2) were prepared. The measurement of gel permeation chromatography and ¹H‐NMR indicated the formation of crosslinked structures for P1 and P2. Fluorescence spectroscopy measurement indicated that PEG–PMMA–EGDM could self‐assemble to form micelles, and the critical micelle concentration values of the crosslinked polymer were lower than those of linear ones. The prepared PEG–PMMA–EGDM micelles were used to load doxorubicin (DOX). The drug‐loading efficiencies of P1 and P2 were higher than that of P0 because the crosslinking units enhanced the micelles' stability. With increasing drug‐loading contents, DOX release from the micelles in vitro was decreased, and in the crosslinked formulations, the release rate was also slower. An in vitro release study indicated that DOX release from the micelles for the linear samples was faster than that for crosslinked micelles. The drug feeding amount increased and resulted in an increase in the drug‐loading content, and the loading efficiency decreased. These PEG–PMMA–EGDM micelles did not show toxicity in vitro and could reduce the cytotoxicity of DOX in the micelles; this suggested that they are good candidates as stable drug carriers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39623.     

Hydrophobically graded polyester polyol acrylate polymers: Synthesis,characterization, and microencapsulation of sulfamethoxazole for controlled release application

Polyester polyol macromers were prepared by using diacid‐diol condensation reaction using succinic acid as the acid component and polyethylene glycol 200 (PEG 200) as the diol component. Replacing PEG 200 with increasing amounts of butanediol resulted in macromers, which upon acrylation of end hydroxy groups and polymerization resulted in polymers with graded hydrophobicity depending on the amount of butanediol present in the polymer. These polymers showed expected trends in water equilibrium swells, equilibrium water contact angles, and in vitro degradation times depending on the amount of modification with butanediol. These polymers were used to microencapsulate sulfamethoxazole as a model drug and the in vitro delivery of the drug also followed the expected trend depending on the polymer hydrophobicity. Thus, it was shown that it is possible to prepare polyesters of graded properties by judicious selection of diacids and diols. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4058–4065, 2006     

Garcinia xanthochymus mediated green synthesis of ZnO nanoparticles: Photoluminescence,photocatalytic and antioxidant activity studies

Green synthesis of multifunctional zinc oxide nanoparticles (ZnO Nps) was achieved employing water extract of Garcinia xanthochymus by solution combustion synthesis. The structure and morphology were determined by XRD, UV–visible and scanning electron microscopy studies. The ZnO Nps were evaluated for photoluminescence (PL), photocatalytic and antioxidant properties. The water extract was found to comprise significantly high amounts of polyphenols and flavonoids. Powder XRD studies indicate the formation of pure wurtzite structure with absorption maximum of 370 nm corresponding to band gap energy of 3.33 eV. SEM studies reveal the formation of spongy cave like structures. The PL spectra exhibited 4 emission edges at 397, 436, 556 and 651 nm upon excitation at 325 nm because of oxygen deficiencies and zinc interstitials. Nps exhibit remarkable photodegradation of methylene blue (MB) in presence of UV and sun light. They exhibit antioxidant activity by inhibiting the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. Therefore, the study reveals an efficient, ecofriendly and simple method for the green synthesis of multifunctional ZnO Nps.