Dendrimer as nanocarrier for drug delivery

Dendrimers are novel three dimensional, hyperbranched globular nanopolymeric architectures. Attractive features like nanoscopic size, narrow polydispersity index, excellent control over molecular structure, availability of multiple functional groups at the periphery and cavities in the interior distinguish them amongst the available polymers. Applications of dendrimers in a large variety of fields have been explored. Drug delivery scientists are especially enthusiastic about possible utility of dendrimers as drug delivery tool. Terminal functionalities provide a platform for conjugation of the drug and targeting moieties. In addition, these peripheral functional groups can be employed to tailor-make the properties of dendrimers, enhancing their versatility. The present review highlights the contribution of dendrimers in the field of nanotechnology with intent to aid the researchers in exploring dendrimers in the field of drug delivery.     

PCL/poloxamer 188 blend microsphere for paclitaxel delivery: Influence of poloxamer 188 on morphology and drug release

A novel controlled release system, paclitaxel‐loaded poly (ε‐caprolactone) (PCL)/poloxamer 188 (Pluronic F68, F68) blend microspheres is proposed in the present work. F68 was incorporated into PCL matrices as both a pore‐forming agent and a drug releasing enhancer. Paclitaxel‐loaded PCL/F68 blend microspheres with different amounts of F68 were prepared by the oil‐in water (O/W) emulsion/solvent evaporation method. Characterization of the microspheres followed to examine the particle size, the drug encapsulation efficiency, the surface morphology, and in vitro release behavior. The influences of F68 on microsphere morphology and paclitaxel release are discussed. The porosity of the surface of PCL/F68 blend microspheres and the release rate of paclitaxel from the PCL/F68 blend microspheres increased as the initial amount of blended F68 increased. Faster and controlled release was achieved in comparison with the PCL microspheres. Through this study, the developed microporous PCL/F68 blend microspheres could be used as a drug delivery system to enhance and control drug release in the future. © 2007 Wiley Periodicals, Inc. JAppl Polym Sci 104: 1895–1899, 2007     

Surface decoration of magnetic nanoparticles with folate-conjugated poly(N-isopropylacrylamide-co-itaconic acid): A facial synthesis of dual-responsive nanocarrier for targeted delivery of doxorubicin

The aim of study was to develop a novel drug nanocarrier via facile coating of a folate-conjugated dual-responsive copolymer with carboxylic functional groups on the surface of magnetic nanoparticles for the efficient loading and cell-specific targeting of a positively charged anticancer agent. The nanocarrier exhibited many favorable capabilities such as narrow distributed nano-ranged size (～30 nm), high drug loading capacity (～65%), and stimuli-responsive drug release. The results of various cell cytotoxicity studies such as MTT assay, DAPI staining, and flow cytometry concluded that the developed smart nanocarrier paves a way for efficient cancer therapy by the multiple targeting strategies.     

The role of the ratio (PEG:PPG) of a triblock copolymer (PPG‐b‐PEG‐b‐PPG) in the cure kinetics,miscibility and thermal and mechanical properties in an epoxy matrix

The aim of this study was to evaluate the role of different poly(ethylene glycol):poly(propylene glycol) (PEG:PPG) molar ratios in a triblock copolymer in the cure kinetics, miscibility and thermal and mechanical properties in an epoxy matrix. The poly(propylene glycol)‐block‐poly(ethylene glycol)‐block‐poly(propylene glycol) (PPG‐b‐PEG‐b‐PPG) triblock copolymers used had two different molecular masses: 3300 and 2000 g mol^?1. The mass concentration of PEG in the copolymer structure played a key role in the miscibility and cure kinetics of the blend as well as in the thermal–mechanical properties. Phase separation was observed only for blends formed with the 3300 g mol^?1 triblock copolymer at 20 wt%. Concerning thermal properties, the miscibility of the copolymer in the epoxy matrix reduced the T_g value by 13 °C, although a 62% increase in fracture toughness (K_IC) was observed. After the addition of PPG‐b‐PEG‐b‐PPG with 3300 g mol^?1 there was a reduction in the modulus of elasticity by 8% compared to the neat matrix; no significant changes were observed in T_g values for the immiscible system. The use of PPG‐b‐PEG‐b‐PPG with 2000 g mol^?1 reduced the modulus of elasticity by approximately 47% and increased toughness (K_IC) up to 43%. Finally, for the curing kinetics of all materials, the incorporation of the triblock copolymer PPG‐b‐PEG‐b‐PPG delayed the cure reaction of the DGEBA/DDM (DGEBA, diglycidyl ether of bisphenol A; DDM, Q3‐4,4′‐Diaminodiphenylmethane) system when there is miscibility and accelerated the cure reaction when it is immiscible. All experimental curing reactions could be fitted to the Kamal autocatalytic model presenting an excellent agreement with experimental data. This model was able to capture some interesting features of the addition of triblock copolymers in an epoxy resin. © 2018 Society of Chemical Industry     

Polyacrylamide‐grafted carboxymethyl cellulose: Smart pH‐sensitive hydrogel for protein concentration

A novel application, utilizing polyacrylamide‐g‐carboxymethyl cellulose (CMC‐g‐PAM) in concentrating dilute solutions of Bovine serum albumin (BSA), was investigated. The grafting reaction parameters were investigated and the hydrogel smartness was verified. FT‐IR proved that the grafting reaction occurred between the hydroxyl group located in anhydroglucose C₂ position of CMC and the π‐bond of PAM and SEM confirmed a changed morphology to a fibrillar structure. The pH sensitivity was proved; as the grafted polymer attained its maximum swelling at pH 7.2 while the minimum swelling was observed under acidic conditions (pH 1‐3). The rate of water uptake in the grafted polymer hydrogel was higher than that of the homopolymer hydrogel and the swelling behaviors of both hydrogels obeyed second‐order kinetics. The tested hydrogel showed a high potency towards concentrating BSA solutions with a concentration factor of 1 to 4.5 times and recovery of 60–90%. The concentration factor increased linearly with increasing both the polymer concentration and the process time and decreased with the increase in the protein concentration. The grafted polymer had stable efficiency in the concentration process for 20 cycles. The obtained results have recommended the employment of the prepared CMC‐g‐PAM hydrogel in the down stream protein concentration process in the industrial scale. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Preparation,characterization, and in vitro bioactivity of magnetic co-polymer [N,N-dimethylaminopropylacrylamide-co-1-allylimidazole] as a new nanocarrier for delivery of cefotaxime

In this research, new magnetic nanoparticles (MNPs) conjugated radical co-polymerization with N, N-dimethylaminopropylacrylamide (N, N-DMAPAAm) as a thermosensitive monomer and 1-allylimidazole (AI) as a cross-linker agent was prepared as a magnetic nanocomposite (MNC). The synthesized MNC were characterized by Fourier transform infrared spectroscopy, Elemental analysis (CHN), Field emission scanning electron microscopy, Vibrating Sample Magnetometer, and Thermo Gravimetric Analysis. Cefotaxime was selected as a model drug and was loaded into the synthesized polymer. The main factors of adsorption process such as pH, contact time, temperature, and eluent were evaluated and optimized. The mechanism of cefotaxime adsorption is explained by Langmuir isotherm. Also, in vitro cefotaxime delivery in the simulated gastric and intestinal fluids was investigated. The drug release profile revealed that about 30.35% of the adsorbed cefotaxime was released in the first 30 min. at pH =1.2 (simulated gastric fluid) and 62.65% was released during 15 h at pH =7.4 (simulated intestinal fluid).     

Methoxy poly(ethylene glycol)‐block‐poly(D,L‐lactic acid) copolymer nanoparticles as carriers for transdermal drug delivery

This work evaluates the transdermal drug delivery properties of amphiphilic copolymer self‐assembled nanoparticles by skin penetration experiments in vitro. Paclitaxel‐loaded methoxy poly(ethylene glycol)‐block‐poly(D ,L ‐lactic acid) diblock copolymer nanoparticles (PNPs) were prepared by a solid dispersion technique and were applied to the surface of excised full‐thickness rat skin in Franz diffusion cells. HPLC, transmission electron microscopy, Fourier transform infrared spectroscopy and ¹H NMR were used to assay the receptor fluid. The results show that the amphiphilic copolymer nanoparticles with the entrapped paclitaxel are able to penetrate rat skin. Ethanol can improve the delivery of PNPs and increase the cumulative amount of paclitaxel in the receptor fluid by 3 times. Fluorescence microscopy measurements indicate that the PNPs can penetrate the skin not only via appendage routes including sweat ducts and hair follicles but also via epidermal routes. Copyright © 2007 Society of Chemical Industry     

Starch–acrylics graft copolymers and blends: Synthesis,characterization, and applications as matrix for drug delivery

A series of acrylic monomers–starch graft copolymers were prepared by ceric ion initiation method by varying the amount of monomers. These graft copolymers were characterized by IR and ¹³C‐NMR spectroscopy. It was seen that as the concentration of monomer [acrylic acid (AA), methacrylic acid (MA), and methyl methacrylate (MMA)] increased the percent add‐on increased in all the graft copolymers, whereas grafting efficiency increased initially but showed a slight decrease with further increase in the monomer concentration (except for MMA). The release rate of paracetamol as a model drug from graft copolymers as well as their blends was studied at two different pH, 1.2 and 7.4, spectrophotometrically. The release of paracetamol in phosphate buffer solution at pH 1.2 was insignificant in the first 3 h for St‐g‐PAA‐ and St‐g‐PMA‐graft copolymers, which was attributed to the matrix compaction and stabilization through hydrogen bonding at lower pH. At pH 7.4, the release rate was seen to decrease with increase in add‐on. The tablet containing poly(methyl methacrylate) (PMMA) did not disintegrate at the end of 30–32 h, which may be attributed to the hydrophobic nature of PMMA. These results indicate that the graft copolymers may be useful to overcome the harsh environment of the stomach and can be used as excipients in colon‐targeting matrices. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polyacrylamide‐g‐alginate‐based electrically responsive hydrogel for drug delivery application: Synthesis,characterization, and formulation development

An electrically responsive hydrolyzed polyacrylamide‐grafted‐sodium alginate (H‐PAAm‐g‐SA)‐based membrane‐controlled transdermal drug delivery systems were developed and evaluated. The grafting reaction was confirmed by Fourier transform infrared spectroscopy, elemental analysis, and thermogravimetric analysis. On application of electric stimulus, the swollen H‐PAAm‐g‐SA hydrogel was deswelled in the vicinity of electrodes. The drug release was greater in the presence of electric stimulus when compared with passive diffusion, and it was found to be dependent on the applied electric current strength, concentration of H‐PAAm‐g‐SA copolymer in the reservoir, and cross‐link density of rate‐controlling membrane. A pulsatile pattern of drug release was observed when the electric stimulus was switched “on” and “off.” The skin histopathology study suggested that, after application of an electrical stimulus, changes were in the structure of stratum corneum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Enzyme–magnetic nanoparticle hybrids: new effective catalysts for the production of high value chemicals

Magnetic nanoparticles (5–100 nm in diameter) offer the science community a new dimension in many key areas of research, notably nano‐medicine. However, use as catalyst support material (including enzyme immobilization) has largely been overlooked despite the benefits of a facile catalyst separation post‐reaction with reuse through the application of an external magnetic field. This is largely due to the high cost associated with magnetic nanoparticle synthesis in addition to enzyme operating costs. This can, however, be compensated for by effective catalyst recycling in the production of high value chemicals, particularly chiral drugs and their intermediates, circumventing laborious multi‐stage separation and purification procedures in conventional synthesis. Indeed, enzymes (such as lipase) on magnetic carriers have shown prolonged activity in organic solvents, even after recycling, when compared with free enzymes. Further developments can be directed at multi‐functional magnetic nanoparticles with the creation of a reactant‐specific micro‐environment to facilitate multi‐stepped reactions. The potential of enzyme‐magnetic nanoparticle hybrids is discussed and applications in the synthesis of fine chemicals, including precursors for drugs, are identified. Copyright © 2012 Society of Chemical Industry     

Self‐assembly of alginate/polyethyleneimine multilayer onto magnetic microspheres as an effective adsorbent for removal of anionic dyes

A novel magnetic adsorbent alginate/polyethyleneimine (ALG/PEI)_n/MN was developed for removal of anionic dyes from aqueous solution in this study. (ALG/PEI)_n/MN was prepared by depositing ALG/PEI multi‐layers onto amine‐modified Fe₃O₄ microspheres through layer‐by‐layer method. The morphologies and structures of the adsorbent were characterized by scanning electron microscopy, X‐ray diffractometer, and Fourier transform infrared spectrometer, respectively, and its performance in adsorption of anionic dye (acid orange 10, AO10) under varied experimental conditions were also investigated. The results revealed that the uptake capacity of AO10 by (ALG/PEI)_n/MN increased with the number of coated (ALG/PEI) bilayer on the adsorbents, and the maximum adsorption capacity for AO10 by (ALG/PEI)₄MN was 246.3 mg g^?1 at 25 °C. The adsorption process was exothermic and well described by the pseudo‐second order kinetic model and the Langmuir isothermal model. Moreover, (ALG/PEI)₄/MN showed good reusability and excellent magnetic separability. All the results demonstrate that (ALG/PEI)₄/MN is a potential recyclable adsorbent for removal of anionic dyes from wastewater. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45876.     

Structural study of a series of ethylene-tetrafluoroethylene copolymers with various ethylene contents, Part 1: Structure at room temperature investigated for uniaxially-oriented samples by an organized combination of 2D-WAXD/SAXS and IR/Raman spectra

The X-ray fiber diagrams, polarized infrared/Raman spectra, and small-angle X-ray scattering data have been successfully measured for a series of uniaxially-oriented ethylene (E)-tetrafluoroethylene (TFE) random copolymers. The difference in crystal structure and morphology has been investigated. All the samples of E/TFE copolymer were found to take the planar-zigzag conformation at room temperature except pure polytetrafluoroethylene case. The layer line intensities of the X-ray fiber diagram and the 00l reflection intensities were found to change systematically. From this, the E and TFE sequences were considered to be included commonly in a crystal lattice. The detailed investigation of the polarized infrared and Raman spectra allowed us to assign the bands to some characteristic structures. These can be used effectively in the study of structural changes occurring in the phase transition of these copolymer samples. The 2-dimensional small-angle X-ray scattering patterns were compared among the copolymers and the difference in stacked lamellar structure has been discussed.     

Synthesis and characterization of an amphiphilic hyperbranched poly(amine‐ester)‐co‐D,L‐lactide (HPAE‐co‐PLA) copolymers and their nanoparticles for protein drug delivery

A series of hyperbranched poly(amine‐ester)‐co‐D ,L ‐lactide (HPAE‐co‐PLA) copolymer were synthesized by ring‐opening polymerization of D ,L ‐lactide with Sn(Oct)₂ as catalyst to a fourth generation branched poly(amine‐ester) (HPAE‐OHs4). The chemical structures of copolymers were determined by FTIR, ¹H‐NMR, ¹³C‐NMR, and TGA. Double emulsion (DE) and nanoprecipitation (NP) method were used to fabricate the nanoparticles of these copolymers encapsulating bovine serum albumin (BSA) as a model. DSC thermo‐grams indicated that the nanoparticles with BSA kept stable below 40°C. Different factors which influence on particular size and encapsulation efficiency (EE) were investigated. Their EE to BSA could reach 97.8% at an available condition. In vitro release behavior of NPs showed a continuous release after a burst release. The stability maintenance of BSA in the nanoparticle release in vitro was also measured via circular dichroism and fluorescence spectrometry. The results showed that the copolymer nanoparticles have a promising potential in protein delivery system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

An effective strategy to enhance the electrochemical performance of LiNi0.6Mn0.2Co0.2O2: Optimizing a Li diffusion pathway via magnetic alignment of single-crystal cathode material under an ordinary 0.4-T magnetic field

A strategy to enhance the electrochemical performance of a single-crystal LiNi_xMn_yCo_zO₂ (NCM) electrode is proposed herein based on a preferred orientation of a Li diffusion pathway along the working direction under an ordinary 0.4-T magnetic field. Hexagonal NCM622 single crystals can be aligned along their crystallographic c-axis parallel to the applied magnetic field because the crystal has an easy magnetization axis along the c-axis. The horizontal magnetic field–oriented NCM622 cathode (HMFC) shows inhibited polarization and increased lithium-ion conductivity. The suppressed polarization promotes cyclability, increasing the specific capacity from 157.93 to 168.75 mAhg^?1 after the 100th cycle at 0.5 C. Furthermore, the increased diffusion coefficient (from 3.06 × 10^?10 cm²s^?1 to 7.12 × 10^?10 cm²s^?1) causes substantial improvement in the rate performance, achieving a high specific capacity of 130.77 mAhg^?1 at 10 C, while the electrode without magnetic treatment achieves a specific capacity of only 115.88 mAhg^?1. Owing to such a superior electrochemical performance, the HMFC electrodes show high potential for lithium-ion batteries in the EV industry. Decreasing the magnetic field from 6 to 0.4 T for cathode alignment facilitates the applicability of the proposed strategy to production lines of battery plants using commercially available permanent magnets because a magnetic field of 0.4 T is easily achievable.     

Divinyl-terminated polysiloxane as an effective polyacrylates modifier for pigment printing: A study with different molecular weights and quantities

Polyacrylates binder is used as an environmental approach for pigment printing. However, the poor water resistance and abrasive resistance of it makes this technique limited. In this study, divinyl-terminated polysiloxane (Divi-PDMS) had been used to modify polyacrylates by miniemulsion polymerization. The conversion and coagulation of miniemulsion polymerization were evaluated by gravimetry method, the colloid properties of prepared latexes were obtained and the structures were confirmed by Fourier transformed infrared spectroscopy and NMR. Surface properties of latex films were investigated in terms of dynamic water contact angle, water absorption, and mechanical tensile properties. The results show that the polymerization has good stability, and the product has good phase separation of polysiloxane, which results in increased hydrophobicity and toughness of the film. The film with low-molecular weight and 8% dosage of Divi-PDMS has better hydrophobicity and toughness. The product is applied to pigment printing with better wet rubbing fastness and soft handle compared with the unmodified binder. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47961.     

Chitosan‐magnetite nanocomposites for effective removal of urea in “magnetic hemodialysis therapy”: A novel concept

The present study explores the possibilities of using chitosan‐magnetite (CM) nanocomposites for removal of urea in blood serum. The CM nanocomposites, with an average diameter in the range of 12–33 nm, were characterized by transmission electron microscopic and selected area electron diffraction analysis. The particles demonstrate fair ability to remove urea in human blood serum. The maximum removal efficiency was nearly 26%, when 200 mg of CM nanocomposites were allowed to agitate with 25 mL of urea solution of concentration 100 mg/dL. The CM nanocomposites could be easily removed by applying moderate magnetic field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009