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     

Formation of silver nanoparticles created in situ in an amphiphilic block copolymer film

In this work, silver nanoparticles were synthesized with an amphiphilic diblock copolymer, polystyrene‐block‐poly(1‐vinyl‐2‐pyrrolidone) (PS‐b‐PVP), as a template film. First, microphase‐separated amphiphilic PS‐b‐PVP (70 : 30 wt %) was synthesized through atom transfer radical polymerization. The self‐assembled block copolymer film was used to template the growth of silver nanoparticles by the introduction of a silver trifluoromethanesulfonate precursor and an ultraviolet irradiation process. The in situ formation of silver nanoparticles with an average size of 4–6 nm within the block copolymer template film was confirmed with transmission electron microscopy, ultraviolet–visible spectroscopy, and wide‐angle X‐ray scattering. Fourier transform infrared spectroscopy also demonstrated the selective incorporation and in situ formation of silver nanoparticles within the hydrophilic poly(1‐vinyl‐2‐pyrrolidone) domains, which were mostly due to the stronger interaction strength of the silver with the carbonyl oxygens of poly(1‐vinyl‐2‐pyrrolidone) in the block copolymer. This work provides a simple route for the in situ synthesis of silver nanoparticles within a polymer film. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Characterization of novel quaternary chitosan derivative nanoparticles loaded with protein

The objective of this work was to characterize a novel quaternary chitosan derivative [O‐(2‐hydroxyl) propyl‐3‐trimethyl ammonium chitosan chloride (O‐HTCC)] nanoparticle system. O‐HTCC nanoparticles were prepared with a simple and mild ionic gelation method upon the addition of a sodium tripolyphosphate solution to a low‐molecular‐weight O‐HTCC solution. Highly cationic chitosan nanoparticles were prepared. Bovine serum albumin (BSA), a model protein drug, was incorporated into the nanoparticles. The physicochemical properties of the nanoparticles were determined with transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared analysis, differential scanning calorimetry, and X‐ray diffraction (XRD) patterns. The results showed that increasing the BSA concentration from 1.5 to 2.5 mg/mL promoted the BSA encapsulation efficiency from 57.3% to 87.5% and the loading capacity from 70.2% to 99.5%. Compared with the chitosan nanoparticles, the O‐HTCC nanoparticles had lower burst release. TEM revealed that the BSA‐loaded O‐HTCC nanoparticles were smaller than the O‐HTCC nanoparticles when the BSA concentration was 1.5 mg/mL; SEM showed that the size of the BSA‐loaded O‐HTCC nanoparticles was mostly affected by the BSA concentration, and the increase in size occurred with the concentration increasing. Thermograms and XRD of the BSA‐loaded nanoparticles suggested that polyelectrolyte–protein interactions increased with the BSA concentration increasing and greater chain realignment in the BSA‐loaded nanoparticles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of an amphiphilic pluronic‐poly(D,L‐lactide‐co‐glycolide) copolymer and their nanoparticles as protein delivery systems

A new amphiphilic Pluronic (F68)‐PLGA copolymer, which can be used to prepare the stealth or long‐circulating nanoparticles, was synthesized with Pluronic (F68), DL ‐Lactide, and glycolide. The structures of Pluronic (F68)‐PLGA copolymer as the products were characterized with infrared spectrometry, nuclear magnetic resonance and their molecular weights were determined by gel permeation chromatography. Two methods, double emulsion (DE) and nanoprecipitation (NP), were employed to fabricate the polymeric nanoparticles. Bovine serum albumin (BSA) was loaded into nanoparticles as a model protein. Influence of the preparation conditions on the nanoparticles size, encapsulation efficiency, and release profile in vitro was investigated. They showed the entrapment efficiency of 42.9–63.4% and the average diameter of 119.1–342.8 nm depending on the fabrication technique of nanoparticles and the type of copolymer. The stability maintenance of BSA in the nanoparticle release in vitro was also measured via sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE), circular dichroism (CD), and fluorescence spectrometry. The results showed that the new copolymer could load BSA effectively and BSA kept stable after it was released from the nanoparticles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and crystallization behavior of acetal copolymer/silica nanocomposite by in situ cationic ring‐opening copolymerization of trioxane and 1,3‐dioxolane

The acetal copolymer/silica nanocomposite was prepared by in situ bulk cationic copolymerization of trioxane and 1,3‐dioxolane in the presence of nanosilica. The crystallization behavior of acetal copolymer/silica nanocomposite was studied by AFM, DSC, XRD, and CPOM, and the macromolecular structure of acetal copolymer/silica nanocomposite was characterized by FTIR and ¹H‐NMR. The ¹H‐NMR results showed that the macromolecular chain of acetal copolymer had more than two consecutive 1,3‐dioxolane units in an oxymethylene main chain, while that of acetal copolymer/silica nanocomposite had only one 1,3‐dioxolane unit in an oxymethylene main chain. There existed interaction between the macromolecular chains and nanoparticles (such as hydrogen bonds and coordination). On one hand, nanoparticles acted as nucleation center, which accelerated the crystallization rate but reduced the crystallinity. The spherulite sizes also decreased with addition of nanoparticles attributed to the nucleation effect. On the other hand, the presence of nanoparticles interrupted the spherical symmetry of the crystallite. In conclusion, the high surface energy and small scale of nanoparticles have a prominent impact on the polymerization mechanism and crystallization behavior of nanocomposite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of ZnO nanostructures templated using diblock copolymers

The development of self‐assembled ZnO nanoparticles within a diblock copolymer matrix using wet chemical processing specific to ZnO is reported. Diblock copolymers consisting of polynorbornene and poly(norbornene–dicarboxcylic acid) (NOR/NORCOOH) were synthesized with a block repeat unit ratio of 400 for the first block and 50 for the second block, to obtain spherical microphase separation. The block copolymer self‐assembly was used to template the growth of ZnO nanoparticles by introducing a ZnCl₂ precursor into the second polymer (NORCOOH) block at room temperature and processing the copolymer by wet chemical methods to substitute the chlorine atoms with oxygen. X‐ray photoemission spectroscopy (XPS) verified the conversion of ZnCl₂ to ZnO by monitoring the disappearance of the Cl 1s peak and the shift in the binding energy of the Zn 2p³ peak in the high‐resolution spectra. The substitution of Cl by O was found to be a highly preferential process, whereby only one approach using a weak base (NH₄OH) succeeded in effectively replacing Cl with O to result in spherical ZnO nanoparticles having a size ranging from 7 to 15 nm, as determined by transmission electron microscopy. The development of such block copolymer‐templated ZnO nanoparticles% is important in enabling the functionalization of large‐area nanodevice technologies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1058–1061, 2003     

Preparation and characterization of poly{[α‐maleic anhydride‐ω‐methoxy‐poly(ethylene glycol)]‐co‐(ethyl cyanoacrylate)} copolymer nanoparticles

Poly{[α‐maleic anhydride‐ω‐methoxy‐poly(ethylene glycol)]‐co‐(ethyl cyanoacrylate)} (PEGECA) copolymers were prepared by radical polymerization of macromolecular poly(ethylene glycol) monomers (PEGylated) and ethyl 2‐cyanoacrylate in solvent. The structures of the copolymer were characterized by Fourier‐transform infrared (FTIR) and proton nuclear magnetic resonance (¹H‐NMR). The morphology and size of the PEGECA nanoparticles prepared by nanoprecipitation techniques were investigated by transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS) methods. The results show that the PEGECA can self‐assemble into highly stable nanoparticles in aqueous media, and inner core and outer shell morphology. The size of the nanoparticles was strongly influenced by the solvent character and the copolymer concentration in the organic solvents. A hydrophobic drug, ibuprofen, was effectively incorporated into the nanoparticles, which provides a delivery system for ibuprofen and other hydrophobic compounds. Copyright © 2005 Society of Chemical Industry     

Preparation of nanoparticles composed of chitosan and its derivatives as delivery systems for macromolecules

Three different kinds of nanoparticles for paracellular transport were prepared using a simple and mild ionic‐gelation method. Sodium tripolyphosphate (TPP) as crosslinking agent was added into three kinds of solutions, which were chitosan solution, physical blending solution of chitosan, and glycidyl trimethylammonium chloride (GTMAC), and O‐(2‐hydroxyl) propyl‐3‐trimethyl ammonium chitosan chloride (O‐HTCC) solution respectively. O‐HTCC was synthesized by coupling of GTMAC to chitosan whose functional groups of the NH₂ groups were protected. The nanoparticles were characterized by transmission electron microscopy, atomic force microscopy, photon correlation spectroscopy, and zeta potential measurement. The results showed that increasing TPP concentration promoted the size of chitosan nanoparticles, a decrease in the size of O‐HTCC nanoparticles incurred on the contrary. The size of O‐HTCC nanoparticles is slightly bigger than that of pure chitosan nanoparticles, and smaller than that of physical blending nanoparticles (PBN). Bovine serum albumin (BSA), as a model protein drug, was incorporated into the nanoparticles. Compared with chitosan nanoparticles and PBN, high BSA loading efficiency (87.5%) and loading capacity (99.5%) are achieved by quaternized chitosan (O‐HTCC) nanoparticles, and the release profile of BSA from nanoparticles has an obvious burst effect and a slowly continuous release phase followed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Hyperbranched poly (amine-ester)-poly(ε-caprolactone) copolymer and their nanoparticles as camptothecin delivery system

A new amphiphilic hyperbranched poly (amine-ester)-poly(ε-caprolactone) copolymer (HPAE-co-PCL) was synthesized by ring-opening polymerization of ε-caprolactone and branched poly (amine-ester) (HPAE-OHs) with Sn(Oct)₂ as catalyst. The chemical structures of copolymers were determined by FT-IR, ¹H-NMR (¹³C-NMR), thermo gravimetric analysis apparatus (TGA) and differential scanning calorimetry (DSC). Camptothecin (CPT)-loaded copolymer nanoparticles were prepared by the oil-in water (o/w) emulsion technique method. Their physicochemical characteristics, e.g. morphology and nanoparticles size distribution were then evaluated by means of fluorescence spectroscopy, environmental scanning electron microscopy (ESEM), and dynamic light scattering (DLS). CPT-loaded nanoparticles assumed a spherical shape and have unimodal size distribution. It was found that the chemical composition of the nanoparticles was a key factor in controlling nanoparticles size, drug-loading content, and drug release behavior. As the molar ratio of ε-caprolactone to HPAE increased, the nanoparticles size and drug-loading content increased, and the drug release rate decreased. The antitumor activity of the CPT-loaded HPAE-co-PCL nanoparticles against human hepatoma HEPG2 cells was evaluated by 3-(4, 5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. The CPT-loaded HPAE-co-PCL nanoparticles showed comparable anticancer efficacy with the free drug.     

Encapsulation of BSA in polylactic acid–hyperbranched polyglycerol conjugate nanoparticles: preparation, characterization, and release kinetics

Nanoparticles based on an amphiphilic copolymer with polylactic acid (PLA) grafted onto hyperbranched polyglycerol (HPG) were prepared by the use of BSA as a model protein. The characteristics of the nanoparticles were evaluated using particle size analyzer, transmission electron microscopy, and X-ray photoelectron spectroscopy. The secondary structure of BSA released from nanoparticles were analysed by circular dichroism experiments. Cell viability of nanoparticles was also evaluated by using NIH 3T3 cells. The mechanism of BSA release was studied by fitting experimental data to three model equations. Results indicated that BSA diffusion and the polymeric relaxation jointly governed the overall release process. The detailed analysis of BSA release was performed using the first-order kinetic model equation, which gave a good fit to the experimental release data. The influence of different copolymer structures and BSA loading capacities on release profiles were also evaluated for the potential of using nanoparticles as controlled release protein delivery systems.     

Synthesis of chitosan‐graft‐β‐cyclodextrin for improving the loading and release of doxorubicin in the nanopaticles

Chitosan‐graft‐β‐cyclodextrin (CS‐g‐β‐CD) copolymer was synthesized by conjugating β‐cyclodextrins to chitosan molecules through click chemistry. The copolymer structure was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). CS‐g‐β‐CD/CMC nanoparticles were prepared by a polyelectrolyte complexation process in aqueous solution between CS‐g‐β‐CD copolymer and carboxymethyl chitosan (CMC), which was used to load anticancer drug (Doxorubicin hydrochloride, DOX·HCl) with hydrophobic group. The particle size, surface charge, zeta potential, and morphology of the nanoparticles were characterized with dynamic light scattering. The drug loading efficiency and in vitro release of DOX·HCl of the nanoparticles were measured by ultraviolet spectrophotometer. The results demonstrated that the size, surface charge and drug loading efficiency of the nanoparticles could be modulated by the fabrication conditions. The drug loading efficiency of CS‐g‐β‐CD/CMC nanoparticles was improved from 52.7% to 88.1% because of the presence of β‐CD moieties with hydrophobic cavities, which can form inclusion complexes with the drug molecules. The in vitro release results showed that the CS‐g‐β‐CD/CMC nanoparticles released DOX·HCl in a controlled manner, importantly overcoming the initial burst effect. These nanoparticles possess much potential to be developed as anticancer drug delivery systems, especially those drugs with hydrophobic group. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41034.     

Cu(II) ions removal from wastewater using starch nanoparticles (SNPs): An eco-sustainable approach

The complex structured starch particles were reduced to the nanoscale size range through hydrolysis utilizing low concentration acid assisted by ultrasound irradiation. The synthesized starch nanoparticles (SNPs) were characterized by transmission electron microscopy (TEM), Fourier-transform infrared (FTIR), and X-ray diffraction (XRD) techniques. The synthesized SNPs possessed surface activated entities, as many cationic functional groups were confirmed through the FTIR spectrum. Also, these SNPs were effectively utilized to separate heavy Cu metal ions from the synthetic ion solution. The SNPs were characterized using field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis for the surface modification after the adsorption process. The weak electrostatic interaction between the SNP surface and Cu ion was confirmed by the XPS spectrum and energy-dispersive X-ray spectroscopy. The maximum efficiency of Cu ions removal was about 93% at an optimal pH 5 and 25 mg/ml dosage. The adsorption equilibrium was obtained in 60 min. The nitrogen isotherm BET analysis of SNPs after adsorption shows a higher specific surface area of 18.552 m²/g, attributed to the interaction and presence of Cu ions on the SNP surface. The process feasibility was validated by the Langmuir isotherm model. The process exhibits pseudo-second-order adsorption kinetics and follows the Langmuir isotherm. The R_L predicted by the Langmuir isotherm mechanism is 0.017, implying favourable adsorption. The process is reproducible and allows for the separation of heavy metal ions from the wastewater through biosorption effectively.     

Fluorescence study of interaction between an anionic conjugated polyelectrolyte and bovine serum albumin

The interaction between an anionic conjugated polyelectrolyte, poly[9,9-bis(3′-butyrate)fluoren-2,7-yl] sodium (BBS-PF), and bovine serum albumin was investigated by fluorescence spectroscopy. The emission of BBS-PF was effectively quenched by BSA with a quenching constant K _SV of 3.1 × 10⁷ L/mol when BSA was at nanomolar concentrations, but the emission increased when the concentration of BSA was at micromolar level. The excitation band of BBS-PF blue-shifted when the emission was quenched where the negatively charged BSA induced the aggregation of BBS-PF, yet the excitation band of BBS-PF red-shifted when the emission increased where the BSA acted as a surfactant and formed hydrophobic interaction with BBS-PF. BBS-PF could also quench BSA through energy transfer by resonance with a quenching constant K _SV of 1.1 × 10⁶ L/mol. The emission band changes of BSA reflected the conformation transitions of BSA from class II to class I and the binding of BBS-PF with BSA made the BSA more folded.     

The interaction between bovine serum albumin and the self-aggregated nanoparticles of cholesterol-modified O-carboxymethyl chitosan

The interaction between bovine serum albumin (BSA) and self-aggregated nanoparticles of cholesterol-modified O-carboxymethyl chitosan (CCMC) with different degrees of substitution (DS) of cholesterol moiety was studied by transmission electron microscopy (TEM), fluorescence quenching method and circular dichroism (CD) measurement. This interaction was started at the disaggregation of CCMC self-aggregated nanoparticles and reached equilibrium after 3-4 h. The apparent quenching constant (K_q) between BSA and CCMC self-aggregated nanoparticles calculated by the modified Stern-Volmer plot increased from 4.14 × 10⁴ to 1.95 × 10⁵ M⁻¹ with DS of cholesterol moiety increasing from 3.2% to 9.8%, whereas the fraction of tryptophan residues in BSA molecule involved in the interaction decreased at the same time. Compared with free BSA, the relative α-helix content of BSA decreased and the unfolding of BSA by a denaturant such as urea was largely suppressed upon interaction with CCMC self-aggregated nanoparticles. DS of cholesterol moiety significantly affected the interaction between BSA and CCMC self-aggregated nanoparticles.     

Coloration of Apocynum venetum/cotton blends with an acid dye through combined pretreatment using cationic nanoparticles

Cationic copolymer nanoparticles were used to modify Apocynum venetum/cotton blended fabrics. The modified blends were then dyed using CI Acid Red 14. In order to enhance the colour performance, the effects of combined pretreatment using nanoparticles and sodium hydroxide (NaOH) or carboxymethylcellulose (CMC) or plasma were investigated. The results show that combined pretreatment with NaOH and nanoparticles improved the dyeing effect. The optimum concentrations of NaOH and nanoparticles were 100 and 2 g l⁻¹ respectively. In addition, using CMC to pretreat the fabrics could also improve the acid dyeing performance. However, the combination of plasma pretreatment and cationic nanoparticle modification produced the best colour performance for acid-dyed A. venetum/cotton blends. The dye exhaustion rate is highest (up to 95%) with plasma pretreatment. Scanning electron microscopy revealed that combined treatment with plasma and nanoparticles resulted in a far greater number of nanoparticles being deposited on the fibre surface. X-ray photoelectron spectroscopy indicated that the pretreatments with different procedures significantly changed the chemical components of the fibre surfaces. The aromatic rings of acid dye molecules covered the fibre surfaces after plasma and nanoparticle pretreatment and acid dyeing.     

Similarly sized protein separation of charge‐selective ethylene‐vinyl alcohol copolymer membrane by grafting dimethylaminoethyl methacrylate

Similarly sized protein separation was investigated using a charge‐selective membrane, which prepared by grafting dimethylaminoethyl methacrylate (DMAEMA) onto ethylene vinyl alcohol copolymer (EVAL) membrane. Bovine serum albumin (BSA) and bovine hemoglobin (BHb) was used as model proteins. P(DMAEMA), the weak cationic polyelectrolyte with ionizable tertiary amine groups, contributed to the charge‐selective separation for BSA and BHb. At pH 6.0, the grafted EVAL membrane surface was positively charged and BSA was negatively charged, while BHb was positively charged. The BSA was adsorbed onto the membrane surface due to electrostatic interaction and the BHb passed through the membrane into the permeate. The charge‐selective behavior resulted in the separation of the similarly sized protein. The maximum separation factors of static adsorption separation for model protein and binary mixture were 32.4 and 37.2, respectively. In the dynamic separation process, the maximum separation factor value was 6.2. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46374.     

Silver ferrite and cobalt ferrite dispersed castor oil polyurethane nanocomposites: Quenching studies of bovine serum albumin

The use of renewable resource is a strategic opportunity to meet growing demands of eco-friendly materials. The present study reports the synthesis of castor-oil-based polyurethane (COPU), and its nanocomposites with CoFe₂O₄ and AgFeO₂ via sonication technique. Formation of the nanocomposite was confirmed by IR analysis while UV–visible studies revealed encapsulation of the ferrite particles by COPU. The interaction between COPU, AgFeO₂, CoFe₂O₄, and their nanocomposites with bovine serum albumin (BSA) was also investigated by fluorescence spectroscopy which revealed static quenching of BSA through complex formation. The quenching rate for COPU was determined to be 1.98?×?10⁴?LM^?1 while for pure CoFe₂O₄ and AgFeO₂, it was found to be 3?×?10⁴?LM^?1 and 3.2?×?10⁴?LM^?1, respectively. The interaction of BSA particularly with silver and cobalt ferrite nanoparticles within COPU matrix was found to be promising. It was found that by controlling the loading of ferrite in COPU matrix, desired binding could be achieved.     

Synthesis and characterization of star‐branched polyisobutylene with SIpS triblock copolymer core

Well‐defined polystyrene‐b‐polyisoprene‐b‐polystyrene (SIpS) triblock copolymers with different microstructures were synthesized by living anionic polymerization. The synthesis of star‐branched polyisobutylene (PIB) was accomplished by the cationic polymerization in 2‐chloro‐2,4,4‐trimethylpentane/titanium tetrachloride/SIpS triblock copolymer/2,6‐di‐tert‐butylpyridine initiating system. The double bonds in SIpS triblock copolymer were activated as starting points for isobutylene polymerization. The formation of star‐branched architecture was demonstrated by size‐exclusion chromatography with quadruple detection: refractive index, multiangle laser light scattering, viscometric, and ultraviolet detectors. SIpS triblock copolymer with high 3,4‐PIp content is more reactive than that with high 1,4‐PIp content in cationic initiating stage. The yields of star‐branched PIB were remarkably dependent on the reaction time of TMP⁺ with SIpS. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and Microstructural Investigations of Organometallic Pd(II) Thiol-Gold Nanoparticles Hybrids

In this work the synthesis and characterization of gold nanoparticles functionalized by a novel thiol-organometallic complex containing Pd(II) centers is presented. Pd(II) thiol, trans, trans-[dithiolate-dibis(tributylphosphine)dipalladium(II)-4,4′-diethynylbiphenyl] was synthesized and linked to Au nanoparticles by the chemical reduction of a metal salt precursor. The new hybrid made of organometallic Pd(II) thiol-gold nanoparticles, shows through a single S bridge a direct link between Pd(II) and Au nanoparticles. The size-control of the Au nanoparticles (diameter range 2–10 nm) was achieved by choosing the suitable AuCl₄ ⁻/thiol molar ratio. The size, strain, shape, and crystalline structure of these functionalized nanoparticles were determined by a full-pattern X-ray powder diffraction analysis, high-resolution TEM, and X-ray photoelectron spectroscopy. Photoluminescence spectroscopy measurements of the hybrid system show emission peaks at 418 and 440 nm. The hybrid was exposed to gaseous NO _x with the aim to evaluate the suitability for applications in sensor devices; XPS measurements permitted to ascertain and investigate the hybrid –gas interaction.     

Surface modification of starch nanocrystals through ring‐opening polymerization of ε‐caprolactone and investigation of their microstructures

Bionanoparticles of starch obtained by submitting native potato starch granules to acid hydrolysis conditions. The resulted starch nanoparticles were used as core or macro initiator for polymerization of ε‐caprolactone (CL). Starch nanoparticle‐g‐polycaprolactone was synthesized through ring‐opening polymerization (ROP) of CL in the presence of Sn(Oct)₂ as initiator. The detailed microstructure of the resulted copolymer was characterized with NMR spectroscopy. Thermal characteristic of the copolymer was investigated using DSC and TGA. By introducing PCL, the range of melting temperature for starch was increased and degradation of copolymer occurred in a broader region. X‐ray diffraction and TEM micrographs confirmed that there was no alteration of starch crystalline structure and morphology of nanoparticles, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008