Search

To improve the utilization rate of apple pomace and the catalytic stability and recycling performance of gold nanoparticles (AuNPs), as well as realize the high value utilization of inexpensive materials and the reuse of expensive materials, a recyclable AuNP catalyst based on hyperbranched polyethyleneimine-dialdehyde cellulose (HPEI-DAC) was developed. We used apple pomace as raw material to extract cellulose and oxidize it into easily modifiable DAC. A novel HPEI-DAC carrier with both reduction performance and easy separation performance was successfully prepared by grafting HPEI onto DAC through a Michael addition reaction. Taking advantage of the reduction properties and special topology of HPEI-DAC, AuNPs with high stability were prepared in situ. The prepared AuNPs/HPEI-DAC had high catalytic activity and reusability, which could realize the catalytic reduction of 4-nitrophenol (4-NP) and the recovery of AuNPs after catalysis. At 25 ℃, the catalytic efficiency of AuNPs/HPEI-DAC only decreased from 100% to 91% after being reused 6 times that was, its catalytic activity did not decrease significantly. These results show that the catalyst has excellent catalytic performance and reusability in reducing 4-NP organic pollutants and is expected to be used as an ideal catalyst in environmental treatment and other fields.

The PA–HPEI–OACF constructed with PA, HPEI, and ACF displays excellent performance in the adsorption and separation of In(iii).

The stability of Au nanoparticles (AuNPs) is easily affected by environmental factors, and the use of expensive disposable AuNP-based probes not only wastes resources but also increases the cost of detection. Therefore, there is an urgent need to develop stable and recyclable AuNP-based probes. Here, highly stable AuNPs were synthesized via an in situ reduction reaction between HAuCl4 and hyperbranched polyethylenimine (HPEI). We used HPEI to replace the small molecule reducing agent as a green reducer and template for the green and facile preparation of AuNPs as well as a good stabilizer and decorator of AuNPs. Due to the good properties (massive amount of amino groups, excellent reduction ability and hyperbranched topology structure) of HPEI, the HPEI–AuNPs are highly stable under high temperatures, strong ionic strength and different pH conditions. Meanwhile, the reductive HPEI was also used as the reducing agent to reduce Ag+ to Ag0; this can combine with AuNPs to form stable Au–Ag core–shell NPs accompanied by a special red-to-brown color change, achieving the colorimetric detection of Ag+ by the naked eye. Moreover, this HPEI–AuNP probe not only exhibits good selectivity and high sensitivity (a LOD of 0.41 μM) towards Ag+ but has also been successfully applied in real water samples (drinking and tap water). More importantly, by taking advantage of an etching reaction of the Ag shell of the Au–Ag core–shell NPs, a recoverable and reusable HPEI–AuNP probe towards Ag+ was developed successfully. This novel colorimetric system shows excellent recyclability and reusability, which is inspirational for the development of low-cost AuNP colorimetric probes and consistent with the idea of green chemistry.

To improve the accuracy and specificity of visual sensors for detecting Cu(II) and Hg(II), a fluorescent and colorimetric dual-modal sensor based on Au nanoparticles (AuNPs) prepared by using carbon dots (CDs) was designed. If a sensor is to be applied for the detection of targets in different environmental backgrounds, it needs to have high stability against heat, pH, and salt. To this end, CD-wrapped AuNP probes were fabricated by the in situ reaction of chloroauric acid and reductive CDs. The reductive CDs were prepared with hyperbranched polyethyleneimine (HPEI) as a carbon source. HPEI-CDs not only acted as a reducing agent but also as an excellent stabilizer in the preparation and detection application of the AuNPs. Based on multiple signal responses, including color, UV-Vis absorption, and fluorescence intensity, the HPEI-CD/AuNP nanosensor was used to realize the detection of Cu

In this work, two hyperbranched polyethyleneimine (HPEI) based gels were prepared and employed as adsorbents for the removal of dyes. HPEI-MBA gel was obtained by a cross-linking reaction between HPEI and N, N′-methylene-bis-acrylamide (MBA). And HPEI-MBA gel was further treated with isobutyric anhydride to form thermoresponsive HPEI-MBA-IBAm gel having important application in aspect of desorption of dyes. The structure and morphology of gels were characterized by FTIR, XPS, SEM and BET. Many different affecting factors for adsorption capacity of gel, such as contact time, pH, concentration of dyes and adsorptive selectivity, were investigated. The HPEI-MBA gel demonstrated a satisfactory adsorption capacity for methyl orange (MO) and xylenol orange (XO) as high as 1552.76 mg/g and 3312.06 mg/g, respectively. Interestingly, the HPEI-MBA gels had a considerable adsorption capacity for mixed system of anionic and cationic dyes by regulating the value of pH. In the MO/methylene blue (MB) mixture system, the adsorption capacities of gels for MO and MB were all higher than that of single-dye system, and in the MO/basic fuchsin (BF) mixture, the adsorption capacity for MO and BF can be improved under neutral condition. In the MO adsorption process, the adsorption/desorption kinetic of HPEI-MBA and HPEI-MBA-IBAm gels exhibited a good fit to the pseudo-second-order model. Meaningfully, the adsorption efficiency of HPEI-MBA gel for MO was still as high as 93.52% after 11 cycles of adsorption/desorption. More importantly, we developed a general and facile method to achieve dye desorption by adjusting temperature which relies on the temperature-sensitive properties of HPEI-MBA-IBAm. Therefore, the HPEI-MBA gels and HPEI-MBA-IBAm gels, as a new recycle adsorbent, could have comprehensive application in the removal of dyes from wastewater.

Many colorimetric sensors based on noble metal nanoparticles for the detection of mercury ion (Hg2+) have attracted widespread interest from academia in recent years. A critical issue is how to realize the detection of Hg2+ with high sensitivity and selectivity. A novel colorimetric sensor based on AgNPs stabilized by linear thermoresponsive poly(N-isopropyl acrylamide) (PNIPAm) was developed for the application of detecting Hg2+ with a color change from yellow to taupe brown due to the formation of Ag–Hg core–shell nanoparticles. The AgNP/PNIPAm sensor exhibited good selectivity and high sensitivity (LOD = 75 nM) with a good linear relationship not only in the ultrapure water (R2 = 0.9903) but also in the tap water (R2 = 0.9905). More importantly, based on the thermosensitivity of PNIPAm, this sensor could also achieve the separation of Ag–Hg composites with enriching efficiencies of 97.60% and 95.40% for Ag and Hg, respectively, which can avoid serious secondary pollution. Therefore, this dual-functional nanocomposite has important potential implications in the detection and separation of Hg2+.

In this paper, temperature and pH dual-sensitive supramolecular micelles were constructed from star polymer β-cyclodextrin-poly(N-isopropylacrylamide) (β-CD-PNIPAM) and benzimidazole terminated poly(ε-caprolactone) (BM-PCL). The supramolecular micelles were formed based on the reversible host-guest recognition between β-CD and BM. The size of supramolecular micelles was about 50-100 nm and the LCST was about 30.5 ℃. The drug loading efficiency of supramolecular micelles for DOX was high due to the hydrophobic micelles core of PCL and hydrophobic cavity of β-CD. The release of drugs from supramolecular micelles was suppressed at neutral solution and room temperature but accelerated at acidic solution and 37 ℃. The drug loaded supramolecular micelles exhibited higher anti-cancer activity than free drugs. These temperature and pH dual-sensitive supramolecular micelles might possess potential applications for anticancer drug delivery.

In this paper, the primary amine extractant (N1923) was modified by phytic acid (PA), and then a novel solvent impregnated resins (SIRs) were prepared using PA modified N1923 as the extractant and styrene-divinylbenzene type macroreticular resin (HZ–803) as the support. Adsorption performance and adsorption mechanism of SIRs for In (III) was studied from hydrochloric acid medium. The SIRs were characterized by FTIR, SEM, BET, TGA and XPS. The effect of mass fraction of PA, solution pH, adsorbent dosage, adsorption time, initial concentration of In(III) and adsorption temperature on adsorption was investigated. The adsorption capacity of SIRs for In(III) was enhanced by PA modified N1923. When the mass fraction of PA was 33.3%, SIRs have the highest adsorption capacity at pH of 3.13. The adsorption process can be well described by the pseudo second-order model and Langmuir isotherm model, and the adsorption of In(III) on SIRs is endothermic process. The FTIR and XPS spectra of SIRs before and after adsorption indicate that the amine group and the phosphate group are the functional groups for adsorption of In(III). In addition, the adsorption selectivity of SIRs for In(III) was also investigated at different pH. The SIRs can preferential adsorb In(III) in two components system (In(III)/Cu(II), In(III)/Zn(II), In(III)/Fe(II)) and quaternary components system (In(III)/Cu(II)/Fe(II)/Zn(II)).

Branched AuNPs usually have two or more local surface plasmon resonance (LSPR) absorption bands due to their structural anisotropy, and the LSPR performance is more sensitive to the changes of environmental refractive index than that of spherical AuNPs. The design and preparation of branched AuNPs as colorimetric probes is expected to improve the selectivity and sensitivity of detection of targets. In this paper, branched AuNPs were innovatively synthesized via hyperbranched polyethylenimine (HPEI) fabricated and capped AuNPs as seeds and cetyltrimethylammonium bromide (CTAB) as template agent. The branched AuNPs were characterized by TEM, DLS, zeta potentials and UV-Vis spectra. Using the branched AuNPs as colorimetric probe, the detection system for Hg2+ and Ag+ showed bright color changes from blue to orange and blue to green based on the morphological evolution of branched AuNPs. The branched AuNPs could selectively detect Hg2+ and Ag+ at concentrations as low as 77 and 140 nM, respectively. Moreover, this unusual colorimetric method has been successfully used in real water samples and has great potential as a simple, rapid, sensitive and selective method for the detection of Hg2+ and Ag+.

A new colorimetric method of detecting Hg2+ in aqueous solutions was proposed, based on the three color changes of gold nanoparticles (AuNPs) with the assistance of ascorbic acid (AA) and multi-sulfhydryl functionalized hyperbranched polyethylenimine (SH-HPEI). The mechanism of sensing is based on the formation of Au-Hg alloy and its aggregation, along with the corresponding three color changes from red (AuNPs) through sandy beige (Au-Hg alloy) to celandine green (larger Au-Hg alloy). Compared with usual colorimetric assays with only one color change progress from red to blue or red to purple of reported AuNPs, this assay is highly selective for Hg2+ detection due to the fact that the appearing probability of identical three color changes triggered by interfering agents or the possibility of false positive results is very, very low. The detection limit of 8.76 × 10−9 M is lower than the guideline value of Hg2+ (30 nM) in drinking water defined by the World Health Organization (WHO). Meanwhile, the concentration range (from 8.76 × 10−9 to 1.27 × 10−4 M) of this new detection method is the widest one that has been reported. Moreover, this method is successfully applied to detecting Hg2+ in real water sample. More importantly, this novel colorimetric sensor based on multiple color changes may open a new avenue for the development of Hg2+ sensing probes.

The hyperbranched polyethylenimine (HPEI) derivative with thiol (SH) terminals was synthesized and used as multidentate ligand to stabilize AuNPs/analyte composites. A facile and rapid colorimetric method for the sensitive and selective detection of Ag+ based on the formation of Au-Ag core-shell NPs with three color changes (red through brown to green) was developed. Successive multiple color changes can greatly improve the specificity and selectivity of this colorimetric sensor owing to the lower possibility of false positive results. Other environmentally relevant metal ions did not interfere with the determination of Ag+. The response (i.e., the absorbance at 600 nm, A600 nm) was linearly proportional to the Ag+ concentration in a range from 8.76 × 10−9 to 1.27 × 10−4 M with a detection limit of 8.76 × 10−8 M by the naked eyes and 8.76 × 10−9 M by the UV–vis spectra. For the first time, this novel colorimetric sensor based on multiple color changes was developed and successfully applied to detect Ag+ in real samples.

In this paper, sensitive polymeric hollow spheres self-assembled from chitosan-grafted-β-cyclodextrin (CS- g -CD) and sodium tripolyphosphate (TPP) were prepared for controlled release of doxorubicin (DOX). The assemblies were formed by electrostatic interactions between positively charged amino group in CS- g -CD and negatively charged phosphate in TPP. The hollow spheres with diameters about 100 nm were confirmed by transmission electron microscopy (TEM) and laser particle analyzer. The microspheres with hollow cavity were beneficial to improve the drug loading capacity for DOX with entrapment efficiency above 60%. The cumulative release of DOX from CS-g-CD/TPP hollow microspheres increased with the decrease of pH and the increase of temperature or ionic strength. At 37 °C and pH 5.2, the maximum drug release was above 90% with a continuous release rate. In-vitro cytotoxicity tests indicate that drug loaded hollow spheres exhibited evidently inhibition against cancer cells. These sensitive polymeric hollow spheres are expected to be used in biomedical field as potential carrier.

A novel solvent-impregnated resin (SIR) with trialkylphosphate Cyanex 923 as extractants and macroporous resin HZ830 as substrate was prepared to adsorb In(III) from HCl solutions. The effects of HCl concentration on adsorption were investigated within the range of 0.5 to 7 mol L− 1, and results showed that adsorption capacity was greatest at 2 mol L− 1 HCl. The adsorption mechanism of In(III) in chloride medium suggested that In(III) was apt to be adsorbed as a neutral species InCl3. As the anionic species InCl4− it tended to be adsorbed in the form of ion pairs combined with protons. The extraction stoichiometry of In (III) with SIR was studied, and the extracted species were found to be InCl3·nL and HInCl4·nL (n = 2, 3). The isothermal adsorption of In(III) fit the Langmuir model. Kinetic data indicated that the adsorption process was consistent with a pseudo second order model, and the sorption rate was mainly controlled by an intraparticle diffusion step. A column experiment showed that In(III) could be eluted from SIR with 2 mol L− 1 sulfuric acid, and the SIR showed good stability and reusability after five adsorption-elution cycles. When the SIR was applied for In(III) adsorption from waste liquid crystal display (LCD) leaching solution containing 102.15 mg L− 1 In(III), the adsorption efficiency exceeded 90% with 0.30 g adsorbent.

A colorimetric sensor, based on the synergistic coordination effect on a gold nanoparticle (AuNP) platform has been developed for the determination of creatinine. The sensor selects citrate stabilized AuNPs as a platform, polyethylene glycol (PEG) as a decorator, and Hg2+ as a linkage to form a colorimetric probe system (PEG/Hg2&minus, &ndash, AuNPs). By forming hydrogen bond between the oxygen-containing functional groups of PEG and citrate ions on the surface of AuNPs, this probe shows good stability. PEG coordinated with Hg2+ synergistically and specifically on the surface of dispersed AuNPs, and the existence of creatinine could induce the aggregation of AuNPs with a corresponding color change and an obvious absorption peak shift within 5 min. This PEG/Hg2+&ndash, AuNPs probe towards creatinine shows high sensitivity, and a good linear relationship (R2 = 0.9948) was obtained between A620&ndash, 522 nm and creatinine concentration, which can achieve the quantitative calculations of creatinine. The limit of detection (LOD) of this PEG/Hg2+&ndash, AuNPs probe was estimated to be 9.68 nM, lower than that of many other reported methods (Supplementary Materials Table S3). Importantly, the sensitive probe can be successfully applied in a urine simulating fluid sample and a bovine serum sample. The unique synergistic coordination sensing mechanism applied in the designation of this probe further improves its high selectivity and specificity for the detection of creatinine. Thus, the proposed probe may give new inspirations for colorimetric detection of creatinine and other biomolecules.

Temperature and H

Three GO-HPEI gels were prepared by a cross-linking reaction of graphene oxide (GO) with hyperbranched polyethylenimines (HPEIs) with different molecular weight. The GO-HPEI gels are different from the most reported GO-based materials and have superior adsorption performance because that these gels have more adsorption sites over using the common cross-linking agent (especially double-functionality or tri-functionality monomer). The morphology and structure of the GO-HPEI gels were characterized by FTIR, XRD, SEM, TEM, BET, TGA and elemental analyses. The adsorption property of Pb(II) onto GO-HPEI gels and the factors that influence the adsorption, such as the Pb(II) concentration, contact time and pH value, were investigated. The GO-HPEI gel exhibited an adsorption capacity as high as 438.6 mg g −1 for Pb(II) ions, and its insolubility in water makes the separation from wastewater easy. Adsorption experiments demonstrated that the amino groups and the cross-link density affect the adsorption capacity. In the Pb(II) adsorption process, the adsorption kinetic and equilibrium data were well simulated with the pseudo-second-order and Langmuir isotherm models. The adsorption capacity of the GO-HPEI gel for Pb 2+ only exhibited a slight decrease after eight cycles of adsorption/desorption, indicating its good stability. Therefore, the GO-HPEI gels could serve as promising adsorbents for potential application in the removal of Pb(II) from wastewater.

The development of a green and facile strategy for synthesizing high stable gold nanoparticles (AuNPs) is still highly challenging. Additionally, the main problems regarding AuNPs based colorimetric sensors are their poor selectivity and low sensitivity, as well their tendency to aggregate during their synthesis and sensing process. Herein, we present an in-situ reduction strategy to synthesize thermoresponsive hyperbranched polymer (i.e., Hyperbranched polyethylenimine-terminal isobutyramide (HPEI-IBAm)) functionalized AuNPs. The HPEI-IBAm-AuNPs show excellent thermal stability up to 200 °C, high tolerance of a wide range of pH value (3–13), and high salt resistance. HPEI-IBAm acted as the template, the reducing agent, and the stabilizing agent for the preparation of AuNPs. The HPEI-IBAm-AuNPs can be used as colorimetric sensors for the detection of Ag+. In the detecting process, HPEI-IBAm serves as a trigger agent to cause an unusual color change from red to brown. This new non-aggregation-based colorimetric sensor showed high stability (maintaining the color lasting without fading), high selectivity, and high sensitivity with an extremely low detection limit of 7.22 nM and a good linear relationship in a wide concentration range of 0–2.0 mM (R2 = 0.9921). Significantly, based on the thermoresponsive property of the HPEI-IBAm, the AuNPs/Ag composites can be separated after sensing detection, which can avoid secondary pollutions. Therefore, the green preparation and the applications of the unusual colorimetric sensor truly embody the concepts of energy saving, environmental protection, and sustainable development.

In this paper, hybrid vesicles assembled from hydrophilic graft copolymer sodium alginate-g-poly(N-isopropylacrylamide) (ALG-g-PNIPAM) and multivalent metal ions (Ca2+ and Al3+) for controlled release of 5-Fluorouracil (5-FU) were studied. Transmission electron microscopy (TEM) showed that the vesicles had a well-defined hollow structure with a size of about 100 nm. The hydrophobic membrane was formed by the negatively charged sodium alginate cross-linked with metal ions, and the diffuse corona was constituted of swollen neutral polymer chains. The high stability of vesicles was the result of the nature of coordination complex bonds between anionic sodium alginate chains and metal ions. The lower critical solution temperature (LCST) of polymer vesicles was in the region of 37 °C. The drug loading efficiency of hybrid vesicles was high due to the large cavities of hollow structure and intermolecular attractions with drug. Changing temperature, pH or ionic strength, a sustained and controlled drug release was observed. The novel hybrid polymer vesicles are expected to be used in the field of intelligent drug delivery system.

Here we have developed a facile and rapid colorimetric method for the sensitive and selective detection of Ag(+) based on the non-aggregation of gold nanoparticles (Au NPs) capped with hyperbranched polyethylenimine derivatives. In the detection process, an unusual colour change from red to brown was observed due to the formation of Au-Ag core-shell nanoparticles, which was more sensitive than that of the usual colorimetric assays (red to blue) based on the aggregation of Au NPs. After the colour changed, the non-aggregation-based Au-Ag core-shell nanomaterials did not aggregate further and could remain stable for a long time, which was convenient to record, detect and observe. The sensing probe exhibited a drastically long observing time for detecting Ag(+) owing to the stability of the Au-Ag core-shell non-aggregates, high sensitivity with a low detection limit of 8.76 nM by the naked eye and 1.09 nM by using a UV-vis spectrophotometer and a good linear relationship within the range from 1.09 to 109 nM. The colour change of the system is very fast, occurring within 1 to 2 minutes. Moreover, the proposed method also showed a remarkably high selectivity toward Ag(+) and was successfully used in tap water and drinking water samples. Therefore, this unusual colorimetric assay based on the non-aggregation of Au NPs has a great potential as a simple, rapid, sensitive and selective detection method for the detection of Ag(+).

A strategy for enriching, separating and detecting Hg2+ based on thermoresponsive hyperbranched polyethylenimine (HPEI) with isobutyramide (IBAm) end groups (HPEI-IBAm) capped gold nanoparticles (AuNPs) is reported. The thermoresponsive AuNPs can enrich approximately 94.5% of Hg2+ in solution, with higher enriching efficiency than that toward Ni2+, Cu2+, Mn2+, Pb2+ and Cr3+ heavy metal ions. The enriched Hg2+ can be separated by simple stratification or centrifugation. By virtue of the specific amalgam of reduced mercury(II) ions with thermoresponsive HPEI-IBAm capped gold nanoparticles (AuNPs), an unusual color change from red to fawn can be used as a colorimetric probe to detect Hg2+ with a limit of detection (LOD) of 8.8 nM by the naked eye and 1.1 nM by a UV-vis spectrophotometer. Importantly, this colorimetric sensor based on the formation of non-aggregated Au–Hg alloy stabilized by thermoresponsive HPEI-IBAm is more sensitive than that of the usual colorimetric sensors (red to blue) based on aggregation of AuNPs. After the color changed, the Au–Hg alloys did not aggregate further and could remain stable for a long observation time due to the stabilizing effects of HPEI-IBAm, which was convenient to record, detect and observe. The sensing process is very fast with a response time of less than 0.5 minutes. In addition, the proposed method showed an excellent selectivity for Hg2+ and was successfully applied in tap water and drinking water samples. Therefore, this strategy for the first time achieved simultaneous enrichment, separation and detection of Hg2+ based on the thermoresponsive HPEI-IBAm/AuNPs composite, which has the potential application for environmental renovation and groundwater analysis.

A new supramolecular complex, which can be used as a nanocarrier, was formed conveniently by the co-assembly of hyperbranched polyethylenimine (HPEI) with a novel carboxylic acid which has one or two generations of dendrites. The obtained supramolecular complexes consisting of two different dendritic polymeric segments were verified by FTIR, 1H NMR and DLS. After extracting with water or solutions of dyes, the supramolecules can form large aggregates as verified by DLS analysis. These supramolecular aggregates could be used as nanocarriers to efficiently encapsulate polar dyes such as the anionic dyes methyl orange (MO), eosin Y (EY) and fluorescein sodium (FS). This encapsulation behavior of the complexes based on an aggregation mechanism is different from that of the simple inverted micelles and unimolecular transporter systems reported. And the encapsulation capacities of the aggregates could reach a maximal value as the HPEI concentration and the density of the carbon chains increased to a certain value. Besides, the carrier with a dendritic shell could accommodate more guests than the corresponding carriers with only a linear shell, which shows the superiority of the dendritic shell. Meanwhile, an increase of the length of the outer carbon chain in the complex could distinctly improve the encapsulation ability. Therefore, supermolecules with a dendritic shell not only simplify the synthesis approach of covalent polymers, but also maintain a high encapsulation ability for guests, which are attributes worth popularizing.

A well-defined double hydrophilic poly(β-cyclodextrin)-containing diblock copolymer PEG-b-PCD was synthesized by atom transfer radical polymerization (ATRP). Complex micelles with defined core-shell structure were formed based on the host-guest interactions between poly(β-cyclodextrin) block copolymer and benzimidazole modified poly(e-caprolactone) (BM-PCL). The hydrophobic PCD/BM-PCL resided in the core of micelles, while the hydrophilic poly(ethylene glycol) (PEG) chains acted as the micelles shell. The micelles exhibited regular spheres with diameter of about 255nm. The drug loading efficiency of micelles for doxorubicin (DOX) was high due to the hydrophobic core containing poly(β-CD) and PCL. The in vitro release demonstrated that DOX-loaded polymer micelles exhibited an enhanced sustained manner after an initial burst release. The release of drugs was accelerated as the pH reduced from 7.0 to 2.0 and the temperature increased from 25 to 37°C. These results indicate that the complex micelles have potential applications in controlled drug delivery.

In this paper, thermo-sensitive polyelectrolyte complex nanoparticles assembled from chitosan-graft-poly(N-isopropylacrylamide) (CS-g-PNIPAM) and sodium alginate-graft-poly(N-isopropylacrylamide) (SA-g-PNIPAM) were prepared for entrapment and release of 5-fluorouracil (5-FU). The morphology and size of the nanoparticles were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The polyelectrolyte complex nanoparticles showed a narrow size distribution. The hydrogen bonding interactions between nanoparticles and 5-FU, which was determined by fourier-transformed infrared spectroscopy (FTIR), increased drug loading. Glutaraldehyde, as a cross-linking agent, reinforced the nanoparticle structure and decreased the burst drug release. When changing temperature, pH, or ionic strength, a sustained and controlled drug release was observed. The novel complex nanoparticles with environmentally sensitive properties are expected to be useful in the field of intelligent drug delivery system.

A solvent impregnated resin (SIR) with sec-octylphenoxy acetic acid (CA-12) impregnated on a styrene-divinylbenzene copolymer support (HZ818) was first prepared. To improve the stability of the first SIRs for indium adsorption, a novel type of SIR (NSIR) had been prepared by forming a PVA–boric acid protective layer on the first SIR containing CA-12. The NSIR and SIR were characterized, and their adsorption behavior for indium(III) were compared by batch and column methods in a hydrochloric acid medium. Both the NSIR and SIR showed high adsorption capacities for In(III) at pH 3.0, and the maximum adsorption capacities increased with temperature. The Langmuir isotherm and pseudo second-order model fit the experiment data well at different temperatures. The NSIR showed better stability and reusability than the SIR. It is possible to separate In(III) from a mixed solution containing Zn(II), Cu(II), Cd(II) and In(III) at pH 3.0 from hydrochloric acid medium with SIR and NSIR.

Three solvent impregnated resins (SIRs) were first prepared using two types of nonreactive polystyrene-divinylbenzene polymers (HZ818 and HZ830) and one type of reactive weak basic ion exchange resin (D301) as supports and HEHEHP (2-ethylhexyl phosphonic acid mono(2-ethylhexyl) ester) as the extractant. Then the first two prepared SIRs were coated by poly-vinyl alcohol (PVA)-H3BO3 to improve their stability. The two types of coated SIRs were called HZ818-CSIR and HZ830-CSIR, and the third type of SIR was called D301-SIR. The three adsorbents were characterized by scanning electron microscopy and infrared spectrometer. The adsorption properties of iron (III) with three adsorbents were studied by batch method from sulfuric acid medium in the range of pH 0.9–1.9. The optimal pH values of all adsorbents were found at 1.5, and the saturated adsorption capacities of HZ818-CSIR, HZ830-CSIR and D301-SIR were determined as 16.7 mg·g− 1, 15.9 mg·g− 1 and 25.6 mg·g− 1 at 298 K, respectively. The adsorption isotherms were found to be fitted with Langmuir isotherms. The adsorption kinetic behaviors of HZ818-CSIR and HZ830-CSIR were fitted with pseudo-second-order kinetic model, while that of D301-SIR with Lagergren first-order kinetic model. The adsorption mechanisms of the three adsorbents were investigated with methods of saturation, equimolar series change and infrared adsorption spectra. It was found that the adsorption mechanism of Fe(III) with HZ818-CSIR and HZ830-CSIR could be deduced as cation exchange between Fe3 + and H+ from P-OH of HEHEHP accompanied with coordination between Fe(III) ion and the phosphoryl oxygen from HEHEHP. While for the D301-SIR, only a cation exchange between Fe3 + and H+ from P-OH of HEHEHP can be proposed.

A modified solvent impregnated resin (MSIR) was prepared by impregnation of sec-octylphenoxy acetic acid (CA-12) on styrene–divinylbenzene copolymer support (HZ818) after nitration of the benzene rings present in its structure. The MSIRs were characterized by thermogravimetric and Fourier Transform infrared spectroscopy (FTIR) analysis. The adsorption behavior of indium(III) on MSIRs was examined by batch and column method in hydrochloric acid medium. It was shown that optimal pH for indium(III) adsorption was 3.0. The adsorption isotherms were found to follow Langmuir model at different temperatures, and the maximum adsorption capacity enhanced with increasing temperature. The value of enthalpy change was positive, indicating that the adsorption of indium(III) with MSIRs is endothermic. Kinetic data indicated that the adsorption of indium(III) was in a good agreement with the pseudo second-order rate equation. The MSIRs sustained adsorptivity well after three recycles comparing with the SIRs.

Hyperbranched core-shell structure can be constructed by the modification of hyperbranched polyethylenimine (HPEI) with different amide shells. Functionalized HPEI with acetic amide (HPEI-ACAm), propionic amide (HPEI-PRAm), butyric amide (HPEI-BUAm) and isobutyric amide (HPEI-IBAm) shells have been successfully prepared and used as protectors for gold nanoparticles (AuNPs). Novel AuNP composites were obtained through the non-covalent interaction between HPEI-XXAm and gold nanoparticles (XXAm represents ACAm, PRAm, BUAm or IBAm). The resulted AuNP composites can catalyze the reduction reaction of 4-nitrophenol by NaBH4. Interestingly, the catalytic activity of the AuNPs mainly depends on the structure of protectors and the degree of carbon chain arrangement denseness, which should affect the diffusivity of the reactants. In addition, the order of reaction rate is HPEI10K-IBAm0.80 > HPEI10K-ACAm0.80 > HPEI10K-PRAm0.82 > HPEI10K-BUAm0.83. It was found that the increase of the concentrations of the capping HPEI-XXAm polymers can enhance both the reaction rate and the turnover frequency (TOF) values. Furthermore, the reaction rate was accelerated with increasing the reaction temperature for AuNPs-HPEI10K-ACAm0.80 and AuNPs-HPEI10K-PRAm0.82 systems. Interestingly, the reaction rate was accelerated with elevating reaction temperature at the beginning but reached a plateau or decreased sharply for AuNPs-HPEI10K-IBAm0.80 and AuNPs-HPEI10K-BUAm0.82 systems, owing to the thermoresponsivity of the corresponding AuNP composites. As a consequence, the catalytic activity could be controlled by adjusting the different shells of the hyperbranched polyethylenimine.

In this paper, thermo-sensitive polymeric hollow spheres assembled from sodium alginate-graft-poly(N-isopropylacrylamide) (ALG-g-PNIPAM) and β-cyclodextrin (β-CD) were prepared for controlled release of 5-fluorouracil (5-FU). In aqueous solutions, β-CD and PNIPAM formed rod-like segments through inclusion complexation interactions and sodium alginate acted as coil segments, which resulted in the formation of hollow structures. The size and wall thickness of assemblies increased with the increase of β-CD in mixtures. The lower critical solution temperature (LCST) of hollow spheres varied in the range of 35-37°C. The hollow spheres exhibited high drug loading efficiency for 5-FU due to the hydrophilic cavities. The initial composition of mixtures, temperature and pH had a significant effect on the inclusion ability and drug release. Increasing temperatures above the LCST or decreasing pH to acidic conditions, a more rapid release rate was observed.