Interfacial contact barrier and charge carrier transport of MoS2/metal(001) heterostructures.

The rapid rise of two-dimensional (2D) materials has aroused increasing interest in the fields of microelectronics and optoelectronics; various types of 2D van der Waals heterostructures (vdWHs), especially those based on MoS2, have been widely investigated in theory and experiment. However, the interfacial properties of MoS2 and the uncommon crystal surface of traditional three-dimensional (3D) metals are yet to be explored. In this paper, we studied heterostructures composed of MoS2 and metal(001) slabs, based on the first-principles calculations, and we uncovered that MoS2/Au(001) and MoS2/Ag(001) vdWHs reveal Schottky contacts, and MoS2/Cu(001) belongs to Ohmic contact and possesses ultrahigh electron tunneling probability at the equilibrium distance. Thus, the MoS2/Cu(001) heterostructure exhibits the best contact performance. Further investigations demonstrate that external longitudinal strain can modulate interfacial contact to engineer the Schottky-Ohmic contact transition and regulate interfacial charge transport. We believe that it is a general strategy to exploit longitudinal strain to improve interfacial contact performance to design and fabricate a multifunctional MoS2-based electronic device.

Improving identification of molecularly imprinted monolith to benzoylation modified peptides by a deep eutectic solvents monomer-induced cooperation.

In this study, a strategy of improving imprinting performance was developed using an enhanced cooperation effect of functional monomers based on deep eutectic solvents (DESs) monomer for the specific enrichment of benzoylation modified peptides. Zinc acrylate and DESs monomers were used as binary functional monomers, and ethylene glycol dimethacrylate was used as the cross-linking agent with SGRGKbz as template to prepare an imprinted monolith. It was observed that the use of DESs monomer significantly improveed the affinity of benzoylation imprinted monolith and increased the adsorption capacity. Under optimal conditions, the recovery and imprinting factor (IF) of the imprinted monolith for SGRGKbz can reach 93.0% and 10.58, respectively. The average recovery of SGRGKbz extracted from the spiked histone digestion solution can reach 88.4% (n = 5, RSD = 3.4%). After treatment with the benzoylation imprinted monolith, 12 benzoylation modified peptides, 13 benzoylation modified sites and 12 benzoylation proteins could be identified in the digestion of mouse liver protein, while only one of each benzoylation modified peptide, benzoylation modified site and benzoylation protein could be identified in the untreated digestion of mouse liver protein. The results indicated that the prepared imprinted monolith using DESs-based functional monomer was an effective method to increase the affinity of the resulting MIP.

Dual-function monolithic enzyme reactor based on dopamine/graphene oxide coating for simultaneous protein enzymatic hydrolysis and glycopeptide enrichment.

A new dual-function enzyme reactor was prepared based on a dopamine/graphene oxide coated boron affinity monolithic column, which can be used for simultaneous protein enzymatic hydrolysis and glycopeptide enrichment. Firstly, a boron affinity monolithic column was prepared as the carrier for enzyme reactor. Secondly, the monolithic column was coated with dopamine/graphene oxide to provide higher specific surface area for the increase in the amount of trypsin bound. Then, dopamine can self-polymerize under alkaline conditions to produce multiple reaction sites. By the Schiff base reaction and Michael addition reaction with amino, sulfhydryl groups to trypsin, enzyme were immobilized on the boron affinity monolithic carrier. The enzyme activity was characterized by kinetic parameters maximum rate (Vmax) of the enzyme reaction and Michaelis constant (Km). Km of the dual-function enzyme reactors doped with PDA/GO and without PDA/GO were 34.37 and 120.93 mM, Vmax were 1.35 and 3.35 mM/min, respectively. The performance of the dual-function enzyme reactor was evaluated by protein extraction of mouse liver. After digested by the dual-function enzyme reactor, the number of peptides was 4,801, which was 960 more than the number of peptides in the solution digestion. At the same time, the dual-function enzyme reactor displayed the ability to capture cis-dihydroxy compounds specificly. A total of 55 glycopeptides were enriched in the dual-functional enzyme reactor, corresponding to 33 glycoproteins. The dual-function enzyme reactor provided repeatable performance and robust with long-term storage.

Improving sorption performance of a molecularly imprinted monolithic column by doping mesoporous molecular sieve SBA-15.

For the first time a hybrid molecularly imprinted polymer (MIP) doped with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS)-modified mesoporous molecular sieve SBA-15 for target peptide recognition has been developed. Zinc acrylate and methacrylic acid were used as binary functional monomers, and ethylene dimethacrylate was used as cross-linking agent to prepare an imprinted monolith against Val-Tyr-Ala-Leu-Lys(glutarylation) (VYALKglu). The morphology of the polymers was characterized by scanning electron microscopy, FT-IR spectroscopy, energy dispersive spectroscopy, and 1H NMR. The SBA-15-MPS MIP showed high recovery of 87.1% and the IF of 12.9 for the enrichment of the template peptide. When the template peptide concentration ranged from 5 to 90 µg mL-1, the correlation coefficients (R2) for the calibration function obtained was better 0.999. The limit of detection (LOD, 0.30 µg mL-1) and limit of quantification (LOQ, 1.0 µg mL-1) were achieved for signal-to-noise ratios of 3:1 and 10:1, respectively. When other kinds of synthetic peptides were used as analogs, the selectivity of the SBA-15-MPS MIP was much better than the SBA-15-MPS NIP (without template peptides) with relative selectivity coefficients of 52.8-265. In contrast, little quinolones and biogenic amines are adsorbed with the SBA-15-MPS MIP. The SBA-15-MPS MIP could enrich VYALKglu from spiked histone digestion with the average recovery of 87.8% and the relative standard deviation (RSD) of 0.99%. As a conclusion, doping of SBA-15 is an effective approach to the improvement of performance of molecularly imprinted monolith.

Improving the Identification of Lysine-Acetylated Peptides Using a Molecularly Imprinted Monolith Prepared by a Deep Eutectic Solvent Monomer.

To overcome the identification challenge of low-abundance lysine acetylation (Kac), a novel approach based on a molecularly imprinted polymer (MIP) was developed to improve the extraction capacity of Kac peptides in real samples. Green deep eutectic solvents (DESs) were introduced and used as one of the synergistic functional monomers with zinc acrylate (ZnA). Glycine-glycine-alanine-lysine(ac)-arginine (GGAKacR) was chosen as a template and N,N'-methylenbisacrylamide (MBAA) was used as a cross-linker. The obtained GGAKacR-MIP had excellent selectivity for the template with an imprinting factor (IF) of up to 21.4. The histone digest addition experiment demonstrated that GGAKacR-MIP could successfully extract GGAKacR from a complex sample. Finally, the application to the extraction of Kac peptides from mouse liver protein digestion was studied in detail. The number of Kac peptides and Kac proteins identified was 130 and 110, which were 3.71-fold and 3.93-fold higher than those of the untreated sample. In addition, the number of peptides and proteins identified after treatment increased from 5535 and 1092 to 17 149 and 4037 (3.10-fold and 3.70-fold, respectively). The results showed that the obtained MIP may provide an effective technical tool for the identification of Kac-modification and peptide fractionation, as well as a potential approach for simultaneously identifying post-translational-modified proteomic and proteomic information.

Origin of macromolecular crowding: Analysis of recognition mechanism of dual-template molecularly imprinted polymers by in silico prediction.

Multi-template imprinting is one of the challenge for molecular imprinting since the selectivity and binding affinity for each analyte decrease significantly compared with the corresponding molecularly imprinting polymers (MIPs) against single template. In this work, molecular crowding effect was tried to remedy the problem of imprinting reduction caused by the competition of two templates. Methacrylic acid (ACR) was used as functional monomer, ethylene dimethacrylate (EDMA) as crosslinker, and polystyrene (PS) as macromolecular crowding agent. With levofloxacin (S-OFX) as the first template, a number of compounds with varied chemical structure were chosen as the second template to investigate the imprinting effect of dual-template. When S-OFX and naproxen (S-NAP) was used as the dual-template, the imprinting factor (IF) of the resulting MIP for S-OFX was 20.1 and IF for S-NAP was 10.9. In contrast, for the single-template MIPs, IF for S-OFX was 22.4, and IF for S-NAP was 11.9. As a comparison, the IF of the DT-MIP prepared in absence of PS was only 2.3 for S-OFX and 1.0 for S-NAP. To analyze recognition mechanism of the molecular crowding-based imprinting system, molecular dynamics simulations to the chain structure of PS and binding modes between template and functional monomers was conducted by NAMD software. All the results displayed that molecular crowding is a promising method to improve the affinity of the dual-template imprinted polymer.

Construction of a microfluidic platform integrating online protein fractionation, denaturation, digestion, and peptide enrichment.

Microfluidic system with multi-functional integration of high-throughput protein/peptide separation ability has great potential for improving the identification capacity of biological samples in proteomics. In this paper, a sample treatment platform was constructed by integrating reversed phase chromatography, immobilized enzyme reactor (IMER) and imprinted monolith through a microfluidic chip to achieve the online proteins fractionation, denaturation, digestion and peptides enrichment. We firstly synthesized a poly-allyl phenoxyacetate (AP) monolith and a lysine-glycine-glycine (KGG) imprinted monolith separately, and investigated in detail their performance in fractionating proteins and extracting KGG from the protein digests of MCF-7 cell. The removal percentage of 94.6% for MCF-7 cell protein and the recovery of 90.8% for KGG were obtained. The number of proteins and peptides identified on this microfluidic platform was 2,004 and 8,797, respectively, which was 2.8-fold and 3.0-fold higher than that of untreatment sample. The time consumed by this platform for a sample treatment was about 9.6 h, less than that of conventional method (approximate 13.3 h). In addition, this platform can enrich some peptide fragments containing KGG based on imprinted monolith, which can be served for the identification of ubiquitin-modified proteomics. The successful construction of this integrated microfluidic platform provides a considerable and efficient technical tool for simultaneous identification of proteomics and post-translational modification proteomics information.

Deep eutectic solvents-based polymer monolith incorporated with titanium dioxide nanotubes for specific recognition of proteins.

An organic-inorganic hybrid monolith incorporated with titanium dioxide nanotubes (TNTs) and hydrophilic deep eutectic solvents (DESs) was prepared and evaluated by the isolation of proteins using solid phase microextraction. A typical polymerization system was composed of choline chloride/methacrylic acid (ChCl/MAA, DESs monomer), glycidyl methacrylate (GMA), as well as ethylene glycol dimethacrylate (EDMA) in the presence of TNTs. Then the epoxy groups on the surface of the resulting monolith were modified with amino groups. The synergistic effect of TNTs and DESs monomer to improve the enrichment performance of the sorbent significantly was demonstrated. Compared with the corresponding TNTs/DESs-free monolith, the recoveries of BSA and OVA were increased to 98.6% and 92.7% (RSDs < 2.0%), with an improvement of more than 60.0%. With a correlation coefficient of determination (R2) higher than 0.9995, the enrichment factors (EFs) were 21.9-28.3-fold. In addition, the resulting monolith was further applied to specifically capture proteins from rat liver according to their pI value, followed by HPLC-MS/MS analysis. The results indicated that the developed monolith was an effective material to isolate protein species of interest according to the pI value of target proteins.

Molecularly Imprinted Polymers Doped with Carbon Nanotube with Aid of Metal-Organic Gel for Drug Delivery Systems.

PURPOSE: The incidence of breast cancer worldwide has been on the rise since the late 1970s, and it has become a common tumor that threatens women's health. Aminoglutethimide (AG) is a common treatment of breast cancer. However, current treatments require frequent dosing that results in unstable plasma concentration and low bioavailability, risking serious adverse reactions. Our goal was to develop a molecularly imprinted polymer (MIP) based delivery system to control the release of AG and demonstrate the availability of this drug delivery system (DDS), which was doped with carbon nanotube with aid of metal-organic gel. METHODS: Preparation of MIP was optimized by key factors including composition of formula, ratio of monomers and drug loading concentration. RESULTS: By using multi-walled carbon nanotubes (MWCNT) and metal-organic gels (MOGs), MIP doubled the specific surface area, pore volume tripled and the IF was 1.6 times than the reference. Compared with commercial tablets, the relative bioavailability was 143.3% and a more stable release appeared. CONCLUSIONS: The results highlight the influence of MWCNT and MOGs on MIP, which has great potential as a DDS.

Preparation, characterization, and application of soluble liquid crystalline molecularly imprinted polymer in electrochemical sensor.

A novel soluble molecularly imprinted polymer (SMIP) without chemical cross-linker was successfully synthesized. The quinine (QN), which the structure was similar to the template, was chosen as the immobile template to improve the affinity of MIP. 4-Methyl phenyl dicyclohexyl ethylene (MPDE) was used as the liquid crystal (LC) monomer to increase the rigid of the composite. The cooperative effect of QN and MPDE was demonstrated by comparing with the conventional MIP, which synthesized without QN and MPDE. The polymerization conditions of SMIP including the ratio of MAA to MPDE, template to functional monomer, and HQN to QN were also optimized. Moreover, the characterizations of the SMIP were investigated by the transmission electron microscopy (TEM), field emission scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and nitrogen adsorption. In binding behavior, the SMIP presented the maximum adsorption capacity (0.37 ± 0.06 mmol/g) and imprinting factor (3.44 ± 0.25). And above all, the obtained polymer exhibited the solubility in the organic solution. In addition, the proposed SMIP as the electrochemical sensor exhibited a significant conductivity and sensitivity with the detection limit of 0.33 µM for HQN, the recoveries for the sample analysis varied from 97.4 to 100.8%, and the intra-day precision and inter-day precision were within 5.5% and 12.5%, respectively. It turned out that the SMIP had demonstrated more excellent potential than the traditional insoluble MIP in the development of the membrane-based electrochemical sensors.Graphical abstract.

Cooperation effect of 4-vinylbenzeneboronic acid/methacrylic acid on affinity of capecitabine imprinted polymer for drug carrier.

Cooperation effect of 4-vinylbenzeneboronic acid (4-VPBA) and methacrylic acid (MAA) was first used to improve the affinity of molecularly imprinted polymer (MIP) for drug delivery. The MIP was prepared using capecitabine (CAP) as template, MAA as functional monomer, 4-VPBA as auxiliary monomer, and trimethylolpropane trimethacrylate as cross-linker. The preparation conditions of the MIPs were optimized by investigating the types of functional monomers, the types of cross-linkers, the ratio of MAA to 4-VPBA, and the ratio of crosslinker to monomer. The results showed that the as-prepared MIP had the maximum imprinting factor of 4.03, which revealed this material had a specific recognition effect on the template molecules. Experiments with in vitro release indicated that the imprinted material released CAP stably for more than 10 h, while the non-imprinted polymer (NIP) released CAP only 4 h. In addition, the pharmacokinetics results from rats showed that the MIP was significantly superior to the NIP and CAP commercial drugs, and the plasma concentration of CAP reached the plateau between 3.0 and 9.0 h. These findings may extend the applicability of noncovalent molecular imprinting, particularly to the cases where the target molecule containing a cis-dihydroxy structure.

Preparation of gold nanorod-incorporated monolith for solid phase extraction of polycyclic aromatic hydrocarbons.

An organic-inorganic hybrid monolithic column doped with gold nanorods (AuNRs) was prepared and evaluated for solid phase extraction (SPE) of polycyclic aromatic hydrocarbons (PAHs). Excellent dispersibility of AuNRs in binary green porogen system consisting of 1-hexyl-3-methylimidazolium tetrafluoroborate and deep eutectic solvents (DESs) was confirmed by energy dispersive spectrometry (EDS). The particle size of the resulting AuNRs (70-90 nm) was thoroughly examined by a transmission electron microscopy (TEM). The redox system including ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) was used to initiate in situ polymerization at 4 °C to prepare the hybrid monolith. The mesoporous structure of the AuNR hybrid monoliths was confirmed by scanning electron microscopy (SEM) and nitrogen adsorption. With enrichment factors (EFs) of 150- to 292-fold, the developed method was successfully applied to the determination of 10 PAHs in wastewater samples. The recoveries at a spiked level were in the range 84.9 to 99.5% with limit of detections (LODs) and relative standard deviations (RSDs) ranging from 0.02 to 0.10 µg L-1 and 1.5 to 4.2%, respectively. The correlation coefficients (R2) for the calibration function obtained were better 0.9991 for the target compounds. Compared to the AuNR-free monolith, the extraction efficiency of the AuNR-incorporated monolith is more than two times higher. The results indicated that the doping of AuNRs is an effective approach to obtain the hybrid monolithic column with good separation ability for PAHs. Graphical abstract.

Green synthesis of monolithic enzyme microreactor based on thiol-ene click reaction for enzymatic hydrolysis of protein.

In this study, a monolithic enzyme reactor based on a strategy of green synthesis was successfully prepared in a capillary with trypsin immobilized by "thiol-ene" click reaction. A polymer of poly(butyl methacrylate-co-α-methacrylic acid-co-ethylene glycol dimethacrylate) was prepared in a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate and choline chloride/ethylene glycol as the support of enzyme reactor. After "thiol-ene" reaction was used for enzyme immobilization, the Michaelis constants and maximum reaction rate of the resulting immobilized enzyme reactors (IMER) were determined by capillary electrophoresis to be 2.1 mmol/L and 0.028 µmol/min, respectively. The enzymatic hydrolysis of the enzyme reactor under different experimental conditions were investigated. A on-line digestion of bovine serum albumin (BSA) on the new IMER can be achieved within 50 s, up to 864 times faster than in-solution digestion (12 h). BSA can be well digested and the numbers of identified peptides were 73 with the coverage rates of 82.7%. The IMER was further used for the analysis of protein extracts from rat liver, and 1034 protein groups were identified. All these results demonstrated that such a click reaction based IMER would be of great prospect in the high throughput analysis for proteome with high confidence.

Preparation of graphene oxide incorporated monolithic chip based on deep eutectic solvents for solid phase extraction.

A monolithic chip incorporated with graphene oxide (GO) based on deep eutectic solvents (DESs) was developed for solid phase extraction (SPE). The carboxylated GO was modified with p-aminostyrene (pAS) by amidation, and the obtained GO (pAS-COOH-GO) was covalently incorporated into poly(butyl methacrylate-co-ethylene glycol dimethyl methacrylate) monolithic chip. Due to the high viscosity characteristics of DESs, a uniform pAS-COOH-GO incorporated monolithic chip with good permeability can be achieved. A systematic study of the preparation parameters on the performance of the resulting monolith was carried out, including the content of pAS-COOH-GO, DESs composition and porogen ratio. The resulting pAS-COOH-GO incorporated monolith was characterized by nitrogen adsorption, scanning electron microscopy, and transmission electron microscopy. The GO-doped monolithic chip can be used for SPE of polycyclic aromatic hydrocarbons (phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, benzo(a) pyrene, dibenzo(a,h)anthracene and inden(1,2,3,-cd)pyrene). The recoveries were all higher than 90%, which was about twice as high as that of the monolithic chip prepared without GO. By comparing the SPE results with that of GO free monolithic chip, good enrichment effects were demonstrated on the pAS-COOH-GO incorporated monolithic chip.

Synergistic effect of organic-inorganic hybrid monomer and polyhedral oligomeric silsesquioxanes in a boronate affinity monolithic capillary/chip for enrichment of glycoproteins.

A boronate affinity monolith with improved affinity and selectivity for glycoproteins was prepared starting from two monomers. The first is 3-aminopropyltriethoxysilane-methacrylic acid (APTES-MAA), and the other is a polyhedral oligomeric silsesquioxane (POSS) monomer. In the next step, 3-(acrylamido)benzeneboronic acid was adopted as boronate affinity ligand, and ethylene glycol dimethacrylate as the crosslinker, and iso-propanol and octanol as binary porogens. The synergistic effect of APTES-MAA and POSS warrants good affinity and selectivity for glycoproteins, which results in a number of attractive features including (a) a wide operation pH range (from 5 to 8); (b) higher enrichment factors ranging from 19.3 to 20.6; (c) greater recoveries of glycoproteins between 95.8 and 107.1%; (d) lower relative standard deviations of ≤4.2%. Compared to the corresponding APTES-MAA/POSS-free monolith, the new boronate material had 1.7-fold increased glycoprotein recovery from complex samples. Glycoproteins in 500-fold diluted serum samples can be enriched by the boronate monolith. Graphical abstractSchematic representation of the preparation of 3-aminopropyltriethoxysilane-methacrylic acid/polyhedral oligomeric silsesquioxanes boronate affinity monolith. This sorbent exhibits high selectivity and wide pH operation range for capturing glycopeptides.

Improving affinity of imprinted monolithic polymer prepared in deep eutectic solvent by metallic pivot.

One of the major drawbacks of conventional molecularly imprinted polymers (MIPs) is the requirements of volatility porogenic solvent during polymerization. To overcome the default, MIP based on deep eutectic solvent (DES, a new type of green designer solvents) has been synthesized successfully. To improve the affinity of the MIP based on DES, in this work, a strategy of metallic pivot was suggested in the first time to prepare a highly selective MIP monolithic column. A cetirizine-imprinted polymer was prepared in a DES-based porogen system composed of choline chloride/ ethylene glycol (ChCl-EG) in the presence of Co(Ac)2 as metallic pivot. The resulting DES- Co2+-MIP monolith had 23.5 times higher imprinting factor than the Co2+-free MIP monolith. The characterization of polymers indicated that DES was one of the primary factor influencing the MIP morphology and pore structure. Compared with previous metal-mediated and ionic liquid-based imprinted polymers, the introduction of DES as a porogen in polymerization led to higher imprinting factor (approximately 2.9 - 17.1 times). In addition, the resulting DES-Co2+-MIP can be used as an adsorbent for extraction of cetirizine from ethanol solution with the recoveries of 97.8%. As a conclusion, the metallic pivot is a rather valuable strategy for the synthesis of DES-based MIP monolith with high selectivity.

Investigation of deep eutectic solvents as additives to ß-CD for enantiomeric separations of Zopiclone, Salbutamol, and Amlodipine by CE.

The enantioseparation of chiral drugs via CE was first investigated using ß-CD as chiral additive and deep eutectic solvents (DESs) as auxiliary additive. The results showed that improved separation of tested chiral drugs was obtained in the presence of DESs and ß-CD compared to the single ß-CD separation system. With the optimized condition, resolutions of DESs applied ß-CD separation system for rac-Zopiclone, rac-Salbutamol, and rac-Amlodipine increased 3-4.2 times as single ß-CD separation system. The resolutions reached 4.74, 6.37, and 9.67, respectively. The results demonstrate that DESs are viable additives to CD system in CE for the separation of the chiral drugs.

Cost-effective imprinting to minimize consumption of template in room-temperature ionic liquid for fast purification of chlorogenic acid from the extract of E. ulmoides leaves.

One of the main challenges in large-scale applications of molecularly imprinted polymers (MIPs) is the significant amount of template needed in polymer preparation. A new strategy based on room-temperature ionic liquids (RTILs) was suggested to solve this problem by reducing the amount of template in the polymerization recipe. The MIP was synthesized with a mixture of dimethyl sulfoxide and RTIL (1-butyl-3-methylimidazolium tetrafluoroborate) as porogen, in which chlorogenic acid (CGA) was used as template, 4-vinylpyridine (4-VP) as functional monomer, and ethylene glycol dimethacrylate (EDMA) as cross-linker. The influence of polymerization variables, including CGA concentrations, and the ratio of 4-VP to EDMA on imprinting effect were investigated comprehensively. Moreover, the properties involving the column permeability, the number of binding sites, and the polymer morphology of the CGA-MIP monoliths were studied thoroughly. The MIP monolith had an excellent column permeability (1.53 × 10-13 m2) and allowed an ultra-fast on-line SPE, which dramatically shortens the separation time (< 10 min) and improves the separation efficiency. At high flow velocity (5.0 mL min-1), 50 µL of the extract from Eucommia ulmoides leaves can be loaded directly on the CGA-MIP monoliths and CGA with high purity can be obtained with a recovery of 89.01 ± 0.05%. As a conclusion, the resulting RTIL-induced approach of preparing MIP may be an effective tool in fabricating MIP in a low-cost way. Graphical abstract ᅟ.

Floating molecularly imprinted polymers based on liquid crystalline and polyhedral oligomeric silsesquioxanes for capecitabine sustained release.

Molecularly imprinted polymers (MIPs) have drawn extensive attention as carriers on drug delivery. However, most of MIPs suffer from insufficient drug loading capacity, burst release of drugs and/or low bioavailability. To solve the issues, this study designed an imprinted material with superior floating nature for oral drug delivery system of capecitabine (CAP) rationally. The MIPs was synthesized in the presence of 4-methylphenyl dicyclohexyl ethylene (liquid crystalline, LC) and polyhedral oligomeric silsesquioxanes (POSS) via polymerization reaction. The LC-POSS MIPs had extended release of the template molecules over 13.4 h with entrapment efficiency of 20.53%, diffusion coefficient of 2.83 × 10-11 cm2 s-1, and diffusion exponent of 0.84. Pharmacokinetic studies further revealed the prolong release and high relative bioavailability of CAP in vivo of rats, showing the effective floating effect of the LC-POSS MIPs. The in vivo images revealed visually that the gastroretentive time of the LC-POSS MIPs was longer than non-LC-POSS imprinted polymers. The physical characteristics of the polymers were also characterized by nitrogen adsorption experiment, scanning electron microscopy, thermogravimetric analysis and differential scanning calorimetry analysis. As a conclusion, the LC-POSS MIPs can be used as an eligible CAP carrier and might hold great potential in clinical applications for sustained release drug.

A star-shaped molecularly imprinted polymer derived from polyhedral oligomeric silsesquioxanes with improved site accessibility and capacity for enantiomeric separation via capillary electrochromatography.

A star-shaped molecularly imprinted coating was prepared starting from octavinyl-modified polyhedral oligomeric silsesquioxanes (Ov-POSS). It possesses a relatively open structure and has good site accessibility and a larger capacity even at lower cross-linking. The imprinted coating was prepared from S-amlodipine (S-AML) as the template and analyte, Ov-POSS as the cross-linker, and methacrylic acid as the functional monomer. The preparation and chromatographic parameters were optimized, including ratio of template to functional monomer, apparent cross-linking degree, pH value, ACN content and salt concentration in the mobile phase. The best resolution in enantiomer separation by means of capillary electrochromatography reaches a value of 33. A good recognition ability (α = 2.60) was obtained and the column efficiency for S-AML was 54,000 plates m-1. The use of Ov-POSS as a cross-linker significantly improves the column capacity and thus the detection sensitivity. The results show that Ov-POSS is an effective cross-linker for the preparation of imprinted polymers with good accessibility and large capacity. Graphical abstract Schematic presentation of the preparation of star-shaped imprinted polymer using octavinyl-modified polyhedral oligomeric silsesquioxanes (Ov-POSS) and by using methacrylic acid (MAA) as functional monomer. The best enantiometric resolution (33) for amlodipine (AML) can be achieved in capillary chromatography (CEC).