Bioinspired Adhesive Antibacterial Hydrogel with Self-Healing and On-Demand Removability for Enhanced Full-Thickness Skin Wound Repair.

Adhesive-caused injury is a great threat for extensive full-thickness skin trauma because extra-strong adhesion can incur unbearable pain and exacerbate trauma upon removal. Herein, inspired by the mussel, we designed and fabricated an adhesive antibacterial hydrogel dressing based on dynamic host-guest interaction that enabled on-demand stimuli-triggered removal to effectively care for wounds. In contrast with most hard-to-removable dressing, this adhesive antibacterial hydrogel exhibited strong adhesion property (85 kPa), which could achieve painless and noninvasive on-demand separation within 2 s through a host-guest competition mechanism (amantadine). At the same time, the hydrogel exhibited rapid self-healing properties, and the broken hydrogel could be completely repaired within 5 min. The hydrogel also had excellent protein adsorption properties, mechanical properties, antibacterial properties, and biocompatibility. This on-demand removal was facilitated by the introduction of amantadine as a competitive guest, without any significant adverse effects on cell activity (>90%) or wound healing (98.5%) in vitro. The full-thickness rat-skin defect model and histomorphological evaluation showed that the hydrogel could significantly promote wound healing and reduce scar formation by regulating inflammation, accelerating skin re-epithelialization, and promoting granulation tissue formation. These results indicate that the developed adhesive antibacterial hydrogel offers a promising therapeutic strategy for the healing of extensive full-layer skin injuries.

Association between Neutrophil Levels on Admission and All-Cause Mortality in Geriatric Patients with Hip Fractures: A Prospective Cohort Study of 2,589 Patients.

Objective: To evaluate the association between neutrophil levels and all-cause mortality in geriatric hip fractures. Methods: Elderly patients with hip fractures were screened between January 2015 and September 2019. Demographic and clinical characteristics of the patients were collected. Linear and nonlinear multivariate Cox regression models were used to identify the association between neutrophil levels and mortality. Analyses were performed using Empower Stats and R software. Results: A total of 2,589 patients were included in this study. The mean follow-up period was 38.95 months. During the study period, 875 (33.80%) patients died due to various causes. Linear multivariate Cox regression models showed that neutrophil levels were associated with mortality after adjusting for confounding factors, when neutrophil concentration increased by 1∗109/L, the mortality risk increased by 3% (HR = 1.03, 95% CI: 1.00-1.06, and P=0210). Neutrophil concentration was used as a categorical variable; we only found statistically significant differences when neutrophil levels were high (HR = 1.27, 95% CI:1.05-1.52, and P=0.0122). In addition, the results are stable in P for trend and propensity score matching sensitivity analysis. Conclusions: Neutrophil levels are associated with mortality in geriatric hip fractures and could be considered a predictor of death risk in the long-term. This study is registered with the Chinese Clinical Trial Registry (ChiCTR) as number ChiCTR2200057323.

Solvent effect on the excited-state intramolecular double proton transfer of 1,3-bis(2-pyridylimino)-4,7-dihydroxyisoindole.

Density functional theory (DFT) and time-dependent density functional theory (TDDFT) are used to study the solvatochromic effect and the excited-state intramolecular double proton transfer (ESIDPT) of 1,3-Bis(2-pyridylimino)-4,7-dihydroxyisoindole (BPI-OH) in different kinds of solvents. The hydrogen bonding parameters and IR spectra reveal that in the excited state, the strength of excited hydrogen bond increase with the decrease of solvent polarity. Furthermore, the reduction density gradient (RDG) analysis confirms the corresponding conclusion. Frontier molecular orbitals (FMOs) are analyzed, illuminating that the smaller the polarity of solvent, the smaller the energy gap between the HOMO and LUMO. The structures of BPI-OH (N) (normal), BPI-OH (T1) (single), and BPI-OH (T2) (double) were optimized. Previous reports found the double protons in BPI-OH molecule are transferred step-by-step process BPI-OH(N)→BPI-OH(T1)→BPI-OH(T2) in the ground state (S0) and the first excited singlet state (S1). Here, the potential energy curves of O1-H2 and O4-H5 in the S0 and S1 states were scanned in four kinds of solvents, respectively. It was found that in S1 state, BPI-OH(N)→BPI-OH(T1) was more prone to proton transfer than BPI-OH(T1)→BPI-OH(T2). In addition, by comparing the reaction energy barriers of the four kinds of solvents, it can be found that ESIPT is difficult to occur with the increase of solvent polarity. Meanwhile, it was also studied that MeOH as an explicit solvent was more likely to promote the ESIPT process than other implicit solvents.

Investigating the Influence of Electronic Effects of Functional Groups on the Fluorescence Mechanism of Probes in Water Samples.

This study investigates the fluorescence quenching mechanism of formaldehyde detection probe Naph1 and its contrast probe Naph3 in water samples and discussed the effect of the electron-donating group and electron-withdrawing group on fluorescence characteristics based on density functional theory (DFT) and time-dependent density functional theory (TD-DFT). We optimized the structures of the four probes Naph1, Naph1-S, Naph3, and Naph3-S (Scheme 1) and calculated the absorption and emission spectra, which were in good agreement with the experiment. Frontier molecular orbitals (FMOs) were used to analyze the charge arrangement in the excited state. To investigate the intramolecular proton transfer (ESIPT) phenomenon, a potential energy curve was constructed. The amount of fragment charge transfer was analyzed by the IFCT method, and then it was determined whether there was an intramolecular charge transfer (ICT) process. It was found that there was an ICT process in Naph3. The electronic effect of the functional groups did not determine the ICT characteristics and the fluorescence characteristics of the substance. Furthermore, the spin-orbit coupling  (SOC) constant based on the intersystem crossing (ISC) was supplemented, which showed that the fluorescence quenching of Naph1 and Naph3 was caused by the ISC and the corresponding quenching of Naph3-S was caused by charge transfer (CT) in the excited state.

The oxidation of cyclo-olefin by the S = 2 ground-state complex [FeIV(O)(TQA)(NCMe)]2.

Density functional theory calculation is used to investigate the oxidation of cyclo-olefin (cyclobutene, cyclopentene, cyclohexene, cycloheptene, and cyclo-octene) by the complex [FeIV(O)(TQA)(NCMe)]2+, which has S = 2 ground state, and the effect of electronic factors and steric hindrance on reaction barriers. Our results suggest that the oxo-iron(IV) complex can oxidise C-H and C = C bonds via a single-state mechanism, and two different ways of electron transport exist. The energy barriers initially decrease with increasing substrate size, and the trend then reverses. Comparison of the energy barrier in different systems reveals that except for the reaction between [FeIV(O)(TQA)(NCMe)]2+ and cycloheptene, oxo-iron(IV) complexes prefer epoxidation to hydroxylation. However, the hydroxylated product is more stable than the corresponding epoxidated product. This result indicates that the products of epoxidation tend to decompose first. The energy barrier of hydroxylation and epoxidation originates from the balance of orbital interaction and Pauli repulsion from the equatorial ligand and protons on the approaching substrate. In this regard, we calculate the weak interaction between two fragments (oxo-iron complex and substrates) using the independent gradient model and drawn the corresponding 3D isosurface representations of reactants.

Transapical Transcatheter Aortic Valve Implantation Using a New TAVI System for High-Risk Patients With Severe Aortic Stenosis.

BACKGROUND: To evaluate the safety and efficacy of transcatheter aortic valve implantation (TAVI) for high-risk patients with aortic stenosis using the J-Valve system. METHODS: 30 high-risk patients with severe AS underwent TAVI procedure were enrolled with mean age 74.5±4.5 years and mean logistic Euro-SCORE-I of 28.4±9.6%. All patients were followed up for 6 months. Outcomes were analysed in accordance with the updated standardised endpoints defined by the Valve Academic Research Consortium -2 (VRAC-2) criteria. RESULTS: VARC-2 defined device success was obtained in 93% (28 of 30 patients). No operative mortality was noted. No major complications such as third-degree AV-block, myocardium infraction or cerebrovascular events were noted during procedure and follow-up. Transvalvular PG was decreased at 6 months compared with preoperative state (PG mean: 55.4±14.9 vs 14.6±6.9mmHg p<0.01). No moderate or above degree paravalvular leakage (PVL) was noted. All patients with successful valve implantation were alive with improved exercise tolerance. CONCLUSIONS: Our initial result has demonstrated that the J-Valve system has the potential to become a feasible treatment option for high-risk patients with severe AS.

Concomitant CABG, Left Ventricular Restoration and Mitral Valve Repair for Ischemic Heart Disease.

AIM: To evaluate the effects of combined coronary artery bypass grafting (CABG), surgical left ventricular restoration (LVR), and mitral valve repair (MVP) in treating ischemic heart disease combined with mitral regurgitation; and to evaluate the different strategies of LVR and MVP. METHODS: From January 2001 to December 2015, 61 consecutive patients with left ventricular aneurysm and ischemic mitral regurgitation underwent concomitant CABG, LVR and MVP. We evaluated the clinical and echocardiographic outcomes of the patients. The mean follow-up was 5.8 ± 3.3 years. RESULTS: The operative mortality was 4.9%. One-, five-, and ten-year survival rates were 95.1%, 86.9%, and 80.3%, respectively. Mitral regurgitation, left ventricular ejection fraction (LVEF), and left ventricular end diastolic diameter (LVEDD) improved significantly after surgery (P < .001). During follow-up, 3 patients (5.2%) had moderate mitral regurgitation and 1 patient (1.9%) had severe mitral regurgitation. The clinical outcomes were not influenced by the LVR technique and MVP approach. CONCLUSION: Combined CABG, LVR, and MVP was effective for ischemic left ventricular aneurysm with mitral regurgitation. The procedure was associated with acceptable operative risk and clinical outcomes.

Determination of zeranol and its metabolites in bovine muscle and liver by a chemiluminescence enzyme immunoassay: compared to an ultraperformance liquid chromatography tandem mass spectroscopy method.

A chemiluminescent enzyme immunoassay (CLEIA) was compared to an ultraperformance liquid chromatography tandem mass spectroscopy (UPLC-MS/MS) procedure for the analysis of zeranol and its metabolites in bovine tissue samples. Apparent recoveries from fortified samples by both methods were comparable at 0.5-4.0 µg/kg and a significant correlation was obtained. For CLEIA analysis, hapten mimicking the analyte was first synthesized and conjugated with the carrier protein bovine serum albumin as the immunogen to produce monoclonal antibody. The obtained antibody showed extensive cross-reactivity toward zeranol metabolites (zearalanone). The limit of detection of CLEIA and UPLC-MS/MS was 0.05 µg/kg and 0.5 µg/kg, respectively. Recoveries of both methods for fortified samples were higher than 75.0% with the coefficient of variation less than 15%. These results indicated that the combination of screening with CLEIA and confirmation with UPLC-MS/MS for zeranol and its metabolites would be a reliable method for a large number of bovine samples.

Identification of hub genes significantly linked to tuberous sclerosis related-epilepsy and lipid metabolism via bioinformatics analysis.

Background: Tuberous sclerosis complex (TSC) is one of the most common genetic causes of epilepsy. Identifying differentially expressed lipid metabolism related genes (DELMRGs) is crucial for guiding treatment decisions. Methods: We acquired tuberous sclerosis related epilepsy (TSE) datasets, GSE16969 and GSE62019. Differential expression analysis identified 1,421 differentially expressed genes (DEGs). Intersecting these with lipid metabolism related genes (LMRGs) yielded 103 DELMRGs. DELMRGs underwent enrichment analyses, biomarker selection, disease classification modeling, immune infiltration analysis, weighted gene co-expression network analysis (WGCNA) and AUCell analysis. Results: In TSE datasets, 103 DELMRGs were identified. Four diagnostic biomarkers (ALOX12B, CBS, CPT1C, and DAGLB) showed high accuracy for epilepsy diagnosis, with an AUC value of 0.9592. Significant differences (p < 0.05) in Plasma cells, T cells regulatory (Tregs), and Macrophages M2 were observed between diagnostic groups. Microglia cells were highly correlated with lipid metabolism functions. Conclusions: Our research unveiled potential DELMRGs (ALOX12B, CBS, CPT1C and DAGLB) in TSE, which may provide new ideas for studying the psathogenesis of epilepsy.

A Janus supramolecular hydrogel prepared by one-pot method for wound dressing.

Despite the adhesive hydrogels have gained progress and popularity, it is still an enormous challenge to develop a smart adhesion hydrogel for clinical medicine, which is an asymmetric adhesion hydrogel with on-demand detachment. Motivated by the thermal phase transition mechanism of gelatin, we have synthesized a Janus supramolecular hydrogel dressing with skin temperature-triggered adhesion by a simple one-pot process. This hydrogel has asymmetric and controllable adhesion, which not only can become the external objects barrier but also can achieve repeated adhesion and on-demand detachment triggered by temperature in tens of seconds. This hydrogel presents great mechanical performance (compressive strain of 65 %, 1.38 MPa) owing to the presence of supramolecular interactions in the hydrogel. Additionally, this hydrogel exhibits excellent antibacterial activity and biocompatibility. The synergistic effect of modified gelatin and ionic liquid greatly facilitates wound healing of full-thickness skin with high wound healing efficiency (98.45 %). Therefore, thanks to all these advantages, the Janus supramolecular hydrogel can be applied for wound management and treatment, which has huge potential in healing skin wounds.

A novel multi-scale pressure sensing hydrogel for monitoring the physiological signals of long-term bedridden patients.

For long-term bedridden patients who need to wear diapers, the timely replacement of diapers is very important to ensure their quality of life. Therefore, it is urgent to develop a pressure sensor that can monitor the physiological conditions of patients in real time. Inspired by the multi-scale network structure of the multi-fiber protein in the muscle, a multi-scale hydrogel as a pressure sensor was prepared by introducing micron-scale hydrogel microspheres as physical crosslinking agents. Compared with the traditional polyacrylamide hydrogel (0.17 MPa of compressive strength), the multi-scale hydrogel showed a higher compressive strength of up to 1.37 MPa. Meanwhile, the hydrogel exhibited better pressure sensitivity (0.59 kPa-1) than the existing hydrogels (0.27-0.40 kPa-1). The sensor prepared by this hydrogel could monitor the patient's physiological condition (urine outflow and urinary filling) in real time through the conductivity response to ion concentration and pressure, and then transmit the signal to the caregivers in time to avoid skin damage. This multi-scale hydrogel provided a great convenience for the physiological monitoring of long-term bedridden patients by acting as a pressure sensor.

Modulating the performance of lipase-hydrogel microspheres in a "micro water environment".

In our previous work, we successfully stimulated lipase activity in an anhydrous reaction system using porous polyacrylamide hydrogel microsphere (PPAHM) as a carrier of lipase and free water. However, the effect of the existence state and content of water in lipase-porous polyacrylamide hydrogel microsphere (L-PPAHM) on the interfacial activation remained unclear. In this work, L-PPAHM with different water contents were obtained by water mist rehydration and were used to catalyze the synthesis of conjugated linoleic acid ethyl ester (CLA-EE). The results revealed that there were three existence states of water in L-PPAHM: bound water, semi-bound water and free water, and free water provided the "micro water environment" for the interfacial activation of lipase. The reusability of L-PPAHM with different water contents showed that the activity and stability of L-PPAHM could be achieved by varying the water content of L-PPAHM. The proportion of free water in L-PPAHM increased, and the activity of L-PPAHM increased, but the strength of hydrogen bond interaction between PPAHM and lipase weakened, resulting in the decrease of stability. L-PPAHM with 2/3 of water absorption could ensure sufficient immobilized lipase activity and stability, and its water absorption property could reduce the free water generated during esterification, thus increasing the yield of CLA-EE.

Investigation on non-radioactive behavior of an acylhydrazone-based fluorescent probe: Coexistence of PET and TICT mechanisms.

A fluorescent probe (E)-((2,4-dihydroxybenzyl)diazenyl)(pyridin-2-yl)methanone (HL) to effectively and selectively detect Al3+ was designed and synthesized in the experiment. Herein, we explained the excited state dynamics mechanism of HL by using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The potential energy surfaces (PESs) proved that the excited-state intramolecular proton transfer (ESIPT) process hardly occurs due to the high reaction barriers, so the fluorescence quenching behavior of HL was not based on ESIPT. The frontier molecular orbitals (FMOs) and spectral properties were analyzed to better understand the origination of fluorescence quenching. It was found that an electron on C = N in HL could be transferred to the fluorophore during excitation in the absence of Al3+, accompanied by the PET process. The excited state could undergo a twisted intramolecular charge transfer (TICT) process, releasing non-radiative decay. After binding to Al3+, the photo-induced electron transfer (PET) process has no longer occurred, and the TICT process is eliminated, resulting in a significant fluorescence enhancement. Therefore, the calculation results well explain the quenching and enhancement behaviors of fluorescence before and after the reaction with Al3+.

Exploring the influence of intermolecular hydrogen bonding on the fluorescence properties of HQCT and HQPH fluorescent chemosensors.

Recently, two trace water detection probes, 8-hydroxyquinoline-2-carboxaldehyde thiosemicarbazone(HQCT) and 8-hydroxyquinoline-2-carboxaldehyde (pyridine-2-carbonyl)-hydrazine(HQPH) have been successfully designed in the experiment. The original intramolecular proton transfer can be prevented by the water molecules, leading to fluorescence quenching. In order to investigate the fluorescence quenching mechanism, the effect of water molecules on the excited state proton transfer process will be studied in detail. In this contribution, the six models have been optimized and the related analysis have been carried out. When water molecules are involved in the proton transfer process, the energy barrier decreases significantly and the conversion of the enol structure to the keto structure is accelerated. Moreover, the intermolecular hydrogen bonding, not participating in the proton transfer process, can facilitate the proton transfer process by affecting the distribution of the electrostatic potential within the molecule, which in turn lowers the energy barrier for proton transfer.

Biomass-based hydrogels with high ductility, self-adhesion and conductivity inspired by starch paste for strain sensing.

Currently, hydrogel sensors for health monitoring require external tapes, bandages or adhesives to immobilize them on the surface of human skin. However, these external fixation methods easily lead to skin allergic reactions and the decline of monitoring accuracy. A simple strategy to solve this problem is to endow hydrogel sensors with good adhesion. Inspired by the starch paste adhesion mechanism, a biomass-based hydrogel with good conductivity and high repetitive adhesion strength was prepared by introducing modified starch into polyacrylic acid hydrogel system. The properties of biomass-based hydrogels could be controlled by changing the proportion of amylose and amylopectin. The biomass-based hydrogel exhibited a variety of excellent properties, including good stretchability (1290 %), high adhesion strength (pig skin: 46.51 kPa) and conductivity (2.3 S/m). Noticeably, the repeated adhesive strength of biomass-based hydrogel did not decrease with the increase of adhesion times. The strain sensor based on the biomass-based hydrogel could accurately monitor the large-scale and small movements of the human body, and had broad application prospects in the field of flexible wearable devices.

A ionic liquid enhanced conductive hydrogel for strain sensing applications.

Strain-sensitive and conductive hydrogels have attracted extensive research interest due to their potential applications in various fields, such as healthcare monitoring, human-machine interfaces and soft robots. However, low electrical signal transmission and poor tensile properties still limit the application of flexible sensing hydrogels in large amplitude and high frequency motion. In this study, a novel ionic liquid segmental polyelectrolyte hydrogel consisting of acrylic acid (AAc), 1-vinyl-3-butylimidazolium bromide (VBIMBr) and aluminum ion (Al3+) was prepared by molecular design and polymer synthesis. The cationic groups and amphiphilicity of ionic liquid chain segments effectively improve the tensile behavior of the polyelectrolyte hydrogel, with a maximum tensile strength of 0.16 MPa and a maximum breaking strain of 604%. The introduction of ionic liquid segments increased the current carrying concentration of polyelectrolyte hydrogel, and the conductivity reached the initial 4.8 times (12.5 S/m), which is a necessary condition for detecting various amplitude and high frequency limb movements. The flexible electronic sensor prepared by this polyelectrolyte hydrogel efficiently detects the movement of different parts of the human body stably and sensitively, even in extreme environment (-20 °C). These outstanding advantages demonstrate the great potential of this hydrogel in healthcare monitoring and wearable flexible strain sensors.

Exploring the relationship between the "ON-OFF" mechanism of fluorescent probes and intramolecular charge transfer properties.

In this study, the excited state charge distribution characteristics and fluorescence mechanism of HClO detection probes HN-ClO (weak fluorescence) and HN-ClO-F (strong fluorescence) probes were investigated based on density functional theory (DFT) and time-dependent density functional theory (TDDFT). The results of electrostatic potential (ESP) map and hole-electron analysis show that the HN-ClO and HN-ClO-F probes have obvious charge separation characteristics in the excited state. The excited state energy decomposition and Merz-Kollman charge analysis demonstrate the existence of distinct planar intramolecular charge transfer (PICT) features in HN-ClO and HN-ClO-F. Due to the strong charge coupling caused by the planar structure, the fluorescence of HN-ClO-F could occur. Furthermore, the weak fluorescence of HN-ClO is caused by inter-system crossing (ISC) between S1 and T1 state. Our result proves that the ICT process could exist in HN-ClO-F, but the PICT process does not cause fluorescence quenching, which have provided an excellent supplement to the mechanism of fluorescent probes. The conclusion is consistent with the fluorescence phenomenon observed in the experiment.

Hydrogen-bonded lipase-hydrogel microspheres for esterification application.

Lipase is the most widely used enzyme in industry. Due to its unique "lid" structure, lipase can only show high activity at the oil-water interface, which means that water is needed in the catalytic esterification process. However, the traditional lipase catalytic system cannot effectively control "micro-water" in the esterification environment, resulting in the high content of free water, which hinders the esterification reaction and reduces the yield. In this paper, a promising strategy of esterification catalyzed by polyacrylamide hydrogel immobilized lipase is reported. The porous polyacrylamide hydrogel microspheres (PHM) prepared by inverse emulsion polymerization are used as carrier to adsorb lipase by hydrogen bonding interaction. These hydrogel microspheres provide a "micro-water environment" for lipase in the anhydrous reaction system, and further provide an oil-water interface for "interface activation" of lipase. The obtained lipase-porous polyacrylamide hydrogel microspheres (L-PHMs) exhibit higher temperature and pH stability compared with free lipase, and the optimum enzymatic activity reach 1350 U/g (pH 6, 40 °C). L-PHMs can still remain about 49% of their original activity after 20 reuses. Furthermore, L-PHMs have been successfully applied to catalyze the synthesis of conjugated linoleic acid ethyl ester. The results suggest that this immobilization method opens up a new way for the application of lipase in ester synthesis.

Polyionic liquids supramolecular hydrogel with anti-swelling properties for underwater sensing.

The preparation of hydrogel-based wearable sensors for underwater application with high mechanical properties and electrical conductivity is an urgent challenge. Here, a supramolecular hydrogel based on polyionic liquids was designed and prepared for underwater sensing. The introduction of functional ionic liquid structures effectively increased the supramolecular interaction in the hydrogel network, which made the hydrogel successfully resist the interference of external water molecules. Depending on the effect of charge and hydrophobic interactions, this supramolecular hydrogel sensor exhibited high tensile (759 %), high tensile strength (0.23 MPa), high sensitivity (GF = 10.76) and extensive antibacterial properties, even in seawater environment. The obtained hydrogel sensor successfully monitored the swimming posture, which was helpful to digitally reflect the limb movement of athletes during underwater sports. This work made progress in the field of underwater wearable sensors based on hydrogels, and this design of multifunctional hydrogel provided a new idea for the development of functional sensors.

Lipase-polydopamine magnetic hydrogel microspheres for the synthesis of octenyl succinic anhydride starch.

Octenyl succinic anhydride (OSA) starch is an important edible additive in the food field, and its synthesis method has attracted much attention. Lipase as a biocatalyst can improve the synthesis efficiency of OSA starch, and significantly inhibit the occurrence of side reactions. However, free lipase has not been widely applied in the synthesis of OSA starch due to the difficulty of separation from starch and poor reusability. In this work, a promising strategy for the synthesis of OSA starch catalyzed by lipase immobilized on polydopamine magnetic hydrogel microspheres (PMHM) is reported. The prepared lipase-polydopamine magnetic hydrogel microspheres (L-PMHM) can be uniformly dispersed in starch slurry, which is conducive to the full contact between lipase and starch. L-PMHM (Km =2.6276 µmol/mL) exhibits better affinity to the substrate than free lipase (Km = 3.4301 µmol/mL). Compared with the OSA starch catalyzed by free lipase (DS = 0.0176), the degree of substitution of OSA starch catalyzed by L-PMHM is up to 0.0277 in a short reaction time. In cyclic catalysis, L-PHMM can remain about 48 % of their original activity after 20 reuses and can be quickly separated from the product. These results suggest that L-PMHM has great potential as a biocatalyst for the efficient synthesis of OSA starch.