Accurate Molecular Weight Research Articles

Urinary Fatty Acid Composition and Biomarkers Discovery for Type 2 Diabetic Patients Based on Ultra-Performance Liquid Chromatography-Quadrupole/Time of Flight Mass Spectrometry and Multivariate Statistical Analysis

A strategy of high sensitive assay method of urine fatty acid profiles was established based on ultra-performance liquid chromatography-quadrupole time of flight-mass spectrometry (UPLC/Q-TOF) and applied in metabolomics research of diabetes mellitus. In this way, 19 fatty acids including two pair of hard-resolved isomers were separated well in only 13 minutes, and Q-TOF mass spectrometry reduced the matrix interference of urine samples by high resolution and accurate molecular weights. Under the optimal conditions, fatty acid profiles of 93 cases of urine samples were analyzed. Fatty acid profiles of type 2 diabetes mellitus showed large differences from health controls based on multivariate data analysis; C16:0, C18:0, C18:2, C20:5, and C22:6 were screened as potential clinical biomarkers. This work is complementary to the clinical diagnosis of diabetes mellitus; additionally, noninvasive testing of urine samples made it more convenient for examination while reducing the patient's pain and improving their living conditions.

Extraction of natural rubber and resin from guayule using an accelerated solvent extractor

Accelerated solvent extraction is a relatively rapid automated method for extracting compounds of interest from plant materials. We have developed a sequential solvent extraction method that can be used to accurately quantify the rubber and resin in samples of guayule (Parthenium argentatum Gray), a new industrial crop now in commercial production in Arizona, USA. The method assumes that the sample has been dried under suitable drying conditions. The ASE method requires the resin extraction protocol (three 20-min cycles) to be performed first, in gaseous N2 and at 40°C. Higher temperatures degrade the thermolabile rubber made by guayule to acetone soluble fragments. Thus, acetone temperatures above 40°C overestimate the resin fraction and underestimate the rubber fraction in the samples being analyzed. Following removal of the resin fraction, samples are then extracted with either cyclohexane or hexane at 140°C. Cooler temperatures do not fully solubilize the high molecular weight guayule rubber in the three 20-min cycles. Quantification of the two extracted analytes can be performed gravimetrically, as we did in this paper, or using spectrophotometric methods. Although this high rubber extraction temperature results in good rubber quantification, the partial degradation that occurs prevents accurate molecular weight determination.

Screening out Potential Cardio-Toxic Components of Chinese Herb Radix Aconiti Lateralis in Rat Dosed Plasma by High Performance Liquid Chromatography/Electrospray Ionization Quadrupole Time-Of-Flight Mass Spectrometry

This study established a new, rapid, and accurate method for bioactive compound screening by the combination of serum pharmacochemistry and serum pharmacology based on a spectrum-effect relationship model. HPLC/ESI-Q-TOF-MS was used for the chemical profiling of samples of dosed plasma, control plasma, and Radix Aconiti Lateralis decoction. A comparison was made of the resulting chemical profiles, which totaled 20 compounds including 16 prototype compounds and 4 metabolites derived from SF decoction that were detected as potential bioactive components. Using MS/MS analysis and accurate molecular weight assessments of TOF, 17 components in 20 potential bioactive compounds were structurally identified. Moreover, the pretreated plasma samples were injected into venous sinus of isolated toad hearts to investigate the cardio-toxicity according to heart ratio (HR) situation and electrocardiograph (ECG) parameters, including PR interval, QRS interval, and QT interval. Finally, 4 compounds in these 20 potential bioactive components that had closest correlation with 4 cardio-toxic experimental indexes respectively were investigated by spectrum-effect relationship model for the first time. The 4 compounds were considered as the real cardio-toxic components. This study proposed a series of potential bioactive components in Radix Aconiti Lateralis and provided a general research pattern to identify the potential bioactivity compounds in Chinese herbs or natural pharmacy.

Comprehensive characterization of Stevia Rebaudiana using two‐dimensional reversed‐phase liquid chromatography/hydrophilic interaction liquid chromatography

Two-dimensional reversed-phase liquid chromatography/hydrophilic interaction liquid chromatography (2D-RPLC/HILIC) system was successfully applied for comprehensive characterization of steviol glycosides from Stevia rebaudiana. The experiments were performed in offline mode using an XCharge C18 column in first dimension and an XAmide column in second dimension. In first dimension, preliminary separation of Stevia aqueous extract was accomplished and 30 fractions were collected. Then fractions 1-20 were selected for further purification and 13 compounds with high purity were obtained in second dimension. Comprehensive characterization of these compounds was completed by determination of their retention time, accurate molecular weight, diagnostic fragmentation ions, and nuclear magnetic resonance spectroscopy. As a result, all nine known steviol glycosides, as well as other four steviol glycosides were fully purified. The result demonstrated that this procedure is an effective approach for the preparative separation and comprehensive characterization of steviol glycosides in Stevia. This 2D-RPLC/HILIC method will be a promising tool for the purification of low-abundance compounds from natural products.

Molecular Weight Distributions of Polymer Solutions: Combination of Field Flow Fractionation (FFF) and Analytical Ultracentrifugation (AUC)

Molecular weight, distribution, as well as other molecular characteristics are important drivers in determining the potential behaviors and hence applications of polymeric materials. Out of different methods available for the determination of molecular weight and its distribution, field flow fractionation (FFF) provides absolute molecular weight values and accurate molecular weight distributions. Analytical ultracentrifugation (AUC), on the other hand, relies on the exact density of the polymer materials in solution to determine the accurate molecular weight and its distribution and in the absence of knowledge of exact density, AUC is less accurate than the FFF method. However, combination of the two methods can be achieved to gain insights into the other molecular characteristics of swollen polymer chains. One such example is the determination of the exact density of the swollen polymer chains by the incorporation of the molecular weight information from FFF into AUC analysis. Based on the comparison of the optimized polymer chain density with the bulk density, it was observed that the polyacrylic acid and polyacrylamide chains were swollen in the range of 27 to 29%. Moreover, the FFF and AUC can also complement each other in enhancing the range of characterization possible with the two methods when used separately.

Identification of A-series oligomeric procyanidins from pericarp of Litchi chinensis by FT-ICR-MS and LC-MS

Procyanidin oligomers from litchi pericarp (Litchi chinensis) were isolated and identified by online analysis. Accurate molecular weight (MW) distribution and composition of the procyanidin extracts were recorded on an Apex-Qe–FT–ICR mass spectrometer. The MW range of litchi procyanidins was from 289.07151 to 1439.30529 m/z and composed of A- and B-series oligomeric procyanidins. The variety of the main procyanidins (DP < 5) was identified by HPLC and LC–ESI-MS analysis. There are more than 41.7% of A-series procyanidins in the oligomeric procyanidins, however, B-series procyanidins takes only 24.1% of the litchi pericarp extracts. In this study, we determined the effects of (−)-epicatechin, A-type procyanidin dimer (A2) and trimer, epicatechin-(4β→8, 2β→O→7)-epicatechin-(4β→8)-epicatechin from litchi pericarp on free radical scavenging. The results showed that A-type procyanidin dimer and trimer both had a strong scavenging ability on DPPH and OH, indicating that litchi is a new plant source of A-type procyanidins and natural antioxidant.

Analysis of gingerol-related compounds in fresh ginger by HPLC-ESI-Q-TOF-MS/MS

To establish a rapid method for analysis of gingerol-related compounds in fresh ginger by using high performance liquid chromatography coupled with electron spray ionization-quadrupole-time of flight mass/mass spectrometry (HPLC-ESI-Q-TOF-MS/ MS). The gingerol-related compounds in fresh ginger was separated by an Inertsil ODS-SP column (4.6 mm x 250 mm, 5 microm) using a binary eluent under gradient conditions. The analytes were detected by ESI-Q-TOF-MS/MS in positive ion mode to obtain MS and MS/MS spectra and to extract molecular weights. From the MS data, the accurate molecular weights of gingerol-related compounds were obtained, and from the MS/MS data, the (+) ESI-Q-TOF-MS/MS fragments were obtained. 25 gingerol-related compounds were identified from fresh ginger by attentive studying on the mass spectra of compounds and comparing with reference data reported in the literature, respectively. This method was certified to be accurate and reliable and can be used for the rapid analysis of gingerol-related compounds in fresh ginger.

Separation and identification of flavonoids from complex samples using off-line two-dimensional liquid chromatography tandem mass spectrometry

In this study, a LC-based identification strategy was proposed and off-line two-dimensional liquid chromatography was developed for the separation and identification of flavonoids from complex samples. The highly orthogonal separation system was composed of a CD column, an OEG column and an XTerra C(18) column. The CD column was employed for the first dimensional separation and the OEG column and XTerra C(18) column were used for the second dimensional separation in parallel. A mixture of six traditional Chinese medicines was used as a complex sample in testing this method. Unknown peaks were identified by matching their retention times and accurate mass molecular weights with those of references. The identification efficacy of parallel unidimensional liquid chromatography and off-line two-dimensional liquid chromatography was compared, and the latter was demonstrated to be more efficient for the identification of target compounds-especially co-eluted compounds or minor compounds from complex samples.

Highly Efficient Extraction of Serum Peptides by Ordered Mesoporous Carbon

Human serum is of great importance for organ function and the potential diagnosis of diseases. Serum biomarkers have been widely applied in clinical diagnosis and disease therapies. Endogenous serum peptides are an important class of potential biomarkers for the elucidation of biological and pathological variations in the serum. However, owing to the complexity and the highly dynamic range of protein concentrations in serum, the discovery of serum peptides, especially those at low abundance levels from minuscule blood samples, is still a challenge. With regard to obtaining serum peptides, organic solvent precipitation is a simple method for the removal of highly abundant proteins. However, the difficulty in discriminating between peptides and proteins together with the inevitable loss of peptides during the removal of proteins by solvent precipitation makes this method inefficient for the extraction of peptides. Centrifugal ultrafiltration (UF) with an accurate molecular weight cutoff is considered to be a very useful technology for the separation of proteins with low and high masses. By using UF coupled with a nanospray ionization hybrid ion trap/Fourier transform mass spectrometer, 300 unique peptides were identified from a 60 mL of serum sample. However, the coconcentration of small molecules and salts result in inefficient peptide extraction and severe interference to the MS detection. Therefore, additional peptide enrichment as well as salt removal by solid phase extraction (SPE), particularly using hydrophobic C18 adsorbents, has to be adopted before MS analysis. To simplify the extraction of peptides from serum, ordered mesoporous silica materials have been applied to enable the selective extraction of serum peptides rather than large proteins by the size-exclusion effect of the mesopores. Unfortunately, owing to the inherently insufficient hydrophobicity of silica some peptides are not extracted, thus resulting in a low number of unique peptides being identified. Surface modifications to mesoporous silica and titanium oxide materials have been developed for the enrichment of some specific posttranslational peptides, such as phosphopeptides and glycopeptides in serum. So far, a highly efficient general method for the extraction of a broad spectrum of serum peptides rather than for specific peptides is still absent; such a method would be a crucial technology for the discovery of serum biomarkers from very small blood samples. Herein, we describe the synthesis of an ordered mesoporous carbon material (OMC) and its use for the enrichment of a broad spectrum of endogenous peptides from serum. The expected high efficiency of this method for peptide enrichment is due to the distinct hydrophobicity of carbon as well as the size exclusion of the mesopores against serum proteins. The procedure for the extraction of a broad spectrum of endogenous serum peptides using OMC is illustrated in Scheme 1.

Structural determination by atmospheric pressure photoionization tandem mass spectrometry of some compounds isolated from the SARA fractions obtained from bitumen

We have identified compounds obtained from the SARA fractions of bitumen by using atmospheric pressure photoionization mass spectrometry and low-energy collision tandem mass spectrometric analyses with a QqToF-MS/MS hybrid instrument. The identified compounds were isolated from the maltene saturated oil and the aromatic fractions of the SARA components of a bitumen. The QqToF instrument had sufficient mass resolution to provide accurate molecular weight information and to enhance the tandem mass spectrometry results. The APPI-QqToF-MS analysis of the separated compounds showed a series of protonated molecules [M + H](+) and molecular ions [M](+▪) of the same mass but having different chemical structures, in the maltene saturated oil and the aromatic SARA fractions. These isobaric ions were a molecular ion [M2 ](+▪) at m/z 418.2787 and a protonated molecule [M5 + H](+) at m/z 287.1625 in the saturated oil fraction, and molecular ions [M6 ](+▪) at m/z 418.1584 and [M7 ](+▪) at m/z 287.1285 in the aromatic fraction. The identification of this series of chemical compounds was achieved by performing CID-MS/MS analyses of the molecular ions [M](+▪) ([M1 ](+▪) at m/z 446. 2980, [M2 ](+▪) at m/z 418.2787, [M3 ](+▪) at m/z 360.3350 and [M4 ](+▪) at m/z 346.2095) in the saturated oil fraction and of the [M5 + H](+) ion at m/z 287.1625 also in the saturated oil fraction. The observed CID-MS/MS fragmentation differences were explained by proposed different breakdown processes of the precursor ions. The presented tandem mass spectrometric study shows the capability of MS/MS experiments to differentiate between different classes of chemical compounds of the SARA components of bitumen and to explain the reasons for the observed mass spectrometric differences. However, greater mass resolution than that provided by the QqToF-MS/MS instrument would be required for the analysis of the asphaltene fraction of bitumen.

A novel PAGE buffer for faster runs and sharper protein bands

Since the mid‐70s Laemmli's protocol based on a Tris‐glycine‐SDS buffer system has been widely used for analyzing protein mixtures by PAGE. Laemmli's buffer system allows clear and accurate molecular weight estimation of proteins in complex samples from a wide variety of sources, but at the cost of long electrophoresis time. Modifications and improvements of this method reducing total run‐time are limited to mainly high priced precast gels.In this work, we demonstrate an improved Laemmli method offering significant cut in run‐time and improved sharpening of protein bands. The patent pending modifications apply to the running buffer system which can be run at higher voltages without generating high heat and impacting gel performance. We show that typical mini‐gels (10 x 10 cm gel) cast with the Laemmli recipe can be run 50 to 60% faster and still maintain a wide separation range similar to porosity gradient gels. In fact, a 10% Laemmli discontinuous mini‐gel will provide ultra‐fine band resolution over a wide molecular weight range (10 to 240 kDa) in less than 30 minutes using this unique running buffer. The need for gradient gels may be over since a uniform concentration gel can now fractionate proteins covering a wide range of molecular masses in half the time.

A new method for chemical identification based on orthogonal parallel liquid chromatography separation and accurate molecular weight confirmation

Recent advances in the theory and application of orthogonal LC separation have allowed for the establishment of a more effective method for the chemical identification of target compounds in complex samples, especially structurally similar compounds. In this study, a new chemical identification method based on orthogonal parallel separation and accurate molecular weight confirmation was developed. An orthogonal separation system consisting of an XTerra MS C 18 column, a home-made Click OEG column, and a Click CD column was established for separation and identification. In addition, 82 flavonoids were selected as references, to be used for the construction of a library. Retention times of each reference flavonoid on each column and accurate molecular weights were recorded and imported into a searchable library as “tags” for the unknown screening. For the method validation, two complex mixtures, fractions of Dalbergia odorifera T. Chen and Scutellaria baicalensis Georgi, specifically, were separated and identified. In total, nine compounds were unequivocally identified by retention time and confirmation of accurate molecular weight, demonstrating that this method is suitable and efficient for the chemical identification of complex samples.

Molecular weight determination of high molecular mass (glyco)proteins using CGE‐on‐a‐chip, planar SDS‐PAGE and MALDI‐TOF‐MS

The molecular weights (MW) of seven (glyco)proteins, of which five were plasma-derived, with MWs higher than 200 kDa were determined with three techniques: CGE-on-a-chip, SDS-PAGE and MALDI-TOF-MS. While the analysis of medium to high MW proteins with SDS-PAGE was an already well-established technique, the usefulness of MALDI-TOF-MS for the exact MW determination of high mass proteins was only partly described in literature so far. CGE-on-a-chip is the newest of all three applied techniques and was so far not applicable. Therefore, it was not evaluated for high MW (glyco)proteins. All proteins were analyzed under nonreducing as well as reducing conditions. In this work, it was demonstrated that all three described techniques were capable of determining the MW of all high molecular weight (glyco)proteins. The noncommercial CGE-on-a-chip assay allowed for the first time the electrophoretic separation of proteins in the MW range from 14 to 1000 kDa. MW assignment was limited to 500 kDa in the case of SDS-PAGE and 660 kDa in the case of the high MW CGE-on-a-chip assay. With the proper matrix and sample preparation, analysis with a standard MALDI-TOF-MS provided accurate MWs for all high MW proteins up to 1 MDa.

Infrared Irradiation in the Collision Cell of a Hybrid Tandem Quadrupole/Time-of-Flight Mass Spectrometer for Declustering and Cleaning of Nanoelectrosprayed Protein Complex Ions

Herein we report the performance of a hybrid quadrupole time-of-flight tandem mass spectrometer with an improved designed for coaxial infrared laser introduction for the characterization and dissociation of large protein complex ions and their aggregates formed under nanoelectrospray ionization. The major improvement from the original design (Raspopov, S. A.; El-Faramawy, A.; Thomson, B. A.; Siu, K. W. M. Anal. Chem. 2006, 78, 4572-4577) involves the use of a hollow silica waveguide and physical isolation of the infrared laser. Large model protein complex ions and their aggregates examined include alcohol dehydrogenase, avidin, GroEL, and others. Gentle heating of these complexes with the infrared laser facilitated declustering and resulted in better resolved mass spectral peaks and more accurate molecular-weight measurements.

Analysis of the bioactive constituents of ChanSu in rat plasma by high performance liquid chromatography with mass spectrometric detection

A plasma pharmacochemistry analysis of the bioactive constituents in rat plasma after oral administration of ChanSu was performed. High performance liquid chromatography coupled with the electrospray ionization mass spectrometry techniques of HPLC/ESI-IT-MS/MS and RRLC/ESI-Q-TOF-MS were used for the chemical profiling of samples of dosed plasma, control plasma and ChanSu extract. Comparative analysis of the resulting chemical profiles revealed 20 prototype compounds and 4 metabolites derived from ChanSu as potential bioactive components. By MS/MS analysis and accurate molecular weight assessments, the majority of these bioactive components (19 prototype compounds and 2 metabolites) were structurally identified. Moreover, seven were confirmed by comparing their retention behaviors using MS and MS/MS analysis. This study proposes a series of potential bioactive components of ChanSu, which we hope will lead to new drug discovery based on ChanSu and other traditional Chinese medicines.

Identification and characterization of flavonoids from semen zizyphi spinosae by high-performance liquid chromatography/linear ion trap FTICR hybrid mass spectrometry

Semen zizyphi spinosae (SZS) has been used to treat insomnia and anxiety for thousands of years. In this paper, a novel high-performance liquid chromatography coupled with the photodiode array detector/linear ion trap-MS n (HPLC-PDA/LTQ-MS n ) method was established to separate and identify flavonoids from the extract of SZS. Separation was performed on an HYPERSIL C18 column by gradient elution using CH3CN/H2O–CH3COOH as the mobile phase at a flow rate of 0.8 ml/min. UV spectral data, accurate molecular weights, and multi-stage MS/MS fragmentation information were obtained. Electrospray ionization/MS/MS fragmentation patterns were proposed. Nineteen flavonoid glycosides were identified or tentatively characterized based on their retention time, UV spectral data, accurate molecular weights, and mass fragmentation behavior. The method was useful for separation and identification of the flavonoid components from SZS and could be applied to other complex samples, especially for minor constituents.

A comparison of nano-electrospray gas-phase electrophoretic mobility macromolecular analysis and matrix-assisted laser desorption/ionization linear time-of-flight mass spectrometry for the characterization of the recombinant coagulation glycoprotein von W

Von Willebrand factor (VWF), an adhesive glycoprotein with an approximate molecular weight (MW) of the monomer of 260 kDa, circulates in human blood plasma as a series of multimers ranging in size up to 20.000 kDa; thus the determination of the accurate MW of the monomer is of great importance and due to its high MW quite challenging. In this study accurate MW determination of intact recombinant VWF monomer (rVWF) was performed with GEMMA (gas-phase electrophoretic mobility macromolecular analysis) and MALDI TOF MS (matrix-assisted laser desorption/ionization linear time-of-flight mass spectrometry). Three rVWF preparations with differing buffer systems and glycoprotein concentrations were analyzed. First investigations directed towards heterogeneity determination by means of capillary gel electrophoresis (CGE)-on-the-chip with a laser-induced fluorescence detector revealed two compounds (MW of 277 kDa (migration time 44.3 s) and 341 kDa (migration time 49.5 s)) present in each sample to varying extents, namely mature and pro-rVWF. MALDI MS analysis in the linear positive ion mode allowed the detection of mature rVWF with an exact MW of 256.1 kDa (+/-0.8%) and pro-rVWF with a MW of 349.8 kDa (+/-0.8%). Two samples containing pro-rVWF in very minor concentration resulted in GEMMA detection of the mature rVWF with a MW of 227.4 kDa (+/-2.5%), derived from the measured globular size of 10.9 nm. For one sample containing both rVWF species in almost equal concentrations no differentiation of the two species was possible with GEMMA. Due to its lower resolution only a peak representing a mixture of both species at 11.8 nm could be observed, yielding a MW of 298.8 kDa (+/-1.6%).

Development of a microfluidics‐based gel protein recovery system

A PMMA microfluidic chip, in which fluid is manipulated to transport protein from a PAGE gel piece to a collection reservoir via a microfluidic channel, has been developed. The protein sample is mobilized out of the gel (loaded in a chip access hole) into a low EOF-CE microfluidic channel under the influence of an electric field. Simultaneously, hydrostatic pressure from the filled buffer reservoirs is used to direct the protein sample to a third reservoir, through a field-free channel connected to the electrophoresis channel. Using this novel process of protein transport from a gel sample, proteins from Coomassie-stained gels have been transferred into solution in 15-30 min, with good sample recovery, using a run buffer containing an anionic acid-labile surfactant. A variety of small- and medium-sized proteins were successfully recovered and detected using both electrospray and MALDI MS over gel loads of 0.1-10 microg. This technological tool is very important for extracting quality intact protein samples from polyacrylamide gels, from which accurate protein molecular weights and protein sequences can be obtained using intact molecules.

Quality Assessment of Granule of Danshen Extract by High Performance Liquid Chromatography

Aim To evaluate the quality of the granule of Danshen extract (GDE) by simultaneously determining the phenolic and tanshinone components with high performance liquid chromatography. Methods A Waters SymmetryShield RP18 (2.1 mm × 100 mm, 3.5 μm) with a Waters symmetryShield RP18 guard column (2.1 mm × 10 mm, 5 μm) was used for the analysis. The separation was performed with a gradient mobile phase of A (0.1% formic acid in water) and B (0.1% formic acid in acetonitrile) at a flow rate of 0.2 min·mL −1. The column was thermostated at 30 °C and the detection wavelength was set at 280 nm. Peaks were identified by comparing the accurate molecular weight with Waters Q-TOF premier system. Results HPLC profiles of GDE showed different patterns. Eight major components were quantitative analysis, and contents of the major components in GDE varied between manufacturers. The total amounts of major components in the granules were less than or equivalent to the amount in the decoction of Danshen, and the daily amounts of the major components in the commercial Danshen granules were only about 1/65-1/2.8 of those in the decoction of Danshen. Conclusion The contents of major components in GDE varied between manufacturers and were lower than those in the decoction of Danshen. The actual values of concentrative factor of commercial GDE do not meet their labels. It was demonstrated that extract solvents, temperature and heating time are the factors to influence the composition of GDE. In conclusion, standardized criteria for the quality control of GDE should be established and the manufacturing process, the criteria for raw material selection should be assessed and improved.

Synthesis, characterizations and biocompatibility of novel biodegradable star block copolymers based on poly[(R)-3-hydroxybutyrate] and poly(ε-caprolactone)

Star block copolymers based on poly[(R)-3-hydroxybutyrate] (PHB) and poly(epsilon-caprolactone) (PCL), termed SPHBCL, were successfully synthesized with structural variation on arm numbers and lengths via coupling reactions and ring opening polymerizations. Arm numbers 3, 4 and 6 of SPHBCL were synthesized by using different multifunctional cores, such as trimethyol propane, pentaerythiritol and dipentaerthritol, respectively. Gel permeation chromatography (GPC) and (1)H and (13)C nuclear magnetic resonance were used to characterize the structure of SPHBCL. GPC failed to produce accurate molecular weights of the SPHBCL due to the discrepancy of star copolymer structures. The melting temperature of SPHBCL decreased with increasing degree of branching. Thermal decomposition temperature was revealed to be lower than that of linear block copolymer LPHBCL counterparts based on PHB and PCL. Films made from various SPHBCL copolymers had different porous or networking surface morphology, and all possessed improved biocompatibility in terms of less blood clotting and more osteoblast cell growth compared with their corresponding homopolymers PHB and PCL. Among them, it was found, however, that the 4-arm star block copolymer 4SPHBCL-25 showed unique surface properties, i.e. a regular nanoravine structure was observed by scanning electron microscopy and atomic force microscopy. This 4-arm star copolymer also showed the best biocompatibility.