Cuifen Lu

Evaluation of a novel tetra‐functional branched poly(ethylene glycol) crosslinker for manufacture of crosslinked, decellularized, porcine aortic valve leaflets

To address concerns over limitations in the clinical use of glutaraldehyde (GA) fixation in bioprosthetic heart valves, we manufactured novel, branched poly(ethylene glycol) tetraacrylate (PEG-TA) crosslinked valve leaflets and evaluated cytotoxic, thrombogenic, hemolytic, and anticalcification effects, thermal stability, and mechanical properties, in comparison to decellularized valves (control) and GA crosslinked valves. Thermal denaturation temperatures were higher for PEG-TA valve leaflets compared to control and GA crosslinked valves (p < 0.001). Leaflet hydrolyzation rate was lower for the PEG-TA group than for GA and control groups (p < 0.05). Superior cytocompatibility was found for PEG-TA group leaflets (MTT, p < 0.01. apoptosis assay, p > 0.05). No thrombogenesis was found in platelet activation tests (p < 0.0001). Hemolysis assays showed that PEG-TA leaflets would not cause damage to blood cells (p > 0.05). Excellent anticalcification properties were confirmed by von Kossa staining, western blot, and atomic absorption spectroscopy (p < 0.0001) in a rat subcutaneous embedding model. Finally, the novel PEG-TA crosslinked material exhibits improved mechanical properties as compared to GA crosslinked materials (tensile strength, p < 0.001, Youngs modulus, p < 0.001). On the basis of all results presented, it is clear that the performance characteristics of PEG-TA crosslinked valve leaflets make PEG-TA crosslinked leaflets a promising alternative for the next generation of bioprosthetic heart valve.

Green Synthesis of Tetrahydrobenzo[b]Pyrans by Microwave Assisted Multi-Component One-Pot Reactions in PEG-400

Polyethylene glycol is found to be a nontoxic and recyclable reaction medium for the microwave-assisted, multi-component one-pot reactions of aromatic aldehydes with ethyl-2-cyanoacetate and 1,3-cyclohexanedione or 5,5- dimethyl-1,3-cyclohexanedione in the presence of piperidine. This environmentally friendly microwave protocol offers ease of operation and enables recyclability of reaction medium and synthesis of a variety of substituted tetrahydrobenzo[b]pyran derivatives. It is an efficient, promising, and green synthetic strategy to construct tetrahydrobenzo[b]pyran skeleton.

Novel Synthesis of 3‐Substituted 2‐Thiohydantoins via Aza‐Wittig Reaction on Poly(ethylene Glycol)

Abstract A novel method for the liquid‐phase combinatorial synthesis of 3‐substituted‐2‐thiohydantoin has been developed by using poly (ethylene glycol)–supported isothiocyanate. The PEG‐supported isothiocyanate was obtained from the reaction of PEG with bromoacetyl bromide, followed by an aza‐Wittig reaction. Reaction of PEG‐supported isothiocyanate with various aliphatic amines offered 3‐substituted 2‐thiohydantoins in excellent yields with addition, cyclization, and cleavage reactions occurred in one pot.

A Ratiometric Fluorescent Probe for Monitoring Leucine Aminopeptidase in Living Cells and Zebrafish Model

Leucine aminopeptidase (LAP) is an important cancer-related biomarker, which shows significant overexpression in malignant tumor cells like liver cancer. Developing an effective method to monitor LAP in tumor cells holds great potential for cancer diagnosis, treatment, and management. In this work, we report a novel BODIPY-based fluorescent probe (BODIPY-C-Leu) capable of monitoring LAP in vitro and in vivo in both ratiometric and turn-on model. BODIPY-C-Leu contains an asymmetrical BODIPY dye for fluorescent signaling and a dipeptide (Cys-Leu) as the triggered moiety. Activation occurs by cleavage of the amide bond in dipeptides and subsequently an intramolecular S → N conversion to convert sulfur-substituted BODIPY to amino-substituted BODIPY, resulting in a dramatic fluorescence variation to realize the detection of LAP. Furthermore, we have successfully employed BODIPY-C-Leu to monitor LAP activity in different cancer cells, indicating that HeLa cells have a higher level of LAP activity than A549 cells. Importantly, we demonstrated the capability of the probe for real-time monitoring the drug-induced LAP level changes in zebrafish.

(S)-1-[(S)-4-Benzyl-2-thioxothia­zolidin-3-yl]-3-hydroxy­butan-1-one

The title compound, C14H17NO2S2, was synthesized by asymmetric aldol condensation of N-acylthiazolidinethione with acetaldehyde. In the molecule, the thiazolidine five-membered ring assumes an envelope conformation. Intermolecular C—H⋯O and intramolecular O—H⋯O and C—H⋯S hydrogen bonding helps to stabilize the structure.

Synthesis of non-cross-linked polystyrene supported (4 S )-4-substituted-4,5-dihydrooxazoline

From N-Boc L-tyrosine ethyl ester, we synthesised (4S)-4-[4-(4-vinylbenzyloxy)benzyl]-4,5- dihydrooxazoline, which was copolymerized with styrene to obtain non-cross-linked polystyrene supported 2-hydrogen oxazoline in 29.4% yield.

Synthesis of non-cross-linked polystyrene supported 5,5-dimethyl oxazolidinone chiral auxiliary

A new chiral auxiliary, non-cross-linked polystyrene supported 5,5-dimethyl oxazolidinone was synthesised in 25.1% yield using L-tyrosine as the starting material using a six-step method.

Synthesis and Applications of Tetra-functional Branched Poly（ethylene glycol） Derivative for the Decellularized Valve Leaflets Cross-linking

To investigate the effects of polyethylene glycol cross-linking on the mechanical properties, 80 porcine aortic valves were harvested, decellularized, and introduced with sulfhydryl. Then the valves were randomly assigned into 5 experimental groups and 1 control group (n=16). For the valves in those experimental groups, branched polyethylene glycol diacrylate (PEG) of 5 different molecular weights (3.4, 8, 12, 20, 40 kDa) were synthesized and cross-linked with them respectively. The efficiency of the cross-linking was determined by measuring the amount of residual thiol group and the mechanical properties of the cross-linked valve leaflets were assessed by uni-axial planar tensile testing. The efficiency of the PEG 20 kDa group was 70.72±2.33%, obviously superior to that of the other groups (p<0.05). Tensile test proved that branched PEG cross-linking can significantly enhance the mechanical behaviors of the decellularized valve leaflet and the Young’s modulus of each group was positively correlated with the molecular weight of PEG. It was concluded that branched PEG with the molecular weight of 20 kDa can effectively cross-link the decellularized porcine aortic valves and improve their mechanical properties, which makes it a promising cross-linker that can be used in the modification of decellularized tissue engineering valves.

Asymmetric synthesis of both ( R )-and ( S )-arundic acid

The asymmetric synthesis of both (R)-and (S)-arundic acid has been achieved via the key step of a stereoselective alkylation reaction using non-cross-linked polystyrene (NCPS) supported (4R)- and (4S)-2-phenylimino-2-oxazolidine as chiral auxiliaries. This method is efficient (both enantiomers were obtained in 99% ee and 60% overall yield) and the chiral auxiliaries can be recovered quantitatively by simple filtration.

A 1,2,3-triazolyl based conjugated microporous polymer for sensitive detection of p-nitroaniline and Au nanoparticle immobilization

A 1,2,3-triazolyl based fluorescent conjugated microporous polymer PTPTB was synthesized through FeCl3 promoted oxidative coupling of 1,3,5-tris(1-(3,5-di(thiophen-2-yl)phenyl)-1H-1,2,3-triazol-4-yl)benzene. The resulting product has a BET surface area of 808.6 m2 g−1 and exhibits a strong emissive peak centered at 525 nm upon excitation at 417 nm in DMF. As a chemical sensor, PTPTB showed good fluorescence sensing ability for p-nitroaniline (p-NA) with a Ksv of 7.08 × 104 M−1 and a detection limit of 4.2 × 10−6 M. The electron-rich polymer was further employed to load Au nanoparticles (NPs). The formed Au/PTPTB composite showed superior catalytic activity in the catalytic reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP) and the rate constant was obtained to be 0.812 min−1. Moreover, the catalyst can be readily recovered and reused for six runs without obvious loss of its activity.