Carboxylic Acid Side Chain Research Articles

The Molecular Design of a Macrocycle Descaling Agent Based on Azacrown and the Mechanism of Barium Sulfate Scale Removal.

The formation of barium sulfate scale is a persistent and formidable challenge across various industrial processes. In order to effectively mitigate this problem, this study proposed the development of an innovative azacrown ether-based macrocycle descaling agent. Using density functional theory, an in-depth analysis of the surface energy of different barium sulfate crystal facets was carried out, together with a detailed investigation into the adsorption properties of the functional groups on the (001) surface. A further comprehensive investigation was carried out to determine how changes in the nitrogen and oxygen atoms in the crown ether framework influence its adsorption affinity to barium ions. In addition, a detailed analysis was carried out to elucidate the molecular interactions between crown ethers with pyridine carboxylic acid side chains and barium sulfate. The newly developed decalcifying macrocycle descaling agent exhibited superior adsorption performance, achieving an adsorption energy for barium ions approximately -4.1512 ev higher than that of conventional DTPA decalcifiers. This remarkable improvement is mainly attributed to the pivotal role of electrostatic forces in the coordination process between the macrocycle descaling agent and barium ions, with an electrostatic potential value reaching -143.37 kcal/mol. This discovery not only introduces a novel approach to the removal of barium sulfate scale but also highlights the significant potential of macrocycle chemistry in industrial applications.

Enhanced Hydrogen Peroxide Decomposition in a Continuous-Flow Reactor over Immobilized Catalase with PAES-C.

Due to the specificity, high efficiency, and gentleness of enzyme catalysis, the industrial utilization of enzymes has attracted more and more attention. Immobilized enzymes can be recovered/recycled easily compared to their free forms. The primary benefit of immobilization is protection of the enzymes from harsh environmental conditions (e.g., elevated temperatures, extreme pH values, etc.). In this paper, catalase was successfully immobilized in a poly(aryl ether sulfone) carrier (PAES-C) with tunable pore structure as well as carboxylic acid side chains. Moreover, immobilization factors like temperature, time, and free-enzyme dosage were optimized to maximize the value of the carrier and enzyme. Compared with free enzyme, the immobilized-enzyme exhibited higher enzymatic activity (188.75 U g-1, at 30 °C and pH 7) and better thermal stability (at 60 °C). The adsorption capacity of enzyme protein per unit mass carrier was 4.685 mg. Hydrogen peroxide decomposition carried out in a continuous-flow reactor was selected as a model reaction to investigate the performance of immobilized catalase. Immobilized-enzymes showed a higher conversion rate (90% at 8 mL/min, 1 h and 0.2 g) compared to intermittent operation. In addition, PAES-C has been synthesized using dichlorodiphenyl sulfone and the renewable resource bisphenolic acid, which meets the requirements of green chemistry. These results suggest that PAES-C as a carrier for immobilized catalase could improve the catalytic activity and stability of catalase, simplify the separation of enzymes, and exhibit good stability and reusability.

Identification of sorbitol esterification of glutamic acid by LC-MS/MS in a monoclonal antibody stability assessment.

The stability of monoclonal antibodies (mAbs) is vital for their therapeutic success. Sorbitol, a common mAb stabilizer used to prevent aggregation, was evaluated for any potential adverse effects on the chemical stability of mAb X. An LC-MS/MS based analysis focusing on the post-translational modifications (PTMs) of mAb X was conducted on samples that had undergone accelerated aging at 40°C. Along with PTMs that are known to affect mAbs' structure function and stability (such as deamidation and oxidation), a novel mAb PTM was discovered, the esterification of glutamic acid by sorbitol. Incubation of mAb X with a 1:1 ratio of unlabeled sorbitol and isotopically labeled sorbitol (13C6) further corroborated that the modification was the consequence of the esterification of glutamic acid by sorbitol. Levels of esterification varied across glutamic acid residues and correlated with incubation time and sorbitol concentration. After 4 weeks of accelerated stability with isotopically labeled sorbitol, it was found that 16% of the total mAb possesses an esterified glutamic acid. No esterification was observed at aspartic acid sites despite the free carboxylic acid side chain. This study unveils a unique modification of mAbs, emphasizing its potential significance for formulation and drug development.

Water/Alcohol‐Processable Low‐Cost Dihydropyrazine‐Based Polymers for Highly Sensitive, Stable and Flexible Temperature Sensors

AbstractFlexible temperature sensors based on π–conjugated polymers are well‐suited for diverse applications, including food packaging and human health monitoring. Herein, novel dihydropyrazine (DHP)‐based polymers designed for the development of flexible temperature sensors are introduced. The DHP‐based polymers are synthesized via direct arylation polymerization, eliminating toxic byproducts. Polymers with carboxylate potassium salt side chains, which exhibit high solubility in green solvents like water and alcohol are obtained via post‐polymerization hydrolysis of carboxylate ester chains. Furthermore, a post‐deposition treatment converts the carboxylate potassium salt side chains into carboxylic acid side chains, resulting in highly solvent‐resistant polymers. Notably, these DHP‐based polymers exhibit moderate electrical conductivity in the range of ≈10−4 to 10−1 S cm−1 without the need for additional dopants. Resistor‐type temperature sensors based on the self‐doped DHP‐based polymers, processed with ethylene glycol (EG) on flexible polyethylene terephthalate (PET) substrates via blade coating, demonstrate an impressive temperature coefficient of resistance (TCR) of up to −1.5% °C−1 (20–60 °C) and outstanding long‐term stability under ambient conditions. This work presents a well‐founded design of π–conjugated polymers that simultaneously fulfill performance, stability, processability, and cost criteria, paving the way for practical applications of flexible and printable temperature sensors.

Hybrid insulin peptide isomers spontaneously form in pancreatic beta-cells from an aspartic anhydride intermediate

Hybrid insulin peptides (HIPs) form in beta-cells when insulin fragments link to other peptides through a peptide bond. HIPs contain nongenomic amino acid sequences and have been identified as targets for autoreactive T cells in type 1 diabetes. A subgroup of HIPs, in which N-terminal amine groups of various peptides are linked to aspartic acid residues of insulin C-peptide, was detected through mass spectrometry in pancreatic islets. Here, we investigate a novel mechanism that leads to the formation of these HIPs in human and murine islets. Our research herein shows that these HIPs form spontaneously in beta-cells through a mechanism involving an aspartic anhydride intermediate. This mechanism leads to the formation of a regular HIP containing a standard peptide bond as well as a HIP-isomer containing an isopeptide bond by linkage to the carboxylic acid side chain of the aspartic acid residue. We used mass spectrometric analyses to confirm the presence of both HIP isomers in islets, thereby validating the occurrence of this novel reaction mechanism in beta-cells. The spontaneous formation of new peptide bonds within cells may lead to the development of neoepitopes that contribute to the pathogenesis of type 1 diabetes as well as other autoimmune diseases.

Novel concrete superplasticizers with sterically hindered amines as stabilizing pendant side chains

In this work, a sterically hindered amine, 2,2,6,6-tetramethyl-4-piperidyl methacrylate (TMPMA), is introduced as a bulky pendant group to achieve steric hindrance, replacing the traditional poly(ethylene oxide) (PEO) side chains of traditional polycarboxylate ether (PCE) superplasticizers (SPs). Note that PCE is the common name for concrete superplasticizers having both carboxylic acid and PEO side-chains in which the bulky PEO pendant group exert large steric hindrance leading to good dispersion and stabilization of cement particles. In this work, the PEO side chains are replaced by a sterically hindered amine. Therefore, copolymers of methacrylic acid (MAA) and TMPMA with different molar ratios were prepared by Reversible-Addition Fragmentation Chain Transfer polymerization (RAFT). The prepared copolymers were characterized by proton nuclear magnetic resonance (1H NMR) and size exclusion chromatography (SEC) to elucidate the chemical structure and molecular weights. Rheological studies and fluidity measurements revealed that poly(MAA-co-TMPMA) SPs, which we introduce here as polycarboxylate amine (PCA) SPs, enhanced cement flowability, workability, and slump retention. Free radical polymerization (FRP) was also employed, as an industrially more relevant, more straightforward and more cost-effective synthesis technique, for the preparation of PCA SPs to reflect the possibility of scaling up these SPs via conventional polymerization methods. The resulting FRP PCA analog exhibited the same plasticizing efficacy as those prepared by RAFT polymerization, demonstrating that these polymers could have high potential in the concrete industry.

Synthesis and characterization of bioplastic curdlan esters with an introduced flexible carboxylic acid side chain

Curdlan, a linear β-1,3-glucan, was reacted with glutaric anhydride and heptanoyl chloride to afford thermoplastic curdlan esters (CrdE(HepGlu)) with a carboxylic acid side chain. CrdE(HepGlu) with a degree of substitution of the glutaric acid monoester moiety (DSGlu) in the range of 0–0.58 and that of the heptanoate moiety (DSHep = 3 − DSGlu) was prepared. The esterification of the hydroxy groups in the glucan skeleton effectively caused the cleavage of the interchain hydrogen bonds of curdlan and enhanced the formability of CrdE(HepGlu). Moreover, the flexible carboxylic acid side chain moderately affected hydrogen bonding. Thus, the glass transition temperature of CrdE(HepGlu), estimated by differential scanning calorimetry, increased with increasing DSGlu. CrdE(HepGlu) with DSGlu between 0 and 0.58 displayed high solubility in organic solvents and thermoplasticity, enabling the formation of homogeneous and free-standing films by solution casting. The mechanical properties of CrdE(HepGlu) films were evaluated by a stress−strain test, which showed that Young's modulus and the maximum stress increased with increasing DSGlu. CrdE(HepGlu) exhibited higher mechanical strength than non-hydrogen-bonded curdlan triheptanoate and hydrogen-bonded curdlan alkylcarbamates, with thermal stability comparable to that of thermally stable curdlan esters. In addition, these properties can be regulated by controlling DSGlu.

Rapid Detection of Escherichia coli: Optimized Peptide-Polythiophene Interactions Help Reduce Assay Time and Improve Naked-Eye Detection.

Recent improvements in methods for rapid detection of microbial contamination in food and water samples have aided in the development of on-site and point-of-care testing. Early detection, made possible via on-site testing, can help limit the spread of food and waterborne illnesses. Recently, we reported a novel fluorescence-based Omptin-Polythiophene assay (the assay) to detect Escherichia coli in contaminated water samples. The assay targets OmpT─an E. coli outer membrane protease─and exploits the protease's ability to cleave at dibasic sites within a peptide. By combining a peptide substrate optimized for OmpT with a conjugated polythiophene reporter molecule whose optical properties vary upon interaction with the intact or cleaved peptide, we demonstrated the detection of 1-10 CFU/mL and 105 CFU/mL E. coli in 5.5 and 1 h, respectively. In comparison, most microbial detection methods that rely on culturing and plating techniques take anywhere between 8 and 24 h to report their results. Herein we report significant improvements in the assay which include reducing the assay time from an already short 1 h to a mere 10 min for detecting E. coli in highly contaminated samples and augmenting the assay with colorimetric sensing capability for naked eye discernment under normal visible light or under UV-A light. These improvements were made possible by characterizing the optical changes resulting from the interaction of the peptide with five carboxylate-functionalized polythiophene variants carrying different 3- side chain carboxylic acids and by identifying preferential peptide substrates via the screening of ten peptide sequence variants for OmpT activity.

Chemical synthesis, NMR characterization, and anticancer activity of androstene derivatives with a C17-side chain

Cancer remains one of the leading causes of death, worldwide. In addition, the lack of efficacy and selectivity of chemotherapeutic agents for cancer cells is a challenge that needs to be addressed through the development of new drugs. Since aminosteroids are of interest in fighting cancer, our group previously reported antiproliferative activity on several cancer cell lines of two representatives, RM-133 and RM-581. To extend the structure–activity relationship study of aminosteroids, of which RM-133 (androstane) and RM-581 (estrane) are the main candidates, we performed the chemical synthesis and biological evaluation on lung (SHP-77), breast (T-47D) and prostate (DU-145, PC-3 and LAPC-4) cancer cells of four analogues of RM-581. We moved the functionalized side chain from position 2 of the androstane and estrane derivatives to incorporate it into a new chain located at position 17.Chemical synthesis took place in 2 steps from steroidal side-chain carboxylic acids, allowing to obtain 4 steroid derivatives with acceptable yields, which were fully characterized by nuclear magnetic resonance spectroscopy (1H and 13C NMR). After the evaluation of compounds 12–15, lower antiproliferative activities varying from 12 to 54%, 0–33% and 0–63% were observed for SHP-77, DU-145 and PC-3 cell lines, respectively, while higher activities varying from 33 to 62% and 45–84% were observed for T-47D and LAPC-4 cell lines, respectively, when tested at 10 µM. Overall, it was observed that these aminosteroids have a lower cytotoxic activity than that of RM-581 and, that moving the side chain from steroid position C2 to C17 is clearly detrimental for antiproliferative activity. However, this work has enabled us to expand our knowledge of the structural requirements to maintain the anticancer activity of aminosteroid derivatives.

Sensitive Detection of Sweat Cortisol Using an Organic Electrochemical Transistor Featuring Nanostructured Poly(3,4-Ethylenedioxythiophene) Derivatives in the Channel Layer.

In this study, we examined the influence of functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) nanostructures decorated on the channel layer of an organic electrochemical transistor (OECT) for the detection of sweat cortisol, an adrenocorticosteroid stress hormone. The OECT device featured a bilayer channel confined by a PEDOT:polystyrenesulfonate (PSS) underlayer and a nanostructure-decorated upper layer engineered from the monomers EDOT-COOH and EDOT-EG3 through template-free electrochemical polymerization. This molecular design allowed antibody conjugation using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysulfosuccinimide coupling through the carboxylic acid side chain, with EDOT-EG3 known to minimize nonspecific binding of biomolecules. We also engineered an OECT device having a channel area without any nanostructures to gain insight into the effect of the nanostructures on cortisol sensing. Our new nanostructure-embedded OECT device facilitated real-time detection of cortisol at concentrations ranging from 1 fg/mL to 1 μg/mL with a detection limit of 0.0088 fg/mL with good linearity (R2 = 0.9566), in addition to excellent selectivity toward cortisol among other structurally similar interfering compounds and high stability and reproducibility. With its rapid response for the detection of 100 ng/mL cortisol-spiked artificial sweat, this nanostructure-decorated OECT device has potential clinical practicality and utility in wearable sensors for future healthcare applications.

Identification of 9H-purin-6-amine derivatives as novel aldose reductase inhibitors for the treatment of diabetic complications.

A series of 9H-purin-6-amine derivatives as aldose reductase (ALR) inhibitors were designed and synthesized. Most of these derivatives, having a C6-substituted benzylamine side chain and N9 carboxylic acid on the core structure, were found to be potent and selective ALR inhibitors, with submicromolar IC50 values against ALR2. Particularly, compound 4e was the most active with an IC50 value of 0.038 μM, and it was also proved to be endowed with excellent inhibitory selectivity. The structure-activity relationship and molecular docking studies highlighted the importance of the carboxylic acid head group along with different halogen substituents on the C6 benzylamine side chain of the 9H-purin-6-amine scaffold for the construction of strong and selective ALR inhibitors.

Determining the absolute configuration of vanitaracin A, an anti-hepatitis B virus agent.

Vanitaracin A is an anti-hepatitis B virus (anti-HBV) compound isolated from the culture broth of the fungus Talaromyces sp. Vanitaracin A inhibits the entry of HBV into target cells with sub-micromolar IC50 values. While a structure-activity relationship study is highly desirable, a synthetic approach still needs to be developed, which is difficult because the absolute configurations of the six stereogenic centers in the structure of vanitaracin A have not yet been determined. In the present study, we used the crystalline sponge method to clarify the configuration of the compound after determining the absolute configuration of the secondary alcohol using a modified Mosher ester method. Combining these analyses with the NOESY spectrum of vanitaracin A and NMR analyses of the crude side-chain carboxylic acid obtained by the alkaline hydrolysis of vanitaracin A revealed the absolute configurations of all stereogenic centers in this important compound.

Characterization of Bioplastic Curdlan Esters with an Introduced Flexible Carboxylic Acid Side Chain

Characterization of Bioplastic Curdlan Esters with an Introduced Flexible Carboxylic Acid Side Chain

Studies of Surface Preparation for the Fluorosequencing of Peptides.

Silica passivating agents have shown great success in minimizing nonspecific protein binding to glass surfaces for imaging and microscopy applications. Amine-derivatized surfaces are commonly used in conjugation with amide coupling agents to immobilize peptides/proteins through C-terminal or side-chain carboxylic acids. In the case of the single-molecule fluorosequencing of peptides, attachment occurs via the C-terminus and nonspecific surface binding has previously been a source of error in peptide identification. Here, we employ fluorosequencing as a high-throughput, single-molecule sensitivity assay to identify and quantify the extent of nonspecific binding of peptides to amine-derivatized surfaces. We show that there is little improvement when using common passivating agents in combination with the surface derivatizing agent 3-aminopropyl-triethoxysilane (APTES) to couple the peptides to the modified surface. Furthermore, many xanthene fluorophores have carboxylic acids in the appended phenyl ring at positions ortho and meta or ortho and para, and the literature shows that conjugation through the ortho position is not favored. Because xanthene-derived fluorophores are commonly used for single-molecule applications, we devised a novel assay to probe the conjugation of peptides via their fluorophores relative to their C-termini on silane-derivatized surfaces. We find significant attachment to the ortho position, which is a warning to those attempting to immobilize fluorophore-labeled peptides to silica surfaces via amide coupling agents. However, eliminating all amines on the surface by switching to 3-azidopropyl-triethoxysilane (AzTES) for coupling via copper-catalyzed azide-alkyne cycloaddition (CuAAC) and omitting additional passivation agents allowed us to achieve a high level of C-terminally bound peptides relative to nonspecifically or ortho-phenyl-bound, fluorophore-labeled peptides. This strategy substantially improves the specificity of peptide immobilization for single-molecule fluorosequencing experiments.

Polyaspartic acid alleviates cadmium toxicity in rapeseed leaves by affecting cadmium translocation and cell wall fixation of cadmium

Polyaspartic acid (PASP) is a macromolecule compound with carboxylic acid side chains which is polymerized by L-aspartic acid, has been used as a biodegradable and environmentally-friendly chelating agent to enhance the phytoremediation of heavy metal-contaminated soils. Cadmium (Cd) is a toxic element for plant growth, productivity, and food security. To reveal the responses of PASP to plant physiology and morphology under Cd stress, we comprehensively analyzed soil characteristics, cell ultrastructure, reactive oxygen species (ROS), antioxidant enzymes, Cd uptake, transport, subcellular distribution, cell wall compositions, and their Cd chelating capacity in rapeseed. The results showed PASP increased the content of total N, total P, and available P in soil by 3.4%, 28.6%, and 39.8%, respectively, but did not change soil pH and available Cd. Meanwhile, PASP promoted dry mass accumulation and increased photosynthetic pigment content in rapeseed leaves by maintaining the chloroplast structure. Lower malondialdehyde (MDA) content and hydrogen peroxide (H2O2) accumulation and activated antioxidant enzymes in leaves indicate that PASP contributed to relieving Cd-induced oxidative damage to cells of rapeseed leaves. The results indicated that PASP application increased the Cd distribution ratio in root cell walls from 47.4% to 62.3% and decreased the Cd content in xylem sap by 37.8%, which ultimately reduced Cd reallocation in leaves. Additionally, higher pectin content and Cd in pectin resulted in higher Cd retention in leaf cell walls while reducing its concentration in the organelle fraction. The results indicated that 0.3% PASP effectively alleviated Cd stress in rapeseed leaves by inhibiting Cd transportation from roots, activating antioxidant enzymes to scavenge ROS, and promoting Cd chelation by cell wall pectin in leaves.

Signature of Glycylglutamic Acid Structure.

Background:Glutamate (Glu) is of great interest in biomedical research. It is considered a biomarker in diabetes, which may potentially contribute to the development of autism in genetically vulnerable human populations, and it is found in relation to advanced glycation end products (AGEs) [1]. Additionally, Glu plays an active role in the function of ligand-gated ion channel glutamate receptors, chloride channels capable of filtering glutamate, as well as Potassium (K+)-channel [2]. Glu attains α [3] and β [4] crystal forms and Cβ-CH2 show asymmetric 1H signal pattern in NMR spectra.Objectives:The current study was undertaken to understand the signal patterns of Cβ-CH2 in Glu of the smallest dipeptide, Glycylglutamic Acid (GlyGlu), as well as the order, and planarity of the amide bond in the molecule.Materials and Methods:NMR spectra of GlyGlu were measured in D2O to deduce 1H and 13C chemical shifts and coupling constants. GlyGlu was crystallized from MeOH and the structure was determined by single crystal X-ray diffraction techniques.Results:The sidechain of Glu in the dipeptide dissimilates the β form. The amino group of Gly (Glycine) is protonated and exhibits hydrogen bonding with the main chain carboxylate group of a symmetry-related Glu that is deprotonated in the crystal packing of GlyGlu. The deprotonated main chain carboxylate of Glu is also in hydrogen-bonding distance from the side chain carboxylic acid group that is in the protonated form of a symmetry-related Glu of the dipeptide. The Cβ-CH2 geminal protons on the side chain of Glu have different chemical shifts and splitting pattern in 1H NMR reflecting their dissymmetric environment.Conclusion:The results reported will be useful for monitoring changes that Glu and/or molecules in connection to Glu may undergo in in vivo, in situ, and in vitro conditions. This provides a valuable metric which will enable the examination of the metabolites relevant to the detection and diagnosis of disease or developmental conditions, as well as scrutinizing the effectiveness of treatment options.

SYNTHESIS OF PROBE MOLECULES, 6-(DIMETHYLAMINO)-2-PHENYLISOINDOLIN-1-ONES, FOR MECHANISTIC STUDIES OF FIREFLY LUCIFERASE INHIBITION.

Firefly luciferase is used in high-throughput screening based on the detection of chemiluminescence. It catalyzes an esterification reaction of luciferin with adenosine 5'-triphosphate (ATP) followed by decarbonylation with oxygen and concomitance of light. Previously, we reported that firefly luciferase also possesses acyl-CoA synthetase activity and catalyzes an aromatic carboxylic acid group of F-53, using ATP, Mg2+ and coenzyme A (CoA), to produce F-53 covalently attached to active-site lysine-529 residue of firefly luciferase through the formation of an amide group. The amidation of lysine-529 resulted in a deactivation of luciferase. In order to probe firefly luciferase inhibition's mechanism, we synthesized two probe molecules 1 and 2, mimicking F-53. Molecule 1 contains an azido-appended side chain in the aromatic ring of F-53, while 2 possesses an azido and a carboxylic acid group appended side chains. Both synthetic schemes are readily amenable to large-scale syntheses. Molecule 1 was made from 2-allylaniline, which was derived from a thermal-induced aromatic-Claisen rearrangement of N-allylaniline. The azido-appended side chain of 2 was installed from a Horner-Wadsworth-Emmons reaction and the carboxylic acid side chain from a Sonogashira reaction.

Stereoselective Oxidative Bioconjugation of Amino Acids and Oligopeptides to Aldehydes.

The first stereoselective, near-equimolar, and metal-free oxidative bioconjugation of amino acids and oligopeptides to aldehydes is presented. Based on a newly developed organocatalytic oxidative concept, the C-terminal and side-chain carboxylic acid functionalities of amino acids and oligopeptides are shown to couple in a stereoselective manner to α-branched aldehydes catalyzed by a chiral primary amine and a quinone as oxidizing agent. The oxidative coupling generally proceeds in high yield. For aspartic acid, selective coupling of the side-chain, or the C-terminal carboxylic acid, is demonstrated depending on the protection strategy. The stereoselective, oxidative bioconjugation concept is extended to a series of oligopeptides where coupling to carboxylic acid functionalities is presented. Bioorthogonal linker molecules for further functionalization are obtained by merging the oxidative coupling strategy with the click concept. It is demonstrated that the configuration of the new stereocenter is determined exclusively by the organocatalyst.

Cellular attachment behavior on biodegradable polymer surface immobilizing endothelial cell-specific peptide

Small-caliber artificial blood vessels with inner diameters of smaller than 4 mm have not been put into practical use because of early thrombus formation and graft occlusion. To realize small-caliber artificial blood vessels with anti-thrombus property and long-term patency, one of the promising approaches is endothelialization of the lumen by tissue engineering approaches. Integrin α4β1 on the endothelial cell membrane is known to act as a receptor for Arg-Glu-Asp-Val (REDV) tetra-peptide, and this peptide can be used as a specific ligand to introduce endothelial cell attachment onto the surfaces of polymer scaffold. In this study, biodegradable polymer surface immobilizing REDV peptide were prepared, and the specific attachment of endothelial cells on it was investigated as a preliminary study for tissue-engineered small-caliber blood vessels in a future application. We synthesized copolymer of ε-caprolactone and depsipeptide having reactive carboxylic acid side-chain groups (PGDCL), and REDV peptide was attached to the copolymer to give PGDCL-REDV. The attachment of human umbilical vein endothelial cells (HUVECs) were investigated for the blend polymer film prepared by mixing PGDCL and PGDCL-REDV. The obtained blend polymer films exhibited sequence- and cell-specific HUVECs attachment through REDV peptide recognition. This technique should be useful not only to obtain artificial blood vessels which induce endothelialization and but also to provide biodegradable scaffolds with specific ligands immobilized surfaces for tissue regeneration.

An Optical Steam Sterilization Sensor Based On a Dual-Responsive Supramolecular Cross-Linked Photonic Polymer.

An optical time–temperature steam sensor is presented based on the loss of structural color in a supramolecularly cross-linked cholesteric liquid crystal photonic coating. A gradual decrease in the selective reflection band is observed upon exposure to temperatures above 105 °C related to the cholesteric to isotropic transition temperature. The linear polymers with carboxylic acid side chains provide physical cross-linking through hydrogen bonding that allows a time–temperature-dependent order loss through the dynamic equilibrium between supramolecular dimer and free monomer states. Steam is accelerating the color loss, and autoclave experiments show that the photonic supramolecular polymer is applicable as a steam sterilization sensor for medical applications.