Biodegradable and biocompatible multi-arm star amphiphilic block copolymer as a carrier for hydrophobic drug delivery

Structurally nanoengineered antimicrobial peptide polymers: design, synthesis and biomedical applications

Antimicrobial resistance not only increases the contagiousness of infectious diseases but also a threat for the future as it is one of the health care concern around the globe. Conventional antibiotics are unsuccessful in combating chronic infections caused by multidrug-resistant (MDR) bacteria, therefore it is important to design and develop novel strategies to tackle this problems. Among various novel strategies, Structurally Nanoengineered Antimicrobial Peptide Polymers (SNAPPs) have been introduced in recent years to overcome this global health care issue and they are found to be more efficient in their performance. Many facile methods are adapted to synthesize complex SNAPPs with required dimensions and unique functionalities. Their unique characteristics and remarkable properties have been exploited for their immense applications in various fields including biomedicine, targeting therapies, gene delivery, bioimaging, and many more. This review article deals with its background, design, synthesis, mechanism of action, and wider applications in various fields of SNAPPs.

Linear and Branched Lactide Polymers for Targeted Drug Delivery Systems

Abstract

The review presents modern advances in the synthesis of biodegradable polymers based on lactide of various topologies and also analyzes the main methods for preparation of nanoparticles that show promise for the creation of targeted drug delivery systems.

Resveratrol-loaded nanomedicines for cancer applications

BACKGROUND

Resveratrol (3, 5, 4' -trihydroxystilbene), a natural polyphenol and phytoalexin, has drawn considerable attention in the past decade due to its wide variety of therapeutic activities such as anticancer, anti-inflammatory, and antioxidant properties. However, its poor water solubility, low chemical stability, and short biological half-life limit its clinical utility.

RECENT FINDINGS

Nanoparticles overcome the limitations associated with conventional chemotherapeutic drugs, such as limited availability of drugs to the tumor tissues, high systemic exposures, and consequent toxicity to healthy tissues. This review focuses on the physicochemical properties of resveratrol, the therapeutic potential of resveratrol nano-formulations, and the anticancer activity of resveratrol encapsulated nanoparticles on various malignancies such as skin, breast, prostate, colon, liver, ovarian, and lung cancers (focusing on both in vitro and in vivo studies).

CONCLUSIONS

Nanotechnology approaches have been extensively utilized to achieve higher solubility, improved oral bioavailability, enhanced stability, and controlled release of resveratrol. The resveratrol nanoparticles have markedly enhanced its anticancer activity both in vitro and in vivo, thus considering it as a potential strategy to fight various cancers.

Synthesis, Enzymatic Degradation, and Polymer-Miscibility Evaluation of Nonionic Antimicrobial Hyperbranched Polyesters with Indole or Isatin Functionalities

Most macromolecular antimicrobials are ionic and thus lack miscibility/compatibility with nonionic substrate materials. In this context, nonionic hyperbranched polyesters (HBPs) with indole or isatin functionality were rationally designed, synthesized, and characterized. Antimicrobial disk diffusion assay indicated that these HBPs showed significant antibacterial activity against 8 human pathogenic bacteria compared to small molecules with indole or isatin groups. According to DSC measurements, up to 20% indole-based HBP is miscible with biodegradable polyesters (polyhydroxybutyrate or polycaprolactone), which can be attributed to the favorable hydrogen bonding between the N–H moiety of indole and the C=O of polyesters. HBPs with isatin or methylindole were completely immiscible with the same matrices. None of the HBPs leaked out from plastic matrix after being immersed in water for 5 days. The incorporation of indole into HBPs as well as small molecules facilitated their enzymatic degradation with PETase from Ideonella sakaiensis, while isatin had a complex impact. Molecular docking simulations of monomeric molecules with PETase revealed different orientations of the molecules at the active site due to the presence of indole or isatin groups, which could be related to the observed different enzymatic degradation behavior. Finally, biocompatibility analysis with a mammalian cell line showed the negligible cytotoxic effect of the fabricated HBPs.

Biodegradable dendritic Boltorn™ nanoconstructs: A promising avenue for cancer theranostics

The family of Boltorn™ H40 dendrimers is an imperative subclass of hyperbranched biodegradable polymers (HBPs), which has received mounting attention as a result of its inimitable chemical, physical and biodegradable properties. These properties embrace three-dimensional dendrimeric nanoarchitecture to avert tanglement between polymer branches, adequate spatial cavities for increased encapsulation of guest molecules, good solubility as well as low viscosity to improve processability, and a huge number of surface functional groups for chemical manipulations. Similarly, low toxicity, non-immunogenicity, and natural biodegradation are significant and critical advantages in therapeutic applications as compared to other dendritic polymers. All these characteristics of Boltorn™ H40 are of pronounced importance for planning and developing advanced targeted cargo delivery carriers for cancer therapy. The present review highlights the applications of Boltorn™ H40 HBPs for the transport of chemotherapeutic agents to manage various types of cancers.

Design of an amphiphilic hyperbranched core/shell-type polymeric nanocarrier platform for drug delivery

An amphiphilic core/shell-type polymer-based drug carrier system (HPAE- PCL-b -MPEG), composed of hyperbranched poly(aminoester)-based polymer (HPAE) as the core building block and poly(ethylene glycol)-b - poly(ε-caprolactone) diblock polymers (MPEG-b -PCL) as the shell building block, was designed. The synthesized polymers were characterized with FTIR, 1 H NMR, 13 C NMR, and GPC analysis. Monodisperse HPAE-PCL-b - MPEG nanoparticles with dimensions of < 200 nm and polydispersity index of < 0.5 were prepared by nanoprecipitation method and characterized with SEM, particle size, and zeta potential analysis. 5-Fluorouracil was encapsulated within HPAE-PCL-b -MPEG nanoparticles. In vitro drug release profiles and cytotoxicity of blank and 5-fluorouracil-loaded nanoparticles were examined against the human colon cancer HCT116 cell line. All results suggest that HPAE-PCL-b - MPEG nanoparticles offer an alternative and effective drug nanocarrier system for drug delivery applications.

Advances in amphiphilic hyperbranched copolymers with an aliphatic hyperbranched 2,2-bis(methylol)propionic acid-based polyester core

Amphiphilic hyperbranched copolymers with an aliphatic hyperbranched 2,2-bis(methylol)propionic acid-based polyester core were highlighted.

Biomimetic surface modification of discoidal polymeric particles

The rationale for the design of drug delivery nanoparticles is traditionally based on co-solvent self-assembly following bottom-up approaches or in combination with top-down approaches leading to tailored physiochemical properties to regulate biological responses. However, the optimal design and control of material properties to achieve specific biological responses remain the central challenge in drug delivery research. Considering this goal, we herein designed discoidal polymeric particles (DPPs) whose surfaces are re-engineered with isolated red blood cell (RBC) membranes to tailor their pharmacokinetics. The RBC membrane-coated DPPs (RBC-DPPs) were found to be biocompatible in cell-based in vitro experiments and exhibited extended blood circulation half-life. They also demonstrated unique kinetics at later time points in a mouse model compared to that of bare DPPs. Our results suggested that the incorporation of biomimicry would enable the biomimetic particles to cooperate with systems in the body such as cells and biomolecules to achieve specific biomedical goals.

Star-Graft Quarterpolymer-Based Polymersomes as Nanocarriers for Co-Delivery of Hydrophilic/Hydrophobic Chemotherapeutic Agents

We report the fabrication of polymersomes, using as building blocks star-graft quarterpolymers, composed of hydrophobic polystyrene and pH-sensitive poly(2-vinylpyridine)-b-poly(acrylic acid) (P2VP-b-PAA) arms, emanated from a common nodule, enriched by thermosensitive poly(N-isopropylacrylamide) grafts covalently bonded on the PAA block-arms. These multicompartmental polymersomes were evaluated as nanocarriers for the encapsulation and controlled co-delivery of doxorubicin (hydrophilic) and paclitaxel (hydrophobic) chemotherapeutic agents. The polymersomes can load these drugs in different compartments and can efficiently be internalized in the human lung adenocarcinoma epithelial cells, delivering their cargo and inducing high cell apoptosis. The release kinetics of both anticancer agents was controlled differently by the environmental conditions (pH and temperature). Enhanced release was observed at the acidic pH 6.0 and under physiological temperature (37 °C). At the same total drug level, co-delivery of these drugs with the polymersomes caused enhanced cytotoxicity and induced significantly higher cell apoptosis in the cancer cell line compared to the polymersomes loaded with either of the two drugs.

Star polymer-based unimolecular micelles and their application in bio-imaging and diagnosis

As a novel kind of polymer with covalently linked core-shell structure, star polymers behave in nanostructure in aqueous medium at all concentration range, as unimolecular micelles at high dilution condition and multi-micelle aggregates in other situations. The unique morphologies endow star polymers with excellent stability and functions, making them a promising platform for bio-application. A variety of functions including imaging and therapeutics can be achieved through rational structure design of star polymers, and the existence of plentiful end-groups on shell offers the opportunity for further modification. In the last decades, star polymers have become an attracting platform on fabrication of novel nano-systems for bio-imaging and diagnosis. Focusing on the specific topology and physicochemical properties of star polymers, we have reviewed recent development of star polymer-based unimolecular micelles and their bio-application in imaging and diagnosis. The main content of this review summarizes the synthesis of integrated architecture of star polymers and their self-assembly behavior in aqueous medium, focusing especially on the recent advances on their bio-imaging application and diagnosis use. Finally, we conclude with remarks and give some outlooks for further exploration in this field.

Doxorubicin-Loaded Unimolecular Micelle-Stabilized Gold Nanoparticles as a Theranostic Nanoplatform for Tumor-Targeted Chemotherapy and Computed Tomography Imaging

Current research is mainly trending toward addressing the development of multifunctional nanocarriers that could precisely reach disease sites, release drugs in a controlled-manner, and act as an imaging agent for both diagnosis and targeted therapy. In this study, a pH-sensitive theranostic nanoplatform as a promising dual-functional nanovector for tumor therapy and computed tomography (CT) imaging was developed. The 21-arm star-like triblock polymer of β-cyclodextrin-{poly(ε-caprolactone)-poly(2-aminoethyl methacrylate)-poly[poly(ethylene glycol) methyl ether methacrylate]}₂₁ [β-CD-(PCL-PAEMA-PPEGMA)₂₁] with stable unimolecular micelles formed in aqueous solution was first synthesized by combined ROP with ARGET ATRP techniques and then was used as a template for fabricating gold nanoparticles (AuNPs) with uniform sizes and excellent colloidal stability in situ followed by the encapsulation of doxorubicin (DOX) with maximum entrapment efficiency up to 60% to generate the final product β-CD-(PCL-PAEMA-PPEGMA)₂₁/AuNPs/DOX. Furthermore, dissipative particle dynamics (DPD) simulations revealed further details of the formation process of unimolecular micelles and the morphologies and distributions of AuNPs and DOX. Almost 80% of DOX was released in 120 h in an acidic tumoral environment in an in vitro drug release experiment, and the experiments both in vitro and in vivo demonstrated the fact that β-CD-(PCL-PAEMA-PPEGMA)₂₁/AuNPs/DOX exhibited similar antitumor efficacy to free DOX and effective CT imaging performance. Therefore, we believe this structurally stable unimolecular micelle-based nanoplatform synergistically integrated with anticancer drug delivery and CT imaging capabilities hold great promise for future cancer theranostics.

pH-responsive unimolecular micelle-gold nanoparticles-drug nanohybrid system for cancer theranostics

The development of an in situ formed pH-responsive theranostic nanocomposite for anticancer drug delivery and computed tomography (CT) imaging was reported. β-cyclodextrin-{poly(lactide)-poly(2-(dimethylamino) ethyl methacrylate)-poly[oligo(2-ethyl-2-oxazoline)methacrylate]}₂₁ [β-CD-(PLA-PDMAEMA-PEtOxMA)₂₁] unimolecular micelles served as a template for the in situ formation of gold nanoparticles (GNPs) and the subsequent encapsulation of doxorubicin (DOX). The formation of unimolecular micelles, microstructures and the distributions of GNPs and DOX were investigated through the combination of experiments and dissipative particle dynamics (DPD) simulations. β-CD-(PLA-PDMAEMA-PEtOxMA)₂₁ formed spherical unimolecular micelles in aqueous solution within a certain range of polymer concentrations. GNPs preferentially distributed in the PDMAEMA area. The maximum wavelength (λ_max) and the size of GNPs increased with increasing concentration of HAuCl₄. DOX preferentially distributed in the PDMAEMA mesosphere, but penetrated the inner PLA core with increasing DOX concentration. DOX-loaded micelles with 41-61% entrapment efficiency showed fast release (88% after 102h) under acidic tumor conditions. Both in vitro and in vivo experiments revealed superior anticancer efficacy and effective CT imaging properties for β-CD-(PLA-PDMAEMA-PEtOxMA)₂₁/Au/DOX. We conclude that the reported unimolecular micelles represent a class of versatile smart nanocarriers for theranostic application.

STATEMENT OF SIGNIFICANCE

Developing polymeric nanoplatforms as integrated theranostic vehicles for improving cancer diagnostics and therapy is an emerging field of much importance. This article aims to develop an in situ formed pH-responsive theranostic nanocomposite for anticancer drug delivery and computed tomography (CT) imaging. Specific emphases is on structure-properties relationship. There is a sea of literature on polymeric drug nanocarriers, and a couple of polymer-stabilized gold nanoparticles (GNPs) systems for cancer diagnosis are also known. However, to our knowledge, there has been no report on polymeric unimolecular micelles capable of dual loading of GNPs without external reducing agents and anticancer drugs for cancer diagnosis and treatment. To this end, the target of the current work was to develop an in situ formed nanocarrier, which actively dual wrapped CT contrast agent GNPs and hydrophobic anticancer drug doxorubicin (DOX), achieving high CT imaging and antitumor efficacy under in vitro and in vivo acid tumor condition. Meanwhile, by taking advantage of dissipative particle dynamics (DPD) simulation, we further obtained the formation process and mechanism of unimolecular micelles, and detailed distributions and microstructures of GNPs and DOX on unimolecular micelles. Taken together, our results here provide insight and guidance for the design of more effective nanocarriers for cancer theranostic application.

"Bottom-up" Construction of Multi-Polyprodrug-Arm Hyperbranched Amphiphiles for Cancer Therapy

Despite the great advantages of polymer-drug conjugates (PDC) in cancer therapy, control of the drug loading site and degree via a facile approach remains a great challenge. Herein, by combining the controllability of the "bottom-up" strategy and the stability of multiarm hyperbranched amphiphiles, we have developed novel multi-polyprodrug-arm hyperbranched amphiphiles (H40-star-(PHCPTMA-b-PMPC), hPCM) via reversible addition-fragmentation chain transfer (RAFT) polymerization for cancer therapy. The hPCM was constructed via two-step polymerization of an acid-labile prodrug monomer and a zwitterionic monomer, respectively. By using an H40 macroRAFT agent, 10-hydroxycamptothecine (HCPT) prodrug monomers were directly polymerized via the "bottom-up" strategy as a polyprodrug-arm inner-shell of hPCM with homogeneous drug distribution. The drug loading content can be facilely tuned through variation of the feed ratio of HCPTMA/H40 macroRAFT agent. Finally, the poly-zwitterionic hydrophilic outer-shell of hPCM was formed by RAFT polymerization of zwitterionic monomer to ensure preferable biocompatibility. By dissolving in dilute solution, unimolecular micelles of hPCM can be obtained, which endow desirable stability for the micelles. The effective cellular internalization, extended blood retention time, considerable accumulation in tumor tissue, and excellent anticancer activity of the hPCM micelles have been evaluated both in vitro and in vivo. This novel multi-polyprodrug-arm hyperbranched amphiphile constructed via the "bottom-up" strategy may open up new horizons for exploring next-generation PDC-based drug delivery systems.

Branched polyesters: Preparative strategies and applications

In the last 20years, the availability of precision chemical tools (e.g. controlled/living polymerizations, 'click' reactions) has determined a step change in the complexity of both the macromolecular architecture and the chemical functionality of biodegradable polyesters. A major part in this evolution has been played by the possibilities that controlled macromolecular branching offers in terms of tailored physical/biological performance. This review paper aims to provide an updated overview of preparative techniques that derive hyperbranched, dendritic, comb, grafted polyesters through polycondensation or ring-opening polymerization mechanisms.

Star Polymers

Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

PEG based anti-cancer drug conjugated prodrug micelles for the delivery of anti-cancer agents

Development of polymer prodrug conjugates has evolved recently in the nano-medicine field for cancer diagnosis and treatment. This review focuses on the development of different types of PEG based polymer drug conjugates used for the delivery of anti-cancer agents.

Core Cross-linked Star Polymers for Temperature/pH Controlled Delivery of 5-Fluorouracil

RAFT polymerization with cross-linking was used to prepare core cross-linked star polymers bearing temperature sensitive arms. The arms consisted of a diblock copolymer containingN-isopropylacrylamide (NIPAAm) and 4-methacryloyloxy benzoic acid (4MBA) in the temperature sensitive block and poly(hexyl acrylate) forming the second hydrophobic block, while ethyleneglycol dimethacrylate was used to form the core. The acid comonomer provides pH sensitivity to the arms and also increases the transition temperature of polyNIPAAm to values in the range of 40 to 46°C. Light scattering and atomic force microscopy studies suggest that loose core star polymers were obtained. The star polymers were loaded with 5-fluorouracil (5-FU), an anticancer agent, in values of up to 30 w/w%.In vitrorelease experiments were performed at different temperatures and pH values, as well as with heating and cooling temperature cycles. Faster drug release was obtained at 42°C or pH 6, compared to normal physiological conditions (37°C, pH 7.4). The drug carriers prepared acted as nanopumps changing the release kinetics of 5-FU when temperatures cycles were applied, in contrast with release rates at a constant temperature. The prepared core cross-linked star polymers represent advanced drug delivery vehicles optimized for 5-FU with potential application in cancer treatment.

Stable and pH-responsive polyamidoamine based unimolecular micelles capped with a zwitterionic polymer shell for anticancer drug delivery

Zwitterionic dendrimer based unimolecular micelles for anticancer drug delivery were prepared, exhibiting excellent stability in complex biological media.

Recent development of unimolecular micelles as functional materials and applications

Unimolecular micelles have high functionalities, encapsulation capabilities and site specific confinement abilities in various applications.

Host–guest binding motifs based on hyperbranched polymers

Host–guest systems based on hyperbranched polymers together with their unique properties and various applications have been summarized.

pH-sensitive drug release of star-shaped micelles with OEG brush corona

We presented herein pH-mediated drug release behaviors from a generally recognized “pH-insensitive” star-shaped PCL-POEGMA micelles, which were attributed primarily to the hydrophilic corona of OEG brushes.

Disulfide-Functionalized Unimolecular Micelles as Selective Redox-Responsive Nanocarriers

Redox-sensitive hyperbranched dendritic-linear polymers (HBDLPs) were prepared and stabilized individually as unimolecular micelles with diameters in the range 25-40 nm. The high molecular weight (500-950 kDa), core-shell amphiphilic structures were synthesized through a combination of self-condensing vinyl copolymerization (SCVCP) and atom transfer radical polymerization (ATRP). Cleavable disulfide bonds were introduced, either in the backbone, or in pendant groups, of the hyperbranched core of the HBDLPs. By triggered reductive degradation, the HBDLPs showed up to a 7-fold decrease in molecular weight, and the extent of degradation was tuned by the amount of incorporated disulfides. The HBDLP with pendant disulfide-linked functionalities in the hyperbranched core was readily postfunctionalized with a hydrophobic dye, as a mimic for a drug. An instant release of the dye was observed as a response to a reductive environment similar to the one present intracellularly. The proposed strategy shows a facile route to highly stable unimolecular micelles, which attractively exhibit redox-responsive degradation and cargo release properties.

A novel biodegradable hyperbranched polyester prepared from cellulose and tyrosine via the synthesis route of glycopeptides

A novel hyperbranched polyester has been prepared through the polycondensation of an AB_n-type monomer, which was synthesized from a glycopeptide reaction.

Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier

In this paper, a novel, multifunctional polymer nanocarrier was designed to provide adequate volume for high drug loading, to afford a multiregion encapsulation ability, and to achieve controlled drug release. An amphiphilic, triblock polymer (ABC) with hyperbranched polycarbonsilane (HBPCSi) and β-cyclodextrin (β-CD) moieties were first synthesized by the combination of a two-step reversible addition-fragmentation transfer polymerization into a pseudo-one-step hydrosilylation and quaternization reaction. The ABC then self-assembled into stable micelles with a core–shell structure in aqueous solution. These resulting micelles are multifunctional nanocarriers which possess higher drug loading capability due to the introduction of HBPCSi segments and β-CD moieties, and exhibit controlled drug release based on the diffusion release mechanism. The novel multifunctional nanocarrier may be applicable to produce highly efficient and specialized delivery systems for drugs, genes, and diagnostic agents.

Synthesis and therapeutic applications of biocompatible or biodegradable hyperbranched polymers

The recent progress in the synthesis, modifications and therapeutic applications of biocompatible or biodegradable hyperbranched polymers has been reviewed.

Theranostic unimolecular micelles based on brush-shaped amphiphilic block copolymers for tumor-targeted drug delivery and positron emission tomography imaging

Brush-shaped amphiphilic block copolymers were conjugated with a monoclonal antibody against CD105 (i.e., TRC105) and a macrocyclic chelator for (64)Cu-labeling to generate multifunctional theranostic unimolecular micelles. The backbone of the brush-shaped amphiphilic block copolymer was poly(2-hydroxyethyl methacrylate) (PHEMA) and the side chains were poly(L-lactide)-poly(ethylene glycol) (PLLA-PEG). The doxorubicin (DOX)-loaded unimolecular micelles showed a pH-dependent drug release profile and a uniform size distribution. A significantly higher cellular uptake of TRC105-conjugated micelles was observed in CD105-positive human umbilical vein endothelial cells (HUVEC) than nontargeted micelles due to CD105-mediated endocytosis. In contrast, similar and extremely low cellular uptake of both targeted and nontargeted micelles was observed in MCF-7 human breast cancer cells (CD105-negative). The difference between the in vivo tumor accumulation of (64)Cu-labeled TRC105-conjugated micelles and that of nontargeted micelles was studied in 4T1 murine breast tumor-bearing mice, by serial positron emission tomography (PET) imaging and validated by biodistribution studies. These multifunctional unimolecular micelles offer pH-responsive drug release, noninvasive PET imaging capability, together with both passive and active tumor-targeting abilities, thus making them a desirable nanoplatform for cancer theranostics.

pH-responsive flower-like micelles constructed via oxime linkage for anticancer drug delivery

pH-responsive flower-like micelles from triblock copolymer with oxime linkage were developed for the anticancer drug delivery.

Impedimetric aptasensor for ochratoxin A determination based on Au nanoparticles stabilized with hyper-branched polymer

An impedimetric aptasensor for ochratoxin A (OTA) detection has been developed on the base of a gold electrode covered with a new modifier consisting of electropolymerized Neutral Red and a mixture of Au nanoparticles suspended in the dendrimeric polymer Botlorn H30®. Thiolated aptamer specific to OTA was covalently attached to Au nanoparticles via Au-S bonding. The interaction of the aptamer with OTA induced the conformational switch of the aptamer from linear to guanine quadruplex form followed by consolidation of the surface layer and an increase of the charge transfer resistance. The aptasensor makes it possible to detect from 0.1 to 100 nM of OTA (limit of detection: 0.02 nM) in the presence of at least 50 fold excess of ochratoxin B. The applicability of the aptasensor for real sample assay was confirmed by testing spiked beer samples. The recovery of 2 nM OTA was found to be 70% for light beer and 78% for dark beer.

Oligomerization of 10,16-dihydroxyhexadecanoic acid and methyl 10,16-dihydroxyhexadecanoate catalyzed by lipases

The main monomer of tomato cuticle, 10,16-dihydroxyhexadecanoic acid (10,16-DHPA) and its methyl ester derivative (methyl-10,16-dihydroxyhexadecanote; methyl-10,16-DHHD), were used to study their oligomerization reactions catalyzed by five lipases: Candida antarctica lipase B (CAL-B), Rhizomucor miehei lipase (RM), Thermomyces lanuginosus lipase (TL), Pseudomonas cepacia lipase (PCL) and porcine pancreatic lipase (PPL). For 10,16-DHPA, optimum yields were obtained at 60 °C using toluene and 2-methyl-2-butanol (2M2B) as solvent, while for methyl-10,16-DHHD the bests yields were obtained in toluene and acetonitrile. Both reactions leaded to linear polyesters according to the NMR and FT-IR analysis, and there was no data indicating the presence of branched polymers. Using optimized conditions, poly(10,16-DHPA) and poly(methyl-10,16-DHHD) with Mw = 814 and Mn = 1,206 Da, and Mw = 982 and Mn = 860 Da, respectively, were formed according to their MALDI-TOF MS and ESI-MS data. The self-assembly of the polyesters obtained were analyzed by AFM.