Eric Andrew Appel
Assistant Professor of Material Science and Engineering and, by courtesy, of Bioengineering
Materials Science and Engineering
Web page: http://supramolecularbiomaterials.com
Bio
Eric A. Appel is an Assistant Professor of Materials Science & Engineering at Stanford University. He received his BS in Chemistry and MS in Polymer Science from Cal Poly, San Luis Obispo. Eric performed his MS thesis research with Robert D. Miller and James L. Hedrick at the IBM Almaden Research Center in San Jose, CA. He then obtained his PhD in Chemistry working in the lab of Dr. Oren A. Scherman in the Melville Laboratory for Polymer Synthesis at the University of Cambridge. His PhD research focused on the preparation of dynamic and stimuli-responsive supramolecular polymeric materials. For his PhD work, Eric was the recipient of the Jon Weaver PhD prize from the Royal Society of Chemistry and a Graduate Student Award from the Materials Research Society. Upon graduating from Cambridge in 2012, he was awarded a National Research Service Award from the NIH (NIBIB) and pursued a Wellcome Trust Postdoctoral Fellowship at MIT working with Robert S. Langer on the development of supramolecular biomaterials for drug delivery and tissue engineering. During his post-doctoral work, he received a Margaret A. Cunningham Immune Mechanisms in Cancer Research Award. He recently received a Terman Faculty Fellowship from the School of Engineering at Stanford University.
Academic Appointments
-
Assistant Professor, Materials Science and Engineering
-
Assistant Professor (By courtesy), Bioengineering
-
Member, Bio-X
-
Member, Cardiovascular Institute
-
Faculty Fellow, Stanford ChEM-H
Professional Education
-
Postdoc, MIT, Bioengineering
-
Ph.D., University of Cambridge, Chemistry (2012)
-
M.S., Cal Poly, SLO, Polymer Science (2008)
-
B.S., Cal Poly, SLO, Chemistry (2008)
Current Research and Scholarly Interests
The underlying theme of the Appel Lab at Stanford University integrates concepts and approaches from supramolecular chemistry, natural/synthetic materials, and biology. We aim to develop supramolecular biomaterials that exploit a diverse design toolbox and take advantage of the beautiful synergism between physical properties, aesthetics, and low energy consumption typical of natural systems. Our vision is to use these materials to solve fundamental biological questions and to engineer advanced healthcare solutions.
2017-18 Courses
- Materials Science Colloquium
MATSCI 230 (Win, Spr) - Organic and Biological Materials
MATSCI 190, MATSCI 210 (Spr) - Soft Matter in Biomedical Devices, Microelectronics, and Everyday Life
BIOE 158, CHEMENG 160, MATSCI 158 (Win) -
Independent Studies (7)
- Bioengineering Problems and Experimental Investigation
BIOE 191 (Win, Spr) - Directed Investigation
BIOE 392 (Aut, Win, Spr, Sum) - Master's Research
MATSCI 200 (Aut, Win, Spr) - Ph.D. Research
MATSCI 300 (Aut, Win, Spr, Sum) - Practical Training
MATSCI 299 (Sum) - Undergraduate Independent Study
MATSCI 100 (Sum) - Undergraduate Research
MATSCI 150 (Sum)
- Bioengineering Problems and Experimental Investigation
-
Prior Year Courses
2016-17 Courses
- Materials Science Colloquium
MATSCI 230 (Win, Spr) - Organic and Biological Materials
MATSCI 190, MATSCI 210 (Spr) - Soft Matter in Biomedical Devices, Microelectronics, and Everyday Life
BIOE 158, CHEMENG 160, MATSCI 158 (Win)
2015-16 Courses
- Organic and Biological Materials
MATSCI 190, MATSCI 210 (Spr)
- Materials Science Colloquium
Stanford Advisees
-
Postdoctoral Faculty Sponsor
Eneko Axpe Iza, Hector Lopez Hernandez -
Doctoral Dissertation Advisor (AC)
Doreen Chan -
Postdoctoral Research Mentor
Eneko Axpe Iza, Hector Lopez Hernandez
All Publications
-
Mixed Reversible Covalent Crosslink Kinetics Enable Precise, Hierarchical Mechanical Tuning of Hydrogel Networks
ADVANCED MATERIALS
2017; 29 (19)
Abstract
Hydrogels play a central role in a number of medical applications and new research aims to engineer their mechanical properties to improve their capacity to mimic the functional dynamics of native tissues. This study shows hierarchical mechanical tuning of hydrogel networks by utilizing mixtures of kinetically distinct reversible covalent crosslinks. A methodology is described to precisely tune stress relaxation in PEG networks formed from mixtures of two different phenylboronic acid derivatives with unique diol complexation rates, 4-carboxyphenylboronic acid, and o-aminomethylphenylboronic acid. Gel relaxation time and the mechanical response to dynamic shear are exquisitely controlled by the relative concentrations of the phenylboronic acid derivatives. The differences observed in the crossover frequencies corresponding to pKa differences in the phenylboronic acid derivatives directly connect the molecular kinetics of the reversible crosslinks to the macroscopic dynamic mechanical behavior. Mechanical tuning by mixing reversible covalent crosslinking kinetics is found to be independent of other attributes of network architecture, such as molecular weight between crosslinks.
View details for DOI 10.1002/adma.201605947
View details for Web of Science ID 000401170600014
View details for PubMedID 28295624
-
Single-Chain Polymeric Nanocarriers: A Platform for Determining Structure-Function Correlations in the Delivery of Molecular Cargo
BIOMACROMOLECULES
2017; 18 (4): 1434-1439
Abstract
There has been growing interest in producing stable, biocompatible nanocarriers for the controlled delivery of therapeutics. With micelles, it remains a challenge to predict a priori the size, aggregation number, and functionality of the self-assembled aggregates. Utilizing controlled radical polymerization techniques, we have prepared tunable high molecular weight amphiphilic comb copolymers that self-assemble into unimolecular "micelle-like" nanocarriers of predictable size and functionality. Excellent control over self-assembly behavior and structure allows for systematic determination of the role of important polymeric material properties (i.e., glass transition) on the release of model therapeutics while simultaneously controlling for size, dispersity, structural, and functionality effects. Moreover, these single-chain polymeric nanocarriers represent a class of drug delivery systems allowing for interrogation of the limitations of standard methods for characterization of micellar aggregates.
View details for DOI 10.1021/acs.biomac.7b00249
View details for Web of Science ID 000399061100040
View details for PubMedID 28263572
- Engineering the Mechanical Properties of Polymer Networks with Precise Doping of Primary Defects ACS Applied Materials and Interfaces 2017; 9: 42217-42224
- Synthesis and Biological Evaluation of Ionizable Lipid Materials for the In Vivo Delivery of Messenger RNA to B Lymphocytes Advanced Materials 2017; 29: e1606944
- Distinguishing the Respective Mechanical Contributions of Polymer and Supramolecular Dynamics in Transiently Crosslinked Polymeric Networks Polymer Chemistry 2017; 8: 5336-5343
- Decoupled Associative and Dissociative Processes in Strong yet Highly Dynamic Host-Guest Complexes Journal of the American Chemical Society 2017; 139: 12985-12993
- Supramolecular Polymeric Biomaterials Biomaterials Science 2017; 6: 10-37
- Mechanistic understanding of in vivo protein corona formation on polymeric nanoparticles and impact on pharmacokinetics Nature Communication 2017; 8: e777
-
Scalable manufacturing of biomimetic moldable hydrogels for industrial applications
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2016; 113 (50): 14255-14260
Abstract
Hydrogels are a class of soft material that is exploited in many, often completely disparate, industrial applications, on account of their unique and tunable properties. Advances in soft material design are yielding next-generation moldable hydrogels that address engineering criteria in several industrial settings such as complex viscosity modifiers, hydraulic or injection fluids, and sprayable carriers. Industrial implementation of these viscoelastic materials requires extreme volumes of material, upwards of several hundred million gallons per year. Here, we demonstrate a paradigm for the scalable fabrication of self-assembled moldable hydrogels using rationally engineered, biomimetic polymer-nanoparticle interactions. Cellulose derivatives are linked together by selective adsorption to silica nanoparticles via dynamic and multivalent interactions. We show that the self-assembly process for gel formation is easily scaled in a linear fashion from 0.5 mL to over 15 L without alteration of the mechanical properties of the resultant materials. The facile and scalable preparation of these materials leveraging self-assembly of inexpensive, renewable, and environmentally benign starting materials, coupled with the tunability of their properties, make them amenable to a range of industrial applications. In particular, we demonstrate their utility as injectable materials for pipeline maintenance and product recovery in industrial food manufacturing as well as their use as sprayable carriers for robust application of fire retardants in preventing wildland fires.
View details for DOI 10.1073/pnas.1618156113
View details for Web of Science ID 000389696700044
View details for PubMedID 27911849
View details for PubMedCentralID PMC5167152
-
Supramolecular PEGylation of biopharmaceuticals
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2016; 113 (50): 14189-14194
Abstract
The covalent modification of therapeutic biomolecules has been broadly explored, leading to a number of clinically approved modified protein drugs. These modifications are typically intended to address challenges arising in biopharmaceutical practice by promoting improved stability and shelf life of therapeutic proteins in formulation, or modifying pharmacokinetics in the body. Toward these objectives, covalent modification with poly(ethylene glycol) (PEG) has been a common direction. Here, a platform approach to biopharmaceutical modification is described that relies on noncovalent, supramolecular host-guest interactions to endow proteins with prosthetic functionality. Specifically, a series of cucurbit[7]uril (CB[7])-PEG conjugates are shown to substantially increase the stability of three distinct protein drugs in formulation. Leveraging the known and high-affinity interaction between CB[7] and an N-terminal aromatic residue on one specific protein drug, insulin, further results in altering of its pharmacological properties in vivo by extending activity in a manner dependent on molecular weight of the attached PEG chain. Supramolecular modification of therapeutic proteins affords a noncovalent route to modify its properties, improving protein stability and activity as a formulation excipient. Furthermore, this offers a modular approach to append functionality to biopharmaceuticals by noncovalent modification with other molecules or polymers, for applications in formulation or therapy.
View details for DOI 10.1073/pnas.1616639113
View details for Web of Science ID 000389696700033
View details for PubMedID 27911829
-
Injectable and Glucose-Responsive Hydrogels Based on Boronic Acid-Glucose Complexation
LANGMUIR
2016; 32 (34): 8743-8747
Abstract
Injectable hydrogels have been widely used for a number of biomedical applications. Here, we report a new strategy to form an injectable and glucose-responsive hydrogel using the boronic acid-glucose complexation. The ratio of boronic acid and glucose functional groups is critical for hydrogel formation. In our system, polymers with 10-60% boronic acid, with the balance being glucose-modified, are favorable to form hydrogels. These hydrogels are shear-thinning and self-healing, recovering from shear-induced flow to a gel state within seconds. More importantly, these polymers displayed glucose-responsive release of an encapsulated model drug. The hydrogel reported here is an injectable and glucose-responsive hydrogel constructed from the complexation of boronic acid and glucose within a single component polymeric material.
View details for DOI 10.1021/acs.langmuir.5b04755
View details for Web of Science ID 000382513900022
View details for PubMedID 27455412
View details for PubMedCentralID PMC5242094
-
Bioinspired Alkenyl Amino Alcohol Ionizable Lipid Materials for Highly Potent In Vivo mRNA Delivery
ADVANCED MATERIALS
2016; 28 (15): 2939-2943
Abstract
Thousands of human diseases could be treated by selectively controlling the expression of specific proteins in vivo. A new series of alkenyl amino alcohol (AAA) ionizable lipid nanoparticles (LNPs) capable of delivering human mRNA with unprecedented levels of in vivo efficacy is demonstrated. This study highlights the importance of utilizing synthesis tools in tandem with biological inspiration to understand and improve nucleic acid delivery in vivo.
View details for DOI 10.1002/adma.201505822
View details for Web of Science ID 000374336700011
View details for PubMedID 26889757
View details for PubMedCentralID PMC5245883
-
Supramolecular biomaterials
NATURE MATERIALS
2016; 15 (1): 13-26
View details for DOI 10.1038/NMAT4474
View details for Web of Science ID 000366690600014
- Injectable Self-Healing Glucose Responsive Hydrogels with pH-Regulated Mechanical Properties Advanced Materials 2016; 28: 86-91
-
Supramolecular biomaterials.
Nature materials
2015; 15 (1): 13-26
Abstract
Polymers, ceramics and metals have historically dominated the application of materials in medicine. Yet rationally designed materials that exploit specific, directional, tunable and reversible non-covalent interactions offer unprecedented advantages: they enable modular and generalizable platforms with tunable mechanical, chemical and biological properties. Indeed, the reversible nature of supramolecular interactions gives rise to biomaterials that can sense and respond to physiological cues, or that mimic the structural and functional aspects of biological signalling. In this Review, we discuss the properties of several supramolecular biomaterials, as well as their applications in drug delivery, tissue engineering, regenerative medicine and immunology. We envision that supramolecular biomaterials will contribute to the development of new therapies that combine highly functional materials with unmatched patient- and application-specific tailoring of both material and biological properties.
View details for DOI 10.1038/nmat4474
View details for PubMedID 26681596
-
Water soluble, biodegradable amphiphilic polymeric nanoparticles and the molecular environment of hydrophobic encapsulates: Consistency between simulation and experiment
POLYMER
2015; 79: 255-261
View details for DOI 10.1016/j.polymer.2015.10.008
View details for Web of Science ID 000365042500028
-
Formation of Cucurbit[8]uril-Based Supramolecular Hydrogel Beads Using Droplet-Based Microfluidics
BIOMACROMOLECULES
2015; 16 (9): 2743-2749
Abstract
Herein we describe the use of microdroplets as templates for the fabrication of uniform-sized supramolecular hydrogel beads, assembled by supramolecular cross-linking of functional biopolymers with the macrocyclic host molecule, cucurbit[8]uril (CB[8]). The microdroplets were formed containing diluted hydrogel precursors in solution, including the functional polymers and CB[8], in a microfluidic device. Subsequent evaporation of water from collected microdroplets concentrated the contents, driving the formation of the CB[8]-mediated host-guest ternary complex interactions and leading to the assembly of condensed three-dimensional polymeric scaffolds. Rehydration of the dried particles gave monodisperse hydrogel beads. Their equilibrium size was shown to be dependent on both the quantity of material loaded and the dimensions of the microfluidic flow focus. Fluorescein-labeled dextran was used to evaluate the efficacy of the hydrogel beads as a vector for controlled cargo release. Both passive, sustained release (hours) and triggered, fast release (minutes) of the FITC-dextran was observed, with the rate of sustained release dependent on the formulation. The kinetics of release was fitted to the Ritger-Peppas controlled release equation and shown to follow an anomalous (non-Fickian) transport mechanism.
View details for DOI 10.1021/acs.biomac.5b01048
View details for Web of Science ID 000361341700020
View details for PubMedID 26256409
-
Exploiting Electrostatic Interactions in Polymer-Nanoparticle Hydrogels
ACS MACRO LETTERS
2015; 4 (8): 848-852
View details for DOI 10.1021/acsmacrolett.5b00416
View details for Web of Science ID 000359891200009
-
A Facile Method for the Stain-Free Visualization of Hierarchical Structures with Electron Microscopy
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
2015; 53 (7): 842-845
View details for DOI 10.1002/pola.27517
View details for Web of Science ID 000350278400002
-
Non-Cell-Adhesive Substrates for Printing of Arrayed Biomaterials
ADVANCED HEALTHCARE MATERIALS
2015; 4 (4): 501-505
Abstract
Cellular microarrays have become extremely useful in expediting the investigation of large libraries of (bio)materials for both in vitro and in vivo biomedical applications. An exceedingly simple strategy is developed for the fabrication of non-cell-adhesive substrates supporting the immobilization of diverse (bio)material features, including both monomeric and polymeric adhesion molecules (e.g., RGD and polylysine), hydrogels, and polymers.
View details for DOI 10.1002/adhm.201400594
View details for Web of Science ID 000351225700002
View details for PubMedID 25430948
View details for PubMedCentralID PMC4447497
- Self-Assembled Hydrogels Utilising Polymer-Nanoparticle Interactions Nature Communications 2015; 6: e6295
-
The control of cargo release from physically crosslinked hydrogels by crosslink dynamics
BIOMATERIALS
2014; 35 (37): 9897-9903
Abstract
Controlled release of drugs and other cargo from hydrogels has been an important target for the development of next generation therapies. Despite the increasingly strong focus in this area of research, very little of the published literature has sought to develop a fundamental understanding of the role of molecular parameters in determining the mechanism and rate of cargo release. Herein, a series of physically crosslinked hydrogels have been prepared utilizing host-guest binding interactions of cucurbit[8]uril that are identical in strength (plateau modulus), concentration and structure, yet exhibit varying network dynamics on account of the use of different guests for supramolecular crosslinking. The diffusion of molecular cargo through the hydrogel matrix and the release characteristics from these hydrogels were investigated. It was determined that the release processes of the hydrogels could be directly correlated with the dynamics of the physical interactions responsible for crosslinking and corresponding time-dependent mesh size. These observations highlight that network dynamics play an indispensable role in determining the release mechanism of therapeutic cargo from a hydrogel, identifying that fine-tuning of the release characteristics can be gained through rational design of the molecular processes responsible for crosslinking in the carrier hydrogels.
View details for DOI 10.1016/j.biomaterials.2014.08.001
View details for Web of Science ID 000343639700015
View details for PubMedID 25239043
-
GLUING GELS A nanoparticle solution
NATURE MATERIALS
2014; 13 (3): 231-232
View details for DOI 10.1038/nmat3893
View details for Web of Science ID 000331945200014
View details for PubMedID 24553651
- Activation Energies Control Macroscopic Properties of Supramolecular Crosslinked Materials Angewandte Chemie International Edition 2014; 53: 10038-10043
- Rapidly Healable, Temporally Stable and Stiff Hydrogels: Combining Conflicting Properties Using Highly Dynamic and Selective Three-Component Recognition with Reinforcing Cellulose Nanorods Advanced Functional Materials 2014; 24: 2706-2713
-
Dynamically crosslinked materials via recognition of amino acids by cucurbit[8]uril
JOURNAL OF MATERIALS CHEMISTRY B
2013; 1 (23): 2904-2910
View details for DOI 10.1039/c3tb20180e
View details for Web of Science ID 000319273100002
-
Triggered insulin release studies of triply responsive supramolecular micelles
POLYMER CHEMISTRY
2012; 3 (11): 3180-3188
View details for DOI 10.1039/c2py20380d
View details for Web of Science ID 000310421200021
- Ultra-High Water-Content Hydrogels from Renewable Resources Exhibiting Multi-Stimuli Responsiveness J. Am. Chem. Soc. 2012; 134: 11767-11773
-
Triply Triggered Doxorubicin Release From Supramolecular Nanocontainers
BIOMACROMOLECULES
2012; 13 (1): 84-91
Abstract
The synthesis of a supramolecular double hydrophilic block copolymer (DHBC) held together by cucurbit[8]uril (CB[8]) ternary complexation and its subsequent self-assembly into micelles is described. This system is responsive to multiple external triggers including temperature, pH and the addition of a competitive guest. The supramolecular block copolymer assembly consists of poly(N-isopropylacrylamide) (PNIPAAm) as a thermoresponsive block and poly(dimethylaminoethylmethacrylate) (PDMAEMA) as a pH-responsive block. Moreover, encapsulation and controlled drug release was demonstrated with this system using the chemotherapeutic drug doxorubicin (DOX). This triple stimuli-responsive DHBC micelle system represents an evolution over conventional double stimuli-responsive covalent diblock copolymer systems and displayed a significant reduction in the viability of HeLa cells upon triggered release of DOX from the supramolecular micellar nanocontainers.
View details for DOI 10.1021/bm201588m
View details for Web of Science ID 000298897300009
View details for PubMedID 22148638
-
Toward biodegradable nanogel star polymers via organocatalytic ROP
CHEMICAL COMMUNICATIONS
2012; 48 (49): 6163-6165
Abstract
Organocatalytic ring opening polymerization (OROP) is used to effect the rapid, scalable, room temperature formation of size-controlled, highly uniform, polyvalent, nanogel star polymer nanoparticles of biodegradable composition.
View details for DOI 10.1039/c2cc31406a
View details for Web of Science ID 000304363500028
View details for PubMedID 22590707
- High Molecular Weight Polyacrylamides by ATRP: Enabling Advancements in Water-based Applications J. Poly. Sci. Part A: Polym. Chem. 2012; 50: 181-186
-
Metastable single-chain polymer nanoparticles prepared by dynamic cross-linking with nor-seco-cucurbit[10]uril
CHEMICAL SCIENCE
2012; 3 (7): 2278-2281
View details for DOI 10.1039/c2sc20285a
View details for Web of Science ID 000304919200014
- Enhanced Stability and Activity of Temozolomide in Primary GBM Cells with Cucurbit[n]uril Chemical Communications 2012: 9843-9845
-
Supramolecular polymeric hydrogels
CHEMICAL SOCIETY REVIEWS
2012; 41 (18): 6195-6214
Abstract
The supramolecular crosslinking of polymer chains in water by specific, directional and dynamic non-covalent interactions has led to the development of novel supramolecular polymeric hydrogels. These aqueous polymeric networks constitute an interesting class of soft materials exhibiting attractive properties such as stimuli-responsiveness and self-healing arising from their dynamic behaviour and that are crucial for a wide variety of emerging applications. We present here a critical review summarising the formation of dynamic polymeric networks through specific non-covalent interactions, with a particular emphasis on those systems based on host-guest complex formation, as well as the characterisation of their physical characteristics. Aqueous supramolecular chemistry has unlocked a versatile toolbox for the design and fine-tuning of the material properties of these hydrogels (264 references).
View details for DOI 10.1039/c2cs35264h
View details for Web of Science ID 000307779600021
View details for PubMedID 22890548
-
Formation of Single-Chain Polymer Nanoparticles in Water through Host-Guest Interactions
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
2012; 51 (17): 4185-4189
View details for DOI 10.1002/anie.201108659
View details for Web of Science ID 000303001000037
View details for PubMedID 22422662
- Sustained Release of Proteins from a High-Water-Content Supramolecular Polymer Hydrogel Biomaterials 2012; 33: 4646-4652
-
Postpolymerization Modification of Hydroxyl-Functionalized Polymers with Isocyanates
MACROMOLECULES
2011; 44 (12): 4828-4835
View details for DOI 10.1021/ma2008018
View details for Web of Science ID 000291895700037
-
Supramolecular gold nanoparticle-polymer composites formed in water with cucurbit[8]uril
CHEMICAL COMMUNICATIONS
2011; 47 (1): 164-166
Abstract
A gold nanoparticle-polymer composite material has been prepared in water using cucurbit[8]uril as a supramolecular "handcuff" to hold together viologen-functionalised gold nanoparticles and a naphthol-functionalised acrylamide copolymer.
View details for DOI 10.1039/c0cc03250f
View details for Web of Science ID 000285068300008
View details for PubMedID 20842297
-
Supramolecular Cross-Linked Networks via Host-Guest Complexation with Cucurbit[8]uril
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
2010; 132 (40): 14251-14260
Abstract
The ability to finely tune the solution viscosity of an aqueous system is critical in many applications ranging from large-scale fluid-based industrial processes to free-standing hydrogels important in regenerative medicine, controlled drug delivery, and 'green' self-healing materials. Herein we demonstrate the use of the macrocyclic host molecule cucurbit[8]uril (CB[8]) to facilitate reversible cross-linking of multivalent copolymers with high binding constants (K(a) > 10(11)-10(12) M(-2)) leading to a supramolecular hydrogel. Multivalent copolymers were prepared by free radical polymerization techniques and contained either pendant methyl viologen (a good first guest for CB[8]) or naphthoxy derivatives (good second guests for CB[8]). A colorless solution of the two multivalent copolymers bearing first and second guests, respectively, can be transformed into a highly viscous, colored supramolecular hydrogel with the cross-link density being easily controlled through CB[8] addition. Moreover, the cross-links (1:1:1 supramolecular ternary complexes of CB[8]/viologen/naphthoxy) are dynamic and stimuli-responsive, and the material properties can be modulated by temperature or other external stimuli. Rheological characterization of the bulk material properties of these dynamically cross-linked networks provided insight into the kinetics of CB[8] ternary complexation responsible for elastically active cross-linking with a second guest dissociation rate constant (k(d)) of 1200 s(-1) for the ternary complex. These materials exhibited intermediate mechanical properties at 5 wt % in water (plateau modulus = 350-600 Pa and zero-shear viscosity = 5-55 Pa·s), which is complementary to existing supramolecular hydrogels. Additionally, these supramolecular hydrogels exhibited thermal reversibility and subsequent facile modulation of microstructure upon further addition of CB[8] and thermal treatment. The fundamental knowledge gained from the study of these dynamic materials will facilitate progress in the field of smart, self-healing materials, self-assembled hydrogels, and controlled solution viscosity.
View details for DOI 10.1021/ja106362w
View details for Web of Science ID 000282660100064
View details for PubMedID 20845973
-
Hierarchical Supermolecular Structures for Sustained Drug Release
SMALL
2009; 5 (13): 1504-1507
View details for DOI 10.1002/smll.200801756
View details for Web of Science ID 000267903200003
View details for PubMedID 19326354
-
Simple Approach to Stabilized Micelles Employing Miktoarm Terpolymers and Stereocomplexes with Application in Paclitaxel Delivery
BIOMACROMOLECULES
2009; 10 (6): 1460-1468
Abstract
A simple and versatile approach to miktoarm co- and terpolymers from carbonate functional oligomers is described. The key building block employed is a carboxylic acid functional cyclic carbonate, derived from 2,2-bis(methylol)propionic acid, that was readily coupled to a hydroxyl functional monomethylether poly(ethylene glycol) oligomer. Ring-opening of the cyclic carbonate using functional amines generates a carbamate linkage bearing a functional group capable of initiating either controlled radical or ring-opening polymerization, together with a primary hydroxyl group for ring-opening polymerization. Two tandem polymerization steps were possible which add the second two arms, thus generating the targeted ABC miktoarm terpolymer. The resulting amphiphilic miktoarm terpolymers containing poly(D- and L-lactide) formed polylactide stereocomplexes in the bulk. In aqueous solution, the stereocomplex mixture of Y-shaped miktoarm copolymers, poly(ethylene glycol)-poly(D-lactide)-poly(D-lactide) and poly(ethylene glycol)-poly(L-lactide)-poly(L-lactide), or the stereoblock miktoarm poly(ethylene glycol)-poly(D-lactide)-poly(L-lactide) form stabilized micelles with a significantly lower critical micelle concentration than those derived from conventional stereo regular linear or Y-shaped amphiphiles. This simple and versatile approach provides a useful synthetic route to complex macromolecular architectures that can assemble into stable micelles. These micelles provide high capacity for loading of the anticancer drug paclitaxel and possess narrow size distribution as well as unique structure, leading to sustained and near zero-ordered release of drug without significant initial burst.
View details for DOI 10.1021/bm900056g
View details for Web of Science ID 000266860700018
View details for PubMedID 19385659