Download polymerization

功能性高分子在基因/藥物傳遞上之應用
The Research Center of Textile and Fiber Materials
National Chung Hsing University
12/10/2014
陳致光
Department of Fiber and Composite Materials
Feng Chia University, Taichung
Short biography
主要學經歷
 89-91:台北科技大學化工學士
 91-93:台灣大學化工碩士
 94-98:工研院材化所副研究員
 98-103:紐約州立大學水牛城分校化工博士
 103-now:逢甲大學纖維與複合材料學系助理教授
研究專長
 生物可裂解基因載體之設計及合成
 以奈米中空微球作為藥物/基因共傳遞載體
 奈米微膠囊/纖維複合生醫織物之製備
 以靜電紡絲技術製備共聚合物之奈米纖維
Outline
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Recent developments in polymer chemistry
Polymeric materials for biomedical applications
Research work in biomedical polymers
Summary
Acknowledgement
What are polymers ?
 Polymers are macromolecules built up by linking together of
large number of much smaller molecules. The small molecules
that combine with each other to form polymer molecules are
termed as monomers, and the reactions by which they combine
are termed polymerization.
 Oligomers are molecules built up by the linking together of a few
monomers.
How to classify polymers ?
 There are several ways to classify polymers. One way to classify
polymers is based on how they are produced. Another way to
classify polymers is based on whether the repeating units for a
polymer are the same.
A controlled polymeric architecture by living polymerization
Features of living polymerization
 Controlled molecular weight
 Narrow size distribution PDI˂1.3
 With preserved end functionalities
Types of living polymerization techniques
 Living radical polymerization
 Living cationic/anionic polymerization
 Living ring-opening polymerization
Biodegradability can be rendered to the backbone
http://www.otsukac.co.jp/en/advanced/living/
Click reaction:A powerful tool for building up polymer architectures
Azide–alkyne cycloaddition reaction
 In 2001, Sharpless and coworkers
introduced the ‘‘click chemistry’’
concept that defines any reaction
which shows the following features
Thiol–ene reaction
 High yield
 High selectivity
 Low sensitivity to oxygen and water
 Simple separation procedures
 Mild reaction conditions
 High
amenability
to
starting
compounds
Thiol–maleimide addition, Thiol–isocyanate addition
K. Kempe, A. Krieg, C. R. Becer, U. S. Schubert, Chem Soc
Rev 2012, 41, 176.
Polymers: an ubiquitous material in everyday life
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Apparel
Electronic devices
Cosmetics
Automotive parts
Medicine (antibodies, protein, excipient, carrier)
Just about everywhere
Displays
Skin care products
fibers
Drug capsules
Polymers for biomedical applications
Drug delivery
Gene delivery
Nanofibers
Scaffolds
Antimicrobial materials
Biomedical
Polymers
Hydrogels
Surgical suture
Wound dressings
Cancer: a leading cause of mortality in Taiwan
General cancer treatments
Surgical removal of
tumor
Radiation therapy
Chemotherapy
 Chemotherapy: the use of anticancer drugs to initiate the
apoptosis mechanism by which cancer cells are killed, thereby
leading to the tumor shrinkage.
http://www.mohw.gov.tw/cht/DOS/Statistic.aspx?f_list_no=312&fod_list_no=1610
Limitations of chemotherapy
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Example: Paclitaxel (Taxol®)- treats numerous types of cancers
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Formulated with Cremophor® EL
Very high incidence & severity of toxicities
Limited therapeutic index
Drug exposure to tumor is low
Drug exposure to rest of body is high
Multi-drug resistance (MDR)
Chemotherapy
cannot
inhibit the tumor growth
due to MDR
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The MDR is caused by two major mechanisms. The first arises from the drug efflux
pump protein (P-gp) and the second results from self-anti-apoptosis protein (Bcl-2)
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Using gene therapy, the expression of these proteins can be effectively suppressed.
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A safe and efficient gene delivery vector is required.
M. Creixell, N. A. Peppas, Nano Today 2012, 7, 367.
Using nanocarriers to enhance therapeutic effects of anti-cancer
drugs
Anti-cancer drugs
Pros:
 An effective modality to
combat cancer-related
diseases
Paclitaxel
(PTXL)
Nano-sized (EPR effect)
Stimuli-responsive feature
PEGylation
Targeting ability
Imaging function
Nanotechnology
Polymeric
Nanomedicine
Cons:
Doxorubicin
(DOX)
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Polymer chemistry
Low water solubility
Low tumor permeability
Fast clearance
Adverse effects
Non-targeting
M. Skwarczynski, Y. Hayashi, Y. Kiso, J Med Chem 2006, 49, 7253.
drugs
nanocarriers
Rational design of polymeric nanoparticles for combating
cancer diseases
Improved circulation
time and stability
Increased encapsulation
efficiency
Various agents can be loaded into
nanoparticles
Enhanced cell uptake
In order to have the EPR effect
M. Elsabahy, K. L. Wooley, Chem Soc Rev 2012, 41, 2545.
Enhanced permeability and retention (EPR) effect
Blood
vessels
Blood
vessels
Angiogenesis and enhanced vascular permeability of tumor capillaries and impaired or missing
lymphatic clearance of macromolecules result in accumulation of macromolecules (polymers) in tumor
tissue.
Ulbrich K; Subr V., Adv Drug Delivery Rev 2004, 56, 1023.
Materials for gene delivery applications
Due to the repeated administration need in gene therapy, the safety and
biodegradability of vectors have to be taken into consideration for clinical applications.
V. Sokolova, M. Epple, Angew Chem Int Edit 2008, 47, 1382.
The applications of polymeric vectors in gene delivery
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Problems of gene delivery
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poor cell-uptake
low stability
rapid clearance
DNA or siRNA
fragile nature
Advantages of polymeric vectors
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low immune responses
biodegradability
versatility
low cost
protecting genes
Cationic polymers
Nanoplexes
Y. C. Chen, S. R. Bathula, J. Li, L. Huang, J Biol Chem 2010, 285, 22639.
Polymeric scaffolds for nanomedicines
Linear polymerdrug conjugate
Polymeric micelle
polymeric
scaffolds
Polymeric
nanosphere;
nanogel
Dendrimer
Hyperbrnched
polymer
Polymeric
nanocapsules (NCs)
The polymeric scaffolds should have:
 Significant water solubility or dispersibility
 Well-controlled nanoparticle sizes for preferred biodistribution
 Biodegradability to minimize side effects (MW < 45 kDa for complete clearance from circulation)
 Functionality to link with prodrug, targeting component, detection element, etc.
 Cationic groups to bind with genes for effective gene delivery.
Tong R; Cheng J. Polym Rev, 2007, 47 345.
Polymeric materials for drug/gene applications
Advantages of polymeric materials
• Versatile properties (biodegradability can be designed)
• Controllable size
• Feasibility of functionalization
Drug delivery
Gene delivery
• Protecting therapeutic genes
• Enhancing cell uptake
• Avoid rapid clearance
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Improved water solubility
Long circulation time
Enhanced accumulation in tumor
Targeting/imaging ability
Biodegradable cationic polylactides (CPLAs) and NCs for
gene/drug Delivery
Goal: To develop novel, safe biodegradable cationic scaffolds for gene and drug delivery.
Well-defined structures of CPLA/CPLA NC verified by 1H-NMR, FTIR, GPC, TEM and DLS
J. Zou, C. C. Hew, E. Themistou, Y. Li, C.-K. Chen, et al., Adv. Mater. 2011, 23, 4274.
C.-K. Chen, W.-C. Law, et al., Adv. Healthcare Mater. 2012, 1, 751.
C. H. Jones#, C.-K. Chen#, et al., Mol Pharmaceutics 2013, 10, 1138.
CPLA-based nanocomplexes as high efficient vectors for
siRNA/pDNA delivery to prostate cancer or macrophage cells
siRNA delivery
Safe biomaterials
TEM image of CPLA/siRNA
Cell uptake of nanoplexes
pDNA delivery
High transfection efficiency in macrophage cells
Transfection results
Degradable scaffolds TEM image of CPLA/pDNA
Strategies for enhancing in vivo applicability of resulting nanocomplexes
Stealthy coatings
against serum attack
1. Hydrophilic shielding layers
Approaches
Polyethylene glycol
PEG
Nanocomplexes
2. Zwitterionic polymers
 Resistance to nonspecific protein adsorption
 Improving colloidal stability
D. W. Pack, A. S. Hoffman, S. Pun, P. S. Stayton, Nat. Rev. Drug Discovery 2005, 4, 581.
J. Ladd, Z. Zhang, S. Chen, J. C. Hower, S. Jiang, Biomacromolecules 2008, 9, 1357.
PEGylated CPLAs for for enhanced gene delivery in
increasing levels of serum via nanocomplexes
Goal: To develop CPLA-based gene vectors to be relevant for clinical applications
C.-K. Chen, C.H. Jones, et al. Biomaterials 2013, 34, 9688.
Well-defined chemical structures of PEG-b-CPLAs
1H NMR results
GPC curves
PEG-b-CPLA/gene nanocomplexes
PDI = 1.05-1.06
DLS results
PEG-b-CPLA-20
TEM image
PEG-b-CPLA-50
Gene transfection study in four physiologically distinct cells
using PEG-b-CPLAs as vector
Advantages of PEGylation for CPLA-based vectors
Reduced hemolysis
Enhanced serum resistance
Synthesis of CPLA NCs and loading the NCs with therapeutic agents
Goal: To develop CPLA-based nanocapsules for overcoming MDR and enabling codelivery
C.-K. Chen, W.-C. Law et al., Nanoscale 2014, 6, 1567.
G. Lin, R. Hu, W.-C. Law, C.-K. Chen, et al., Small 2013, 9, 2757.
Overcoming MDR via encapsulation of NCs in MCF7/ADR cells
Dox-CPLA-NCs
free Dox
Enhanced intracellular concentration of Dox via NCs
50% increase in Dox-positive cells
Enhanced anti-proliferation effects
CPLA NCs as biodegradable carriers for drug/gene codelivery
Cell uptake of Dox-CPLA NCs
Antiproliferation of PC3 cells
Cell uptake of siRNA-CPLA NCs
Transfection results
Codelivery of siRNA/Dox via NCs
Synergetic antitumor effects via codelivery
Synthesis of pH-responsive CSNCs via interfacial
miniemulsion crosslinking for drug delivery
Goal: To develop pH-responsive chitosan nanocapsules
(a) Preparation of Dox-loaded chitosan nanocapsules (Dox-CSNCs) via miniemulsion
interfacial crosslinking, (b) The acid-labile cross-linkage of CSNCs, (c) The appearance of
Dox-loaded CSNC-3 solution.
C.-K. Chen, Q. Wang et al., Langmuir 2014, 30, 4111.
Well-defined chitosan nanocapsules with pH-responsive feature
Tunable size feature
pH-dependant drug release
Capsular structure
Non-toxic and higher antitumor efficacy
Summary
Nanocomplexs
for gene delivery
PEGylated Nanocomplexs
with high serum resistance
CPLAs
CPLA NCs
H+
pH-responsive
chitosan nanocapules
for overcoming MDR and enabling gene/drug delivery
Acknowledgement
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Ph.D. advisor
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Current group members
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林威任、黃思傑
Collaborator
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Dr. Chong Cheng
Prof. Blaine Pfeifer, Prof. Paras N. Prasad at UB
國衛院羅履維老師
南洋理工大學Prof. Ken-Tye Yang
Funding supports
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科技部(MOST 103-2218-E-035 -010)
逢甲大學(startup funding)
Thank you for your attention