Special Issue "Polymer-Based Systems for Controlled Release and Targeting of Drugs"

A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: 31 July 2019

Special Issue Editors

Guest Editor
Prof. Dr. Gaetano Giammona

Laboratory of Biocompatible Polymers, Department of “Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche” (STEBICEF), University of Palermo, Via Archirafi, 32 90123 Palermo, Italy
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Interests: synthesis and physicochemical characterization of biocompatible polymers; innovative drug delivery systems; drug and gene delivery; hydrogels; three-dimensional scaffolds; tissue engineering; regenerative medicine; targeted release; lipid-based drug delivery systems; theranostic systems
Guest Editor
Dr. Emanuela Fabiola Craparo

Laboratory of Biocompatible Polymers, Department of “Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche” (STEBICEF), University of Palermo, Via Archirafi, 32 90123 Palermo, Italy
Website | E-Mail
Interests: functionalization and purification of biopolymers; controlled drug release; active targeting; micro- and nanoparticles; polymeric micelles; lipid-based nanostructured systems; polycations; gene therapy; imaging

Special Issue Information

Dear Colleagues,

The need to find new advanced approaches of care for the most serious pathologies that affect humans, from the possibility of dissolving biologically-active substances (conventional organic drugs, peptides, proteins, such as antibodies, nucleic acid-based drugs (NABDs), such as siRNA, miRNA) in body fluids, to targeted therapies and personalized ones, continues, hand-in-hand, with research on new performing materials to better achieve these goals through the realization of appropriate vectors for the delivery of these bioactive molecules.

Polymeric materials can be designed and manufactured for obtaining delivery systems with appropriate characteristics in terms of drug release and performance. To be used for human applications, a polymer must be primarily biocompatible and non-toxic, and also functionalizable to give appropriate structural and functional characteristics, such as to make it easily workable,

This Special Issue aims to attract researchers who are currently working on the design and production of polymeric materials, as well as work on the search for strategies to modify existing ones for making innovative systems for drug delivery and/or regenerative medicine. In particular, we expect to receive original papers or reviews on polymeric systems, ranging from nano- to macro-structures, for drug and/or cell delivery.

Prof. Gaetano Giammona
Prof. Emanuela Fabiola Craparo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Biocompatible polymers
  • Drug delivery systems
  • Gene therapy
  • Tissue engineering
  • Targeted drug release
  • Personalized medicine
  • Nanoparticles
  • Microparticles
  • Polyplexes

Published Papers (10 papers)

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Research

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Open AccessArticle
Combining Inulin Multifunctional Polycation and Magnetic Nanoparticles: Redox-Responsive siRNA-Loaded Systems for Magnetofection
Polymers 2019, 11(5), 889; https://doi.org/10.3390/polym11050889
Received: 12 April 2019 / Revised: 3 May 2019 / Accepted: 9 May 2019 / Published: 15 May 2019
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Abstract
Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are recognized as one of the most promising agents for theranostic applications. Among methods designed for siRNA delivery, magnetofection, that is, nucleic acid cell uptake under the influence of a magnetic field acting on magnetic nucleic acid vectors, [...] Read more.
Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are recognized as one of the most promising agents for theranostic applications. Among methods designed for siRNA delivery, magnetofection, that is, nucleic acid cell uptake under the influence of a magnetic field acting on magnetic nucleic acid vectors, is emerging as a unique approach to combining advantages such as strong improvement of the kinetics of the delivery process and the possibility of localizing nucleic acid delivery to an area where the magnetic field is applied. This paper reports on the preparation of siRNA loaded magnetoplexes—named [email protected]@SPIONs/siRNA—by controlled crosslinking, in the presence of SPIONs, of the polycation INU-C-DETA, synthesized starting from the polysaccharide inulin by grafting diethylenetriamine and cystamine molecules. The obtained [email protected]@SPIONs/siRNA have suitable chemical-physical characteristics to be employed for iv administration and are also able to release siRNA in a redox-triggered manner thanks to intracellular glutathione (GSH) mediated reduction of disulphide bridges formed during the crosslinking process. Moreover, [email protected]@SPIONs/siRNA are able to produce magnetic targeting in vitro on breast cancer cells, without appreciable cyto- and hemo-toxic effects, in a wide range of concentrations. Finally, protein binding to nanoparticles revealed that obtained systems are potentially longer circulating and applicable as a smart multifunctional agents for cancer therapy. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle
Characterization and Optimization of PLA Stereocomplexed Hydrogels for Local Gene Delivery Systems
Polymers 2019, 11(5), 796; https://doi.org/10.3390/polym11050796
Received: 9 April 2019 / Revised: 29 April 2019 / Accepted: 29 April 2019 / Published: 3 May 2019
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Abstract
Localized gene delivery still remains as a challenging therapeutic method due to the multiple hurdles to overcome. One of the significant factors is a development of a matrix to carry and safely deliver genes at the local site in a controlled manner and [...] Read more.
Localized gene delivery still remains as a challenging therapeutic method due to the multiple hurdles to overcome. One of the significant factors is a development of a matrix to carry and safely deliver genes at the local site in a controlled manner and then exit and disintegrate harmlessly. This report describes the structural and mechanistic studies on the in-situ forming hydrogels composed of the PEI/DNA multi-layered micelles to apply for gene therapy. The stereocomplexation-driven hydrogel systems from the DNA-loaded and DNA-free PLA-PEG-PLA triblock copolymer micelles that include enantiomeric polylactide blocks exhibited a sol-to-gel transitions between room and body temperatures. These hydrogels have well-described structure and compositions, and improved mechanical properties. Furthermore, the investigation of their degradation profiles and chemical analysis indicated the faster acidic degradation and stepwise degradation process of these micelle–hydrogel systems. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle
Microfluidic Based Fabrication and Characterization of Highly Porous Polymeric Microspheres
Polymers 2019, 11(3), 419; https://doi.org/10.3390/polym11030419
Received: 31 January 2019 / Revised: 23 February 2019 / Accepted: 28 February 2019 / Published: 5 March 2019
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Abstract
Polymeric porous particles are currently used for various applications in biotechnology, tissue engineering and pharmaceutical science, e.g., floating drug delivery systems and inhaled formulations. Particle shape and size depend on variable parameters; among them, polymer type and concentration, stirring speed, pH and type [...] Read more.
Polymeric porous particles are currently used for various applications in biotechnology, tissue engineering and pharmaceutical science, e.g., floating drug delivery systems and inhaled formulations. Particle shape and size depend on variable parameters; among them, polymer type and concentration, stirring speed, pH and type of solvent. In this study, porous poly(lactic-co-glycolic) acid (PLGA) and poly(d,l-lactide) (PLA) microspheres (MPs), with varying sizes and morphologies, were synthesized and optimized using both batch formulation and a flow-focusing microfluidic device. A well-established method of preparation utilizing solvent evaporation and the double emulsion technique was performed. Similar to other batch encapsulation methods, this technique is time and reagent consuming and consists of several steps. Hence, although porous structures provide tremendous opportunity in the design of new applications for tissue engineering and as improved controlled-release carriers, the synthesis of these particles with predefined properties remains challenging. We demonstrated the fabrication of porous MPs using a simple microfluidic device, compared to batch synthesis fabrication; and the effect of solvent, polymer concentration and type, post-hydrolysis treatment, on porosity degree. Moreover, a kinetic release study of fluorescent molecule was conducted for non-porous in comparison to porous particles. An overview of future prospects and the potential of these porous beads in this scientific area are discussed. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle
Temperature Responsive Nanoparticles Based on PEGylated Polyaspartamide Derivatives for Drug Delivery
Polymers 2019, 11(2), 316; https://doi.org/10.3390/polym11020316
Received: 19 January 2019 / Revised: 9 February 2019 / Accepted: 11 February 2019 / Published: 13 February 2019
PDF Full-text (1987 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The temperature responsive PEGylated polyaspartamide derivative, denoted as mPEG-PAAHP, was synthesized by the click reaction. FTIR and 1H NMR were adopted to characterize and confirm the chemical structures of the obtained mPEG-PAAHPs. The temperature responsive behavior investigated by transmittance and dynamic light [...] Read more.
The temperature responsive PEGylated polyaspartamide derivative, denoted as mPEG-PAAHP, was synthesized by the click reaction. FTIR and 1H NMR were adopted to characterize and confirm the chemical structures of the obtained mPEG-PAAHPs. The temperature responsive behavior investigated by transmittance and dynamic light scattering showed that some of the obtained mPEG-PAAHPs exhibited obvious temperature responsiveness and could be used to prepare nanoparticles by quickly heating. Drug paclitaxel can be encapsulated into mPEG-PAAHP based nanoparticles with a high encapsulation efficiency up to 99% (corresponding to a drug loading content of around 9.9%). Dynamic light scattering results showed that the PTX-loaded nanoparticles had a mean size around 80 nm (PDI<0.2) and good stability in PBS with 150 mM ionic strength. In vitro cytotoxicity results showed that mPEG-PAAHP did not show any toxicity to HeLa cells, but the PTX-loaded nanoparticles based on mPEG-PAAHP exhibited obvious anti-cancer activity. Thus, the temperature responsive PEGylated polyaspartamide derivative mPEG-PAAHP may be a promising drug delivery system. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle
Facile Preparation of Reduction-Responsive Micelles Based on Biodegradable Amphiphilic Polyurethane with Disulfide Bonds in the Backbone
Polymers 2019, 11(2), 262; https://doi.org/10.3390/polym11020262
Received: 3 January 2019 / Revised: 30 January 2019 / Accepted: 30 January 2019 / Published: 4 February 2019
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Abstract
In this paper, we synthesized a biodegradable amphiphilic polymer of polyurethane-polyethylene glycol with disulfide bonds in the main chain (PEG-PU(SS)-PEG). DLS and SEM showed that the polymer could self-assemble into micelles in aqueous solution and could be used to load the hydrophobic anticancer [...] Read more.
In this paper, we synthesized a biodegradable amphiphilic polymer of polyurethane-polyethylene glycol with disulfide bonds in the main chain (PEG-PU(SS)-PEG). DLS and SEM showed that the polymer could self-assemble into micelles in aqueous solution and could be used to load the hydrophobic anticancer drug DOX. Intriguingly, drug release in vitro indicated that DOX-loaded PEG-PU(SS)-PEG micelles had good stability under the extracellular physiological environment, but the disulfide bonds broke rapidly and DOX was released quickly under the intracellular reducing conditions. CCK-8 assays showed that DOX-loaded PEG-PU(SS)-PEG micelles had a high in vitro antitumor activity in C6 cells, whereas blank PEG-PU(SS)-PEG micelles were nontoxic to C6 cells. It was also found that there was strong and persistent accumulation of DOX-loaded PEG-PU(SS)-PEG as compared with PEG-PU-PEG both by the cell internalization tests and the flow cytometry measurements. Hence, PEG-PU(SS)-PEG micelles will have a potential use for clinical treatment of cancer in the future. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle
Starch-Based Pickering Emulsions as Platforms for Topical Antibiotic Delivery: In Vitro and In Vivo Studies
Polymers 2019, 11(1), 108; https://doi.org/10.3390/polym11010108
Received: 7 December 2018 / Revised: 27 December 2018 / Accepted: 7 January 2019 / Published: 10 January 2019
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Abstract
The present study investigated a new approach to treat superficial skin infections by topical application of minocycline hydrochloride (MH) formulated in a novel starch-based Pickering emulsion (ASt-emulsions). The emulsions were fully characterized in terms of efficacy, as well as in vitro release and [...] Read more.
The present study investigated a new approach to treat superficial skin infections by topical application of minocycline hydrochloride (MH) formulated in a novel starch-based Pickering emulsion (ASt-emulsions). The emulsions were fully characterized in terms of efficacy, as well as in vitro release and permeation studies. The emulsions provided a prolonged MH release, always above its minimum inhibitory concentration against Staphylococcus aureus, although the drug did not permeate through the entire skin layer. The in vitro antibacterial activity of MHASt-emulsions against S. aureus was confirmed and their therapeutic efficacy was assessed using an in vitro skin-adapted agar diffusion test. In vivo antibacterial activity, evaluated using the tape-stripping infection model in mice, showed the topical administration of MH was effective against superficial infections caused by S. aureus. This study supports the potential of ASt-emulsions as promising platforms for topical antibiotic delivery, contributing to a new perspective on the treatment of superficial bacterial infections. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle
Solid-Phase Synthesis of Cellulose Acetate Butyrate as Microsphere Wall Materials for Sustained Release of Emamectin Benzoate
Polymers 2018, 10(12), 1381; https://doi.org/10.3390/polym10121381
Received: 13 November 2018 / Revised: 5 December 2018 / Accepted: 10 December 2018 / Published: 13 December 2018
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Abstract
Emamectin benzoate (EB), a widely used pesticide, is prone to decomposition by ultraviolet light and suffers from the corresponding loss of efficacy. The timed release of EB based on microspheres is one of the effective methods to solve this issue. As a non-toxic [...] Read more.
Emamectin benzoate (EB), a widely used pesticide, is prone to decomposition by ultraviolet light and suffers from the corresponding loss of efficacy. The timed release of EB based on microspheres is one of the effective methods to solve this issue. As a non-toxic cellulose ester, cellulose acetate butyrate (CAB) is regarded as one of the best wall-forming materials for microcapsules with a good controlled release performance. Herein, two methods—mechanical activation (MA) technology and a conventional liquid phase (LP) method—were employed to synthesize different CABs, namely CAB-MA and CAB-LP, respectively. The molecular structure, rheological property, and thermal stability of these CABs were investigated. The two CABs were used to prepare microspheres for the loading and release of EB via an o/w (oil-in-water) solvent evaporation method. Moreover, the performances such as drug loading, drug entrapment, and anti-photolysis of the drug for these microspheres were studied. The results showed that both CABs were available as wall materials for loading and releasing EB. Compared with CAB-LP, CAB-MA presented a lower molecular weight and a narrower molecular weight distribution. Moreover, the MA method endowed the CAB with more ester substituent groups and less crystalline structure in comparison to the LP method, which had benefits including pelletizing and drug loading. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle
Design, Synthesis, and Characterization of Schiff Base Bond-Linked pH-Responsive Doxorubicin Prodrug Based on Functionalized mPEG-PCL for Targeted Cancer Therapy
Polymers 2018, 10(10), 1127; https://doi.org/10.3390/polym10101127
Received: 29 September 2018 / Revised: 8 October 2018 / Accepted: 10 October 2018 / Published: 11 October 2018
Cited by 1 | PDF Full-text (3102 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The side effects of doxorubicin (DOX) extremely limit its application in the treatment of malignant tumors. Nano-sized polymeric drugs based on the acidic microenvironment of tissular- or intra- tumor have attracted ample attention because of their potential in reducing side effects. In this [...] Read more.
The side effects of doxorubicin (DOX) extremely limit its application in the treatment of malignant tumors. Nano-sized polymeric drugs based on the acidic microenvironment of tissular- or intra- tumor have attracted ample attention because of their potential in reducing side effects. In this research, an amphiphilic diblock copolymer based on poly (ethylene glycol) (PEG) and functionalized polycaprolactone (PCL) was synthesized and utilized as the drug carrier. DOX was chemically conjugated with the polymer via acid-cleavable imine bonds to obtain a novel pH-sensitive DOX prodrug (mPEG-PCL-Imi-DOX). mPEG-PCL-Imi-DOX (24.2 wt % DOX content) formed micelles with an average diameter of 125 nm through a simple solvent evaporation method. The in vitro release profile demonstrated that DOX release of the prodrug micelles was pH-responsive and able to be accelerated with the decrease of pH. In vitro cytotoxicity assay tests revealed that the pH-sensitive DOX prodrug micelles exhibited relatively lower toxicity and similar antitumor efficacy towards MCF-7 cells compared with free DOX. Hence, the DOX prodrug micelles with imine bonds can offer a carrier with great potential for chemo-therapeutics. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Open AccessArticle
Preparation and Evaluation of Metronidazole-Loaded Pectin Films for Potentially Targeting a Microbial Infection Associated with Periodontal Disease
Polymers 2018, 10(9), 1021; https://doi.org/10.3390/polym10091021
Received: 20 August 2018 / Accepted: 4 September 2018 / Published: 13 September 2018
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Abstract
The objective of this study was to develop the metronidazole loaded high and low methoxyl pectin films (HM-G-MZ and LM-G-MZ) for the treatment of periodontal disease. The films were prepared by pectin 3% w/v, glycerin 40% w/v, [...] Read more.
The objective of this study was to develop the metronidazole loaded high and low methoxyl pectin films (HM-G-MZ and LM-G-MZ) for the treatment of periodontal disease. The films were prepared by pectin 3% w/v, glycerin 40% w/v, and metronidazole 5% w/v. The developed films were characterized by scanning electron microscope and evaluated for thickness, weight variation, and elasticity. The developed films showing optimal mechanical properties were selected to evaluate radial swelling properties, in vitro release of metronidazole and the antimicrobial activity against Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans by the disc diffusion method. The results demonstrated that LM-MZ and HM-G-MZ films were colorless and yellowish color, respectively, with the film thickness around 0.36–0.38 mm. Furthermore, both films exhibited good elasticity with low puncture strength (1.63 ± 0.37 and 0.84 ± 0.03 N/mm2, respectively) and also showed slight increase in radial swelling, so that they could be easily inserted and fitted into the periodontal pocket during a clinical use. However, HM-G-MZ showed a decrease in radial swelling after 1 h due to the film erosion. The in vitro release study of LM-G-MZ showed a burst release that was initially followed by a slow release rate profile, capable to maintain the therapeutic level in periodontal pocket for seven days, whereas HM-G-MZ showed an immediate release profile. The cumulative percentage of metronidazole release from HM-G-MZ was less than LM-G-MZ during the first 5 min as metronidazole was in a crystalline form inside HM-G-MZ film. For antimicrobial activity test, both films showed the inhibitory effect against P. gingivalis and A. actinomycetemcomitans, and there was no difference in the inhibition zone between LM-G-MZ and HM-G-MZ. The present study showed, for the first time, that low methoxyl pectin film containing glycerin and metronidazole could be potentially considered as a promising clinical tool for the drug delivery via intra-periodontal pocket to target an oral disease that is associated with polymicrobial infection. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Review

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Open AccessReview
Implantable Polymeric Drug Delivery Devices: Classification, Manufacture, Materials, and Clinical Applications
Polymers 2018, 10(12), 1379; https://doi.org/10.3390/polym10121379
Received: 8 November 2018 / Accepted: 10 December 2018 / Published: 12 December 2018
Cited by 3 | PDF Full-text (2809 KB) | HTML Full-text | XML Full-text
Abstract
The oral route is a popular and convenient means of drug delivery. However, despite its advantages, it also has challenges. Many drugs are not suitable for oral delivery due to: first pass metabolism; less than ideal properties; and side-effects of treatment. Additionally, oral [...] Read more.
The oral route is a popular and convenient means of drug delivery. However, despite its advantages, it also has challenges. Many drugs are not suitable for oral delivery due to: first pass metabolism; less than ideal properties; and side-effects of treatment. Additionally, oral delivery relies heavily on patient compliance. Implantable drug delivery devices are an alternative system that can achieve effective delivery with lower drug concentrations, and as a result, minimise side-effects whilst increasing patient compliance. This article gives an overview of classification of these drug delivery devices; the mechanism of drug release; the materials used for manufacture; the various methods of manufacture; and examples of clinical applications of implantable drug delivery devices. Full article
(This article belongs to the Special Issue Polymer-Based Systems for Controlled Release and Targeting of Drugs)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Dr. Wenwen Deng

Tentative title: Enhanced oral bioavailability, liver targeting and hepatoprotective efficiency of syringic acid via TPGS/F127/F68 mixed polymeric micelles

Dr. Sung Eun Kim

Tentative title: Local delivery of dexamethasone via porous microspheres suppresses Achilles tendinitis

Dr. Reza Fassihi

Tentative title: Advances in Controlled Release Delivery Systems for GI Targeting

Dr. Viktor Korzhikov-Vlakh

Tentative title: To be determined

Dr. Yu-Wen Ting

Tentative title: To be determined

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