{"id":{"repo_id":"auckland-ms","oai_identifier":"oai:researchspace.auckland.ac.nz:2292/33210"},"canonical_url":"https://search.dev.ndltd.org/etd/auckland-ms/oai:researchspace.auckland.ac.nz:2292/33210","repository":{"repo_id":"auckland-ms","name":"University of Auckland","base_url":"https://researchspace.auckland.ac.nz/server/oai/request"},"display":{"title":"Conducting Polymer Implant for On-demand Ocular Drug Delivery","abstract":"Introduction: Implants have become an attractive treatment option for chronic posterior eye conditions. However, a patient’s disease state and any concurrent side-effects may require a dose adjustment which is not possible with currently marketed implants. Stimuli-responsive implants present an opportunity to tailor the release of the active. They may be composed of conducting polymers (CP) such as poly(3,4-ethylenedioxythiophene) (PEDOT), a robust CP with good biocompatibility and reproducible electroactivity. This thesis investigated the fabrication of a PEDOT-based system suitable for implantation to provide stimuli-responsive ocular drug delivery. Methods: PEDOT films (non-porous and porous) were fabricated via vapour phase polymerisation (VPP) and characterised for their surface morphology, electrochemical behaviour and biocompatibility. Dexamethasone phosphate (dexP) was loaded after polymerisation as a dopant via active and passive ion-exchange. DexP release was determined in the absence and presence of an electrical stimulus. Dexamethasone base (dex) was also physically entrapped into the pores of porous PEDOT and a sealing layer was polymerized on top. PEDOT-coated cellulose membranes, replicating the PEDOT sealing layer, were also fabricated and characterised for their drug permeability using Franz-cells. Finally, a prototype implant for in-vitro evaluation was fabricated by 3D printing the casing and placing drug loaded VPP PEDOT films inside. Results and Discussion: Porous PEDOT prepared by VPP exhibited a highly porous morphology and a three-fold higher electrochemically active surface area (as determined by cyclic voltammetry) compared to non-porous PEDOT prepared by VPP. Release medium extracts from non-porous and porous PEDOT films displayed no significant cytotoxicity. The amount of dexP loading achieved via active ion-exchange was almost three-fold higher compared to passive ion-exchange. The effect of redox state over dexP release was determined where a pulse stimulus released maximum amounts of drug. A faster rate of dexP release was observed for porous compared to non-porous films. Dex was physically entrapped into the pores to increase drug loading; however, it leaked through the PEDOT sealing layer within 1 h. PEDOT-coated cellulose membranes confirmed the high permeability of these sealing layers. Therefore, the assembled prototype implant contained only dexP loaded films and exhibited a burst in drug release during in-vitro stimulation aligning well with previous dexP release where a similar burst in drug release was observed upon the application of in-vitro stimulus. Conclusion: A PEDOT-based system suitable for implantation was fabricated exhibiting a stimuli-responsive burst in drug release. However, drug loading and retention need to be further improved such as by physical entrapment and effective sealing to achieve long-term on-demand drug delivery.","abstract_html":"Introduction: Implants have become an attractive treatment option for chronic posterior eye conditions. However, a patient’s disease state and any concurrent side-effects may require a dose adjustment which is not possible with currently marketed implants. Stimuli-responsive implants present an opportunity to tailor the release of the active. They may be composed of conducting polymers (CP) such as poly(3,4-ethylenedioxythiophene) (PEDOT), a robust CP with good biocompatibility and reproducible electroactivity. This thesis investigated the fabrication of a PEDOT-based system suitable for implantation to provide stimuli-responsive ocular drug delivery. Methods: PEDOT films (non-porous and porous) were fabricated via vapour phase polymerisation (VPP) and characterised for their surface morphology, electrochemical behaviour and biocompatibility. Dexamethasone phosphate (dexP) was loaded after polymerisation as a dopant via active and passive ion-exchange. DexP release was determined in the absence and presence of an electrical stimulus. Dexamethasone base (dex) was also physically entrapped into the pores of porous PEDOT and a sealing layer was polymerized on top. PEDOT-coated cellulose membranes, replicating the PEDOT sealing layer, were also fabricated and characterised for their drug permeability using Franz-cells. Finally, a prototype implant for in-vitro evaluation was fabricated by 3D printing the casing and placing drug loaded VPP PEDOT films inside. Results and Discussion: Porous PEDOT prepared by VPP exhibited a highly porous morphology and a three-fold higher electrochemically active surface area (as determined by cyclic voltammetry) compared to non-porous PEDOT prepared by VPP. Release medium extracts from non-porous and porous PEDOT films displayed no significant cytotoxicity. The amount of dexP loading achieved via active ion-exchange was almost three-fold higher compared to passive ion-exchange. The effect of redox state over dexP release was determined where a pulse stimulus released maximum amounts of drug. A faster rate of dexP release was observed for porous compared to non-porous films. Dex was physically entrapped into the pores to increase drug loading; however, it leaked through the PEDOT sealing layer within 1 h. PEDOT-coated cellulose membranes confirmed the high permeability of these sealing layers. Therefore, the assembled prototype implant contained only dexP loaded films and exhibited a burst in drug release during in-vitro stimulation aligning well with previous dexP release where a similar burst in drug release was observed upon the application of in-vitro stimulus. Conclusion: A PEDOT-based system suitable for implantation was fabricated exhibiting a stimuli-responsive burst in drug release. However, drug loading and retention need to be further improved such as by physical entrapment and effective sealing to achieve long-term on-demand drug delivery.","abstract_has_math":false,"creators":["Yasin, Muhammad Naveed"],"institution":"ResearchSpace@Auckland","degree_name":"PhD","degree_level":"Doctoral","degree_discipline":"Ophthalmology","degree_department":null,"school":null,"contributors":[],"advisors":["Rupenthal, I","Svirskis, D","Seyfoddin, A"],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016","date_published":"2016","updated_at":"2026-07-24T01:07:07Z","subjects":[],"languages":[],"rights":["Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher."],"rights_urls":["https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm"],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2292/33210","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Rupenthal, I","Svirskis, D","Seyfoddin, A"]},{"key":"dc:creator","label":"Author","values":["Yasin, Muhammad Naveed"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2017-05-31T22:06:27Z"]},{"key":"dc:date.issued","label":"Date","values":["2016"]},{"key":"dc:publisher","label":"Institution","values":["ResearchSpace@Auckland"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["UoA99265046007402091"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Ophthalmology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["PhD"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["The University of Auckland"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher."]},{"key":"dc:rights.uri","label":"Rights URI","values":["https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/2292/33210"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Introduction: Implants have become an attractive treatment option for chronic posterior eye conditions. However, a patient’s disease state and any concurrent side-effects may require a dose adjustment which is not possible with currently marketed implants. Stimuli-responsive implants present an opportunity to tailor the release of the active. They may be composed of conducting polymers (CP) such as poly(3,4-ethylenedioxythiophene) (PEDOT), a robust CP with good biocompatibility and reproducible electroactivity. This thesis investigated the fabrication of a PEDOT-based system suitable for implantation to provide stimuli-responsive ocular drug delivery. Methods: PEDOT films (non-porous and porous) were fabricated via vapour phase polymerisation (VPP) and characterised for their surface morphology, electrochemical behaviour and biocompatibility. Dexamethasone phosphate (dexP) was loaded after polymerisation as a dopant via active and passive ion-exchange. DexP release was determined in the absence and presence of an electrical stimulus. Dexamethasone base (dex) was also physically entrapped into the pores of porous PEDOT and a sealing layer was polymerized on top. PEDOT-coated cellulose membranes, replicating the PEDOT sealing layer, were also fabricated and characterised for their drug permeability using Franz-cells. Finally, a prototype implant for in-vitro evaluation was fabricated by 3D printing the casing and placing drug loaded VPP PEDOT films inside. Results and Discussion: Porous PEDOT prepared by VPP exhibited a highly porous morphology and a three-fold higher electrochemically active surface area (as determined by cyclic voltammetry) compared to non-porous PEDOT prepared by VPP. Release medium extracts from non-porous and porous PEDOT films displayed no significant cytotoxicity. The amount of dexP loading achieved via active ion-exchange was almost three-fold higher compared to passive ion-exchange. The effect of redox state over dexP release was determined where a pulse stimulus released maximum amounts of drug. A faster rate of dexP release was observed for porous compared to non-porous films. Dex was physically entrapped into the pores to increase drug loading; however, it leaked through the PEDOT sealing layer within 1 h. PEDOT-coated cellulose membranes confirmed the high permeability of these sealing layers. Therefore, the assembled prototype implant contained only dexP loaded films and exhibited a burst in drug release during in-vitro stimulation aligning well with previous dexP release where a similar burst in drug release was observed upon the application of in-vitro stimulus. Conclusion: A PEDOT-based system suitable for implantation was fabricated exhibiting a stimuli-responsive burst in drug release. However, drug loading and retention need to be further improved such as by physical entrapment and effective sealing to achieve long-term on-demand drug delivery."]},{"key":"dc:title","label":"Title","values":["Conducting Polymer Implant for On-demand Ocular Drug Delivery"]}]}],"canonical_facts":{"dc:contributor.advisor":["Rupenthal, I","Svirskis, D","Seyfoddin, A"],"dc:creator":["Yasin, Muhammad Naveed"],"dc:date.accessioned":["2017-05-31T22:06:27Z"],"dc:date.issued":["2016"],"dc:description.abstract":["Introduction: Implants have become an attractive treatment option for chronic posterior eye conditions. However, a patient’s disease state and any concurrent side-effects may require a dose adjustment which is not possible with currently marketed implants. Stimuli-responsive implants present an opportunity to tailor the release of the active. They may be composed of conducting polymers (CP) such as poly(3,4-ethylenedioxythiophene) (PEDOT), a robust CP with good biocompatibility and reproducible electroactivity. This thesis investigated the fabrication of a PEDOT-based system suitable for implantation to provide stimuli-responsive ocular drug delivery. Methods: PEDOT films (non-porous and porous) were fabricated via vapour phase polymerisation (VPP) and characterised for their surface morphology, electrochemical behaviour and biocompatibility. Dexamethasone phosphate (dexP) was loaded after polymerisation as a dopant via active and passive ion-exchange. DexP release was determined in the absence and presence of an electrical stimulus. Dexamethasone base (dex) was also physically entrapped into the pores of porous PEDOT and a sealing layer was polymerized on top. PEDOT-coated cellulose membranes, replicating the PEDOT sealing layer, were also fabricated and characterised for their drug permeability using Franz-cells. Finally, a prototype implant for in-vitro evaluation was fabricated by 3D printing the casing and placing drug loaded VPP PEDOT films inside. Results and Discussion: Porous PEDOT prepared by VPP exhibited a highly porous morphology and a three-fold higher electrochemically active surface area (as determined by cyclic voltammetry) compared to non-porous PEDOT prepared by VPP. Release medium extracts from non-porous and porous PEDOT films displayed no significant cytotoxicity. The amount of dexP loading achieved via active ion-exchange was almost three-fold higher compared to passive ion-exchange. The effect of redox state over dexP release was determined where a pulse stimulus released maximum amounts of drug. A faster rate of dexP release was observed for porous compared to non-porous films. Dex was physically entrapped into the pores to increase drug loading; however, it leaked through the PEDOT sealing layer within 1 h. PEDOT-coated cellulose membranes confirmed the high permeability of these sealing layers. Therefore, the assembled prototype implant contained only dexP loaded films and exhibited a burst in drug release during in-vitro stimulation aligning well with previous dexP release where a similar burst in drug release was observed upon the application of in-vitro stimulus. Conclusion: A PEDOT-based system suitable for implantation was fabricated exhibiting a stimuli-responsive burst in drug release. However, drug loading and retention need to be further improved such as by physical entrapment and effective sealing to achieve long-term on-demand drug delivery."],"dc:identifier.uri":["https://hdl.handle.net/2292/33210"],"dc:publisher":["ResearchSpace@Auckland"],"dc:relation.isreferencedby":["UoA99265046007402091"],"dc:rights":["Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher."],"dc:rights.uri":["https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm"],"dc:title":["Conducting Polymer Implant for On-demand Ocular Drug Delivery"],"dc:type":["Thesis"],"thesis:degree_discipline":["Ophthalmology"],"thesis:degree_level":["Doctoral"],"thesis:degree_name":["PhD"],"thesis:institution_name":["The University of Auckland"]},"updated_at":"2026-07-24T01:07:07Z"}