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The effect of curing conditions on compression strength and porosity of metakaolin-based geopolymers
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Material in Medicine)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Material in Medicine)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Materials in medicine)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
2013 (English)In: Developments in Strategic Materials and Computational Design IV, John Wiley & Sons, 2013Conference paper, Published paper (Refereed)
Abstract [en]

Geopolymers have been suggested to use as construction, waste treatment and fire proof materials and even drug delivery material due to its excellent mechanical strength, chemical stability and flame resistance. The aim of this study was to investigate the influence of temperature, time and humidity during curing on mechanical strength and porosity of geopolymers.

The geopolymer precursor paste was obtained by mixing metakaolin, waterglass and de-ionized water. The paste was molded into cylindrical rubber moulds (6  12 mm) and cured under different conditions: i.e. temperatures (ambient temperature, 37°C and 90°C), humidity and time (24, 48 and 96 hours). The compressive strength was determined using a universal testing machine. Helium pycnometer was used to measure the porosity. Via x-ray diffraction the phase composition of the cured samples was determined.

Elongated curing slightly decreased the total porosity of the tested geopolymers. Higher curing temperature increased the compressive strength after 24 hour but did not affect strength for longer curing times. In general, the samples cured in moisture had higher mechanical strength than those cured in air. But low compression strength of samples cured under high temperature and long time showed that some water content in geopolymer was essential to retaining its microstructure.

Place, publisher, year, edition, pages
John Wiley & Sons, 2013.
Series
Ceramic Engineering and Science Proceedings
National Category
Medical Materials
Identifiers
URN: urn:nbn:se:uu:diva-219258DOI: 10.1002/9781118807743.ch5OAI: oai:DiVA.org:uu-219258DiVA: diva2:698832
Conference
37th International Conference and Expo on Advanced Ceramics and Composites; 27 Jan - 1 Feb 2013; Daytona Beach, Fia., USA
Funder
Swedish Research Council
Available from: 2014-02-25 Created: 2014-02-25 Last updated: 2015-04-17Bibliographically approved
In thesis
1. Geopolymer-based drug formulations for oral delivery of opioids
Open this publication in new window or tab >>Geopolymer-based drug formulations for oral delivery of opioids
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Opioid therapy for chronic pain generally use controlled release formulations to deliver analgesic drugs around-the-clock. Controlled release dosage forms can enlarge the therapeutic effect by controlling the rate and site of release. However, with high drug content, opioid formulations are easily targeted for non-medical use. With the increasing concern of opioid abuse, tamper-resistance becomes an important attribute for opioid controlled-release dosage forms. Geopolymers have been studied as drug carrier for opioids to improve the tamper-resistance but there are still some issues, such as curing condition and fast drug release in acid, have not been studied in detail yet. This thesis focuses on the optimization and evaluation of the geopolymer-based formulation on its controlled-release and tamper-resistance properties with the aim of achieving optimal therapeutic outcomes and reducing abuse potential.

In this work, we showed some further improvement and evaluations on geopolymer-based drug formulations. The mechanical strength and porosity of geopolymers could be influenced by the curing conditions: high humidity for at least 48 hours could improve its mechanical strength, but elevated temperature only accelerated the geopolymerization but promoted water evaporation, leading to shrinkage and crack formation. Incorporating pH-sensitive organic polymers could improve the acid resistance of geopolymer formulation and thus reduce the risk of dose dumping. Comparing to a commercial opioid tablet, the geopolymer matrix have higher mechanical strength and could offer better resistance against physical manipulation and extraction under heating. The results provided solid experimental support on the potential for geopolymer as matrix for oral opioid delivery systems.

Place, publisher, year, edition, pages
Uppsala: Uppsala University, Department of Engineering Sciences, 2014
National Category
Medical Materials
Identifiers
urn:nbn:se:uu:diva-219259 (URN)
Presentation
2014-03-14, 13:28 (English)
Supervisors
Funder
Swedish Research Council
Available from: 2014-02-27 Created: 2014-02-25 Last updated: 2014-07-24Bibliographically approved
2. Ceramic Materials for Administration of Potent Drugs
Open this publication in new window or tab >>Ceramic Materials for Administration of Potent Drugs
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis aimed to investigate and document the potential of applying ceramics in two specific drug delivery applications: tamper-resistant opioid formulations and transdermal enhancement protrusions.

Geopolymers were developed into the matrix for a tamper-resistant formulation, aiming to protect drug substances from non-medical abuse. The synthesis conditions and excipients composition of the geopolymer-based formulation were modified in this work to facilitate a stable and extended drug delivery. Results showed that 37ºC 100% humidity for 48 hours were applicable conditions to obtain geopolymer with suitable mechanical strength and porosity. Moreover, it was found that the integration of poly(methyl acrylate) into the geopolymer-based formulation could reduce the drug release at low pH and, meanwhile, maintain the mechanical strength. Therefore, the geopolymer-based drug formulations concluded from these studies were applied in oral and transdermal delivery systems. Evidence of the tamper-resistance of geopolymer-based oral and transdermal formulations was documented and compared to the corresponding commercial opioid formulations. The results provided experimental support for the positive effects of geopolymers as drug carriers for the tamper-resistance of oral and transdermal delivery systems.

Self-setting bioceramics, calcium phosphate and calcium sulfate were fabricated into transdermal enhancement protrusions in this work for the first time. Results showed that, under mild conditions, both bioceramics could form pyramid-shaped needles in the micron size. The drug release from these needles could be controlled by the bulk surface area, porosity and degradation of the bioceramics. An in vitro insertion test showed that the bioceramic microneedles had enough mechanical strength to insert into skin. Further optimization on the geometry of needles and the substrate material was also performed. The higher aspect-ratio needles with a flexible and self-swellable substrate could release most of the drug content within 4 hours and could penetrate through the stratum corneum by manual insertion. This study explored the potential application of bioceramics in transdermal enhancement protrusions and showed promising indication of their future developments.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 65 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1235
Keyword
Tamper-resistance, Oral formulation, Transdermal formulation, Biomaterials, Microneedles
National Category
Biomaterials Science Ceramics
Identifiers
urn:nbn:se:uu:diva-245031 (URN)978-91-554-9188-8 (ISBN)
Public defence
2015-04-28, Polhemssalen, Lägerhyddsvägen 2, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2015-04-07 Created: 2015-02-24 Last updated: 2015-04-17

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Cai, BingEngqvist, HåkanBredenberg, SusanneMellgren, Torbjörn

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