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Department of Physical Chemistry

Drug Delivery, or in a broader sense delivery of different biologically active agents such as drug molecules, therapeutic proteins and viruses, is the fastest growing segment of the biomaterials research. This is partly due to new and emerging therapeutic methods that include, for example, the delivery of biotechnically produced proteins and viral-vector delivery for gene therapy. Another challenge is to improve the delivery of many conventional drugs. The delivery is often impractical (e.g. several injections daily) or ineffective (absorption is low). By using a drug delivery device, in which the biologically active agents are encapsulated, many problems can be solved. A drug delivery device can be used in oral delivery, but the main application is as a device that is implanted in tissue. The device may include several months’ dose and release the molecules at a suitable rate. The device may also protect proteins from too early degradation, or therapeutic viruses from too early immune response. In addition, the local delivery of drugs is often desired, e.g. due to better local effect against tumors or to reduce harmful side effects. These challenges are met in the Functional Porous Materials group at the Åbo Akademi University by utilising the long research tradition on sol-gel-derived bioceramics. Sol-gel-derived SiO2, which is known to be biocompatible, is one of the potential delivery device materials for many types of biologically active agents. Sol-gel technology is a synthetic method to prepare ceramics. It is done at a low temperature in liquid phase that allows easy addition of different biologically active agents during the synthesis. First, SiO2 nanoparticles form, they grow in size and simultaneously aggregate and encapsulate added drug molecules. Optionally, drugs can be absorbed afterwards into a ready-made SiO2. Depending on the synthesis parameters, different threedimensional structures can be formed.

Control over the porous structure that typically matches the size of different drug molecules (0.5-100nm) and adjustable biodegradation are the main topics of development. Adjustable biodegradation is important, especially for larger biologically active agents, like proteins and viruses. They are sensitive to temperature and pH, which is challenging for the SiO2 sol-gel process. A nanotechnology approach is used to adjust the pore structure. The tendency of amphiphilic molecules to form micelles and a larger supramolecular structure is utilised. Micelle size and structure can be adjusted and used as a three-dimensional guide for reacting silica species in liquid. This process results in precise pore sizes that can be adjusted according to drug molecules. The pore walls can be additionally functionalised for desired interaction with drug molecules. Furthermore, magnetic nanoparticles and/or fluorophores are typically incorporated into the particles or attached covalently to the particle surface, which allows the particles to be localized in vitro and in vivo. Currently, we are focusing a lot of effort on the attachment of selective targeting ligands to the particles for targeted drug delivery and diagnostics applications. This work has resulted in several academic publications and theses. The work is financed by several domestic research and technology agencies, the European Union, as well as several companies.

Main topics of Research
Synthesis, physicochemical
characerization, and application of
porous and non-porous
silicas and calcium phosphates
as drug, and gene delivery supports, with the
aim of defining structure-performance
relationships on multiple
length scales.

Research Group
Department of Physical Chemistry:
8 researchers have been active in
the field of  sol-gel derived biomaterials
during the years 2003-2008

Publications on Sol-Gel Derived Biomaterials
2003-2008: 21

Doctoral Theses: 4

Contact Information
Mika Lindén, PhD
Department of Physical Chemistry,
Åbo Akademi University,
Porthaninkatu 3-5
FI-20500 Turku, Finland
Tel. +358 (0)2 2154297
Mobile +358 (0) 40 569 2861
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.