My research is centered around the preparation and development of porous inorganic structures suitable for use as implant materials such as artificial bones and teeth, as supports for drug delivery or as catalysts or catalyst supports. Previously I have employed various approaches to the preparation of these materials including the use of crystal altering additives in solution, microemulsions, carbonated water systems or other gas releasing reactions or sacrificial dextran templates. This research has included collaborations with NIMS Institute in Tsukuba, Japan, with the NCCR Institute, Osaka, Japan, the University of Bologna, Italy and the Orthopaedics Unit at Southampton University.
Some specific highlights in the research include the preparation of calcium phosphate bone mimic reticulated structures by the mineralization of water channels within a water/oil continuous microemulsion. Porous calcium carbonate spherical sponges were also prepared from mineralizing emulsion system and this system was also used to prepare hollow spherical clay structures. More recently metallic silver and gold foams were formed from dextran/metal salt mixtures that were heated to remove the organic component. A development of this principle was the preparation of frameworks of zeolite crystals contained within interlocked silica fibres. More recently sponge films of ?-tricalcium phosphate bioceramic were prepared by a controlled precipitation at the air/water interface from a carbonated water mineralizing system.
Currently, as an EPSRC Advanced Research Fellow I am investigating the use of cold isotatic presssing (CIP) for the preparation of bioceramic tissue scaffolds suitable for cell seeding and also the preparation of catalysts and catalyst supports with an application in fuel cells. Overal CIP is a novel approach and suitable for scaling up for large scale production.
*Walsh D, Boanini E, Tanaka J, Mann S, Synthesis of tri-calcium phosphate sponges by interfacial deposition and thermal transformation of self-supporting calcium phosphate films, J Mat Chem 15, 1043-1048, 2005
Gonzalez-McQuire R, Green D, Walsh D, Hall S, Chane-Ching JY, Oreffo ROC, Mann S, Fabrication of hydroxyapatite sponges by dextran sulphate/amino acid templating, Biomaterials, 26, 6652-6656, 2005.
Green DW, Leveque I, Walsh D, Howard D, Yang XB, Partridge K, Mann S, Oreffo ROC, Biomineralized polysaccharide capsules for encapsulation, organization, and delivery of human cell types and growth factors, Adv. Func. Mat., 15, 917-923, 2005.
Furuzono T, Walsh D, Yasuda S, Sato K, Tanaka J, Kishida A, Preparation of plated beta-tricalcium phosphate containing hydroxyapatite for use in bonded inorganic-organic composites, J. Mat. Sci. 40, 2595-2597, 2005.
*Walsh D, Kulak A, Aoki K, Ikoma T, Tanaka J, Mann S, Preparation of higher-order zeolite materials using dextran templating, Angew Chem, Int. Ed. 43, 6691-6695, 2004
Green D, Walsh D, Yang X, Mann S, Oreffo ROC, Stimulation of human bone marrow stromal cells using growth factor encapsulated calcium carbonate porous microspheres, J Mat Chem 14, 2206-2212, 2004
*Walsh D, Arcelli L, Ikoma T, Tanaka J, Mann S, Dextran templating for the synthesis of metallic and metal oxide sponges, Nature Materials (2) 386-390 2003
Green DW, Walsh D, Partridge KA, Mann S, Oreffo ROC Mineral biomimicry generation of biomimetic microporous calcium carbonate spheres for skeletal regeneration, J of Bone and Min Res 18 (7): 1369-1369 2003
Ikoma T, Kobayashi H, Tanaka J, Walsh D, Mann S, Microstructure, mechanical, and biomimetic properties of fish scales from Pagrus major, Jr. Struct. Biol. 142 (3) 327-333 2003
Green DW, Leveque I, Walsh D, Partridge KA, Mann S, Oreffo RO, Innovative biomineralised polysaccharide templates for human bone cell and gene delivery, J of Bone and Min Res. 18 (7): 1361-1361 2003
Hall SR, Walsh D, Green D, Oreffo R, Mann S, A novel route to highly porous bioactive silica gels, J. Mater. Chem. 13(2) 186-190, 2003
Muthusamy E, Walsh D, Mann S, Morphosynthesis of organoclay microspheres with spongelike or hollow interiors, Adv Mater. (14) 969-972, 2002
Bigi A, Boanini E, Walsh D, Mann S, Morphosynthesis of octacalcium phosphate hollow microspheres by polyelectrolyte-mediated crystallization, Angew. Chem. Int. Ed. 41(12) 2163-2166, 2002
Green D, Walsh D, Mann S, Oreffo R, The potential of biomimesis in bone tissue engineering: Lessons from design and synthesis of invertebrate skeletons, Bone (30) 810-815, 2002
*Walsh D, Furuzono T, Tanaka J, Preparation of porous composite implant materials by in situ polymerisation of porous apatite containing ?-caprolactone or methyl methacrylate, Biomaterials (22) 1205-1212, 2001
*Walsh D, Tanaka J, Preparation of a bone-like apatite foam cement, J Mat Sci: Mat in Med (12) 1-5, 2001
Furuzono T, Walsh D, Sato K, Sonoda K, Tanaka J, Effect of reaction temperature on the morphology and size of hydroxyapatite nanoparticles in an emulsion system, J. Mat. Sci. Lett. (20) 111-114, 2001
*Walsh D, Chapter 1: Morphology and Structure; Section 5: From Biomineralization to Biomimetics. In: Handbook of Biomimetics, NTS Inc., Tokyo, Japan, p58-69, 2000 (Japanese).
*Walsh D, Lebeau B, Mann S, Morphosynthesis of calcium carbonate (vaterite) microsponges, Adv Mater 11: (4) 324-328 Mar 4 1999
Antonietti M, Breulmann M, Goltner CG, Colfen H, Wong KKW, Walsh D, Mann S, Inorganic/organic mesostructures with complex architectures: Precipitation of calcium phosphate in the presence of double-hydrophilic block copolymers, Chemistry-A European Journal 4: (12) 2493-2500 Dec 1998
Sims SD, Walsh D, Mann S, Morphosynthesis of macroporous silica frameworks in bicontinuous microemulsions, Adv Mater 10: (2) 151, Jan 22 1998
Breulmann M, Colfen H, Hentze HP, Antonietti M, Walsh D, Mann S, Elastic magnets: Template-controlled mineralization of iron oxide colloids in a sponge-like gel matrix, Adv Mater 10: (3) 237 Feb 11 1998
Mann S, Burkett SL, Davis SA, Fowler CE, Mendelson NH, Sims SD, Walsh D, Whilton NT, Sol-gel synthesis of organized matter, Chem of Mater 9: (11) 2300-2310 Nov 1997
*Walsh D, Mann S, Synthesis of cellular inorganic films from self-organzied media, Adv Mater 9: (8) 658-662 Jun 1997
Mann S, Walsh D, Feigning nature’s sculptures, Chem Brit 32: (11) 31-34 Nov 1996
*Walsh D, Mann S, Chemical synthesis of microskeletal calcium phosphate in bicontinuous microemulsions, Chem Mater 8: (8) 1944-1953 Aug 1996
*Walsh D, Mann S, Fabrication of hollow porous shells of calcium carbonate from self-organizing media, Nature 377: (6547) 320-323 Sep 28 1995
*Walsh D, Hopwood JD, Mann S, Crystal tectonics-Construction of reticulated calcium phosphate frameworks in bicontinous microemulsions, Science 264: (5165) 1576-1578 Jun 10 1994
*Walsh D, Kingston JL, Heywood BR, Mann S, Influence of monosaccharides and related molecules on the morphology of hydroxyapatite, J Cryst Growth 133: (1-2) 1-12 Oct 1993
*Walsh D, Arcelli L, Ikoma T, Tanaka J, Mann S, Metal or metal oxide porous material and catalyst, prepared by use of dextran or related soluble carbohydrate polymer as an agent to form porous three dimensional architectures from metal salts or preformed particles, JST CREST (Japan) Patent PCT/JPO2/13183 (2002), 02-F-002US/NT (United States 2005) and 02808253.5-2104-JP0213183 (Europe).
*Walsh D, Mann S, Hair mineralization treatment, Bristol University/ L’Oreal Patent 2000.
*Walsh D, Mann S, Preparation of porous ceramic microspheres, Bath University/ ECC Patent 1997.
1/7/2005 EPSRC Advanced Research Fellowship, Novel routes to porous ceramic scaffolds by use of cold isostatic pressing and dextran templating, (5 years), PI D. Walsh.
14/1/2003 ICYS Fellowship (Japan), Preparation of porous implant materials, (1 year), PI D. Walsh.
Invited speaker to several International Conferences in Japan and UK
Including:
MRS-J ICAM 2003 Conference, Yokohama, October 2003
AsiaNano 2002 Conference, Tokyo November 2002
IThe 8th International Symposium on Biomineralization, Kurokawa, Niigata, Japan, September 2001.
Young Scientist Reviewer for the journal Biomaterials and author for a chapter on biomimetic chemistry in the Handbook of Biomaterials (NTS Inc. Publishers, 2000).