Imperial College London

Professor Molly Stevens FREng

Faculty of EngineeringDepartment of Materials

Prof of Biomedical Materials&Regenerative Medicine
 
 
 
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Contact

 

+44 (0)20 7594 6804m.stevens

 
 
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Location

 

208Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

348 results found

Parak WJ, Chan WCW, Hafner JH, Hammond PT, Hersam MC, Javey A, Khademhosseini A, Kotov NA, Mulvaney P, Nel AE, Nordlander PJ, Penner RM, Rogach AL, Schaak RE, Stevens MM, Wee ATS, Willson CG, Weiss PSet al., 2013, Be critical but fair, ACS Nano, Vol: 7, Pages: 8313-8316, ISSN: 1936-0851

Journal article

Tang M, Purcell M, Steele JAM, Lee K-Y, McCullen S, Shakesheff KM, Bismarck A, Stevens MM, Howdle SM, Williams CKet al., 2013, Porous Copolymers of epsilon-Caprolactone as Scaffolds for Tissue Engineering, MACROMOLECULES, Vol: 46, Pages: 8136-8143, ISSN: 0024-9297

Journal article

de la Rica R, Stevens MM, 2013, Plasmonic ELISA for the detection of analytes at ultralow concentrations with the naked eye, NATURE PROTOCOLS, Vol: 8, Pages: 1759-1764, ISSN: 1754-2189

Journal article

Accardi MA, McCullen SD, Callanan A, Chung S, Cann PM, Stevens MM, Dini Det al., 2013, Effects of fiber orientation on the frictional properties and damage of regenerative articular cartilage surfaces, Tissue Engineering: Parts A, B, and C, Vol: 19, Pages: 2300-2310, ISSN: 1937-3368

Articular cartilage provides a low-friction, wear-resistant surface for diarthrodial joints. Due to overloading and overuse, articular cartilage is known to undergo significant wear and degeneration potentially resulting in osteoarthritis (OA). Regenerative medicine strategies offer a promising solution for the treatment of articular cartilage defects and potentially localized early OA. Such strategies rely on the development of materials to restore some aspects of cartilage. In this study, microfibrous poly(ɛ-caprolactone) scaffolds of varying fiber orientations (random and aligned) were cultured with bovine chondrocytes for 4 weeks in vitro, and the mechanical and frictional properties were evaluated. Mechanical properties were quantified using unconfined compression and tensile testing techniques. Frictional properties were investigated at physiological compressive strains occurring in native articular cartilage. Scaffolds were sheared along the fiber direction, perpendicular to the fiber direction and in random orientation. The evolution of damage as a result of shear was evaluated via white light interferometry and scanning electron microscopy. As expected, the fiber orientation strongly affected the tensile properties as well as the compressive modulus of the scaffolds. Fiber orientation did not significantly affect the equilibrium frictional coefficient, but it was, however, a key factor in dictating the evolution of surface damage on the surface. Scaffolds shear tested perpendicular to the fiber orientation displayed the highest surface damage. Our results suggest that the fiber orientation of the scaffold implanted in the joint could strongly affect its resistance to damage due to shear. Scaffold fiber orientation should thus be carefully considered when using microfibrous scaffolds.

Journal article

Boonrungsiman S, Fearn S, Gentleman E, Spillane L, Carzaniga R, McComb DW, Stevens MM, Porter AEet al., 2013, Correlative spectroscopy of silicates in mineralised nodules formed from osteoblasts, Nanoscale, Vol: 5, Pages: 7544-7551, ISSN: 2040-3372

Silicon supplementation has been shown to play an important role in skeleton development, however, the potential role that silicon plays in mediating bone formation, and an understanding of where it might localise in the resulting bone tissue remain elusive. An improved understanding of these processes could have important implications for treating pathological mineralisation. A key aspect of defining the role of silicon in bone is to characterise its distribution and coordination environment, however, there is currently almost no information available on either. We have combined a sample-preparation method that simultaneously preserved mineral, ions, and the extracellular matrix (ECM) with secondary ion mass spectroscopy (SIMS) and electron energy-loss spectroscopy (EELS) to examine the distribution and coordination environment of silicon in murine osteoblasts (OBs) in an in vitro model of bone formation. SIMS analysis showed a high level of surface contamination from polydimethysiloxane (PDMS) resulting from sample preparation. When the PDMS was removed, silicon compounds could not be detected within the nodules either by SIMS or by energy dispersive X-ray spectroscopy (EDX) analysis. In comparison, electron energy-loss spectroscopy (EELS) provided a powerful and potentially widely applicable means to define the coordination environment and localisation of silicon in mineralising tissues. We show that trace levels of silicon were only detectable from the mineral deposits located on the collagen and in the peripheral region of mineralised matrix, possibly the newly mineralised regions of the OB nodules. Taken together our results suggest that silicon plays a biological role in bone formation, however, the precise mechanism by which silicon exerts its physicochemical effects remains uncertain. Our analytical results open the door for compelling new sets of EELS experiments that can provide detailed and specific information about the role that silicates play in bone

Journal article

Bode F, da Silva MA, Smith P, Lorenz CD, McCullen S, Stevens MM, Dreiss CAet al., 2013, Hybrid gelation processes in enzymatically gelled gelatin: impact on nanostructure, macroscopic properties and cellular response, Soft Matter, Vol: 9, Pages: 6986-6999, ISSN: 1744-683X

Physical, chemical and hybrid tilapia fish gelatin hydrogels were investigated by small-angle neutron scattering (SANS), molecular dynamic simulations and their biological effect in cell cultures studied; results from the different experimental techniques were then correlated and linked to the rheological properties of the gels (F. Bode et al., Biomacromolecules, 2011, 12, 3741–3752). Hydrogels were obtained by cross-linking with the microbial enzyme transglutaminase (mTGase) under two conditions: above and below gelatin physical gelation temperature (ca. 23 °C). Hydrogels cross-linked at 37 °C, from the sol-state, are referred to as ‘chemical’ gels (C); hydrogels cross-linked at 21 °C, thus with concurrent physical gelation, are referred to as ‘physical-co-chemical’ gels (PC). The SANS data were appropriately described by a combination of a Lorentzian and a power law model. For physical gels, the correlation length (ξ) obtained from the fits decreased linearly with gelatin concentration, from 42 to 26 Å for 3.5 to 10% w/w gelatin, respectively. Independently of gelation temperature, all physical gels at a given concentration showed a similar correlation length ξ (26 ± 2 Å), with no significant difference with the sol-state (23 ± 2 Å). In both C and PC gels, ξ increased with mTGase concentration over the range studied: 40 to 167 Å for 10 and 40 U mTGase per g gelatin in C gels (after 120 min cross-linking) and 40 to 82 Å for 10 and 40 U mTGase per g gelatin for PC gels. ξ reached a plateau at the highest mTGase concentration studied for both types of gels. In addition, kinetic studies on C gels revealed that ξ increased linearly with time in the first two hours and grew faster with increasing mTGase concentration. ξ values in the PC gels were smaller than in the corresponding C gels. Cell proliferation studies showed that the gels were compatible with cell growth

Journal article

Bertazzo S, Gentleman E, Cloyd KL, Chester AH, Yacoub MH, Stevens MMet al., 2013, Nano-analytical electron microscopy reveals fundamental insights into human cardiovascular tissue calcification, Nature Materials, Vol: 12, Pages: 576-583, ISSN: 1476-4660

Journal article

Gentleman E, Stevens MM, Hill RG, Brauer DSet al., 2013, Surface properties and ion release from fluoride-containing bioactive glasses promote osteoblast differentiation and mineralization in vitro, Acta Biomaterialia, Vol: 9, Pages: 5771-5779, ISSN: 1878-7568

Journal article

Chung S, Gentilini C, Callanan A, Hedegaard M, Hassing S, Stevens MMet al., 2013, Responsive poly (gamma-glutamic acid) fibres for biomedical applications, JOURNAL OF MATERIALS CHEMISTRY B, Vol: 1, Pages: 1397-1401, ISSN: 2050-750X

Journal article

Hung A, Mager M, Hembury M, Stellacci F, Stevens MM, Yarovsky Iet al., 2013, Amphiphilic amino acids: a key to adsorbing proteins to nanopatterned surfaces?, CHEMICAL SCIENCE, Vol: 4, Pages: 928-937, ISSN: 2041-6520

Journal article

de Jonge LT, Stevens MM, 2013, Peptide nanotube coatings for bioapplications, Handbook of Biofunctional Surfaces, Pages: 569-590, ISBN: 9789814316637

Book chapter

Bonnell DA, Buriak JM, Chan WCW, Hafner JH, Hammond PT, Hersam MC, Javey A, Kotov NA, Nel AE, Nordlander PJ, Penner RM, Rogach AL, Schaak RE, Stevens MM, Wee ATS, Willson CG, Weiss PSet al., 2012, We take it personally, ACS Nano, Vol: 6, Pages: 10417-10419, ISSN: 1936-0851

Journal article

Pashuck ET, Stevens MM, 2012, Designing Regenerative Biomaterial Therapies for the Clinic, SCIENCE TRANSLATIONAL MEDICINE, Vol: 4, ISSN: 1946-6234

Journal article

de la Rica R, Stevens MM, 2012, Plasmonic ELISA for the ultrasensitive detection of disease biomarkers with the naked eye, Nature Nanotechnology, Vol: 7, Pages: 821-824, ISSN: 1748-3395

Journal article

Cloyd KL, El-Hamamsy I, Boonrungsiman S, Hedegaard M, Gentleman E, Sarathchandra P, Colazzo F, Gentleman MM, Yacoub MH, Chester AH, Stevens MMet al., 2012, Characterization of porcine aortic valvular interstitial cell 'calcified' nodules, PLOS One, Vol: 7, ISSN: 1932-6203

Valve interstitial cells populate aortic valve cusps and have been implicated in aortic valve calcification. Here we investigate a common in vitro model for aortic valve calcification by characterizing nodule formation in porcine aortic valve interstitial cells (PAVICs) cultured in osteogenic (OST) medium supplemented with transforming growth factor beta 1 (TGF-β1). Using a combination of materials science and biological techniques, we investigate the relevance of PAVICs nodules in modeling the mineralised material produced in calcified aortic valve disease. PAVICs were grown in OST medium supplemented with TGF-β1 (OST+TGF-β1) or basal (CTL) medium for up to 21 days. Murine calvarial osteoblasts (MOBs) were grown in OST medium for 28 days as a known mineralizing model for comparison. PAVICs grown in OST+TGF-β1 produced nodular structures staining positive for calcium content; however, micro-Raman spectroscopy allowed live, noninvasive imaging that showed an absence of mineralized material, which was readily identified in nodules formed by MOBs and has been identified in human valves. Gene expression analysis, immunostaining, and transmission electron microscopy imaging revealed that PAVICs grown in OST+TGF-β1 medium produced abundant extracellular matrix via the upregulation of the gene for Type I Collagen. PAVICs, nevertheless, did not appear to further transdifferentiate to osteoblasts. Our results demonstrate that ‘calcified’ nodules formed from PAVICs grown in OST+TGF-β1 medium do not mineralize after 21 days in culture, but rather they express a myofibroblast-like phenotype and produce a collagen-rich extracellular matrix. This study clarifies further the role of PAVICs as a model of calcification of the human aortic valve.

Journal article

McCullen SD, Autefage H, Callanan A, Gentleman E, Stevens MMet al., 2012, Anisotropic Fibrous Scaffolds for Articular Cartilage Regeneration, TISSUE ENGINEERING PART A, Vol: 18, Pages: 2073-2083, ISSN: 1937-3341

Journal article

Stevens MM, 2012, Keynote: New materials-based strategies for regenerative medicine, JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Vol: 6, Pages: 406-406, ISSN: 1932-6254

Journal article

Boonrungsiman S, Gentleman E, Carzaniga R, Evans ND, McComb DW, Porter AE, Stevens MMet al., 2012, The role of intracellular calcium phosphate in osteoblast-mediated bone apatite formation, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 109, Pages: 14170-14175, ISSN: 0027-8424

Journal article

de la Rica R, Aili D, Stevens MM, 2012, Enzyme-responsive nanoparticles for drug release and diagnostics, ADVANCED DRUG DELIVERY REVIEWS, Vol: 64, Pages: 967-978, ISSN: 0169-409X

Journal article

Bell NC, Minelli C, Tompkins J, Stevens MM, Shard AGet al., 2012, Emerging Techniques for Submicrometer Particle Sizing Applied to Stober Silica, LANGMUIR, Vol: 28, Pages: 10860-10872, ISSN: 0743-7463

Journal article

Rodriguez-Lorenzo L, de la Rica R, Alvarez-Puebla RA, Liz-Marzan LM, Stevens MMet al., 2012, Plasmonic nanosensors with inverse sensitivity by means of enzyme-guided crystal growth, Nature Materials, Vol: 11, Pages: 604-607, ISSN: 1476-4660

Journal article

Evans ND, Swain RJ, Gentleman E, Gentleman MM, Stevens MMet al., 2012, GENE-EXPRESSION ANALYSIS REVEALS THAT EMBRYONIC STEM CELLS CULTURED UNDER OSTEOGENIC CONDITIONS PRODUCE MINERAL NON-SPECIFICALLY COMPARED TO MARROW STROMAL CELLS OR OSTEOBLASTS, EUROPEAN CELLS & MATERIALS, Vol: 24, Pages: 211-223, ISSN: 1473-2262

Journal article

Place ES, Nair R, Chia HN, Szulgit G, Lim E-H, Stevens MMet al., 2012, Latent TGF-beta Hydrogels for Cartilage Tissue Engineering, ADVANCED HEALTHCARE MATERIALS, Vol: 1, Pages: 480-484, ISSN: 2192-2640

Journal article

Bonzani IC, Campbell JJ, Knight MM, Williams A, Lee DA, Bader DL, Stevens MMet al., 2012, Dynamic compressive strain influences chondrogenic gene expression in human periosteal cells: A case study, JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, Vol: 11, Pages: 72-81, ISSN: 1751-6161

Journal article

Gentilini C, Dong Y, May JR, Goldoni S, Clarke DE, Lee B-H, Pashuck ET, Stevens MMet al., 2012, Functionalized Poly(gamma-Glutamic Acid) Fibrous Scaffolds for Tissue Engineering, ADVANCED HEALTHCARE MATERIALS, Vol: 1, Pages: 308-315, ISSN: 2192-2640

Journal article

Stevens MM, Mecklenburg G, 2012, Bio-inspired materials for biosensing and tissue engineering, POLYMER INTERNATIONAL, Vol: 61, Pages: 680-685, ISSN: 0959-8103

Journal article

Bertazzo S, von Erlach T, Goldoni S, Candarhoglu PL, Stevens MMet al., 2012, Correlative light-ion microscopy for biological applications, Nanoscale, Vol: 4, Pages: 2851-2854, ISSN: 2040-3372

Journal article

Bonnell DA, Hafner JH, Hersam MC, Kotov NA, Buriak JM, Hammond PT, Javey A, Nordlander P, Parak WJ, Schaak RE, Wee ATS, Weiss PS, Rogach AL, Stevens MM, Willson CGet al., 2012, Recycling is not always good: the dangers of self-plagiarism., ACS Nano, Vol: 6, Pages: 1-4

Journal article

Poologasundarampillai G, Yu B, Tsigkou O, Valliant E, Yue S, Lee PD, Hamilton RW, Stevens MM, Kasuga T, Jones JRet al., 2012, Bioactive silica-poly(gamma-glutamic acid) hybrids for bone regeneration: effect of covalent coupling on dissolution and mechanical properties and fabrication of porous scaffolds, SOFT MATTER, Vol: 8, Pages: 4822-4832, ISSN: 1744-683X

Journal article

Lowe SB, Dick JAG, Cohen BE, Stevens MMet al., 2012, Multiplex Sensing of Protease and Kinase Enzyme Activity via Orthogonal Coupling of Quantum Dot Peptide Conjugates, ACS NANO, Vol: 6, Pages: 851-857, ISSN: 1936-0851

Journal article

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