1
|
Nadarassan D, Loni A, Canham LT, Scoutaris N, Trivedi V, Douroumis D. Ultrahigh nanostructured drug payloads from degradable mesoporous silicon aerocrystals. Int J Pharm 2021; 607:120840. [PMID: 34245843 DOI: 10.1016/j.ijpharm.2021.120840] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/27/2021] [Accepted: 06/28/2021] [Indexed: 11/15/2022]
Abstract
Porous silicon has found increased attention as a drug delivery system due to its unique features such as high drug payloads, surface area and biodegradation. In this study supercritical fluid (SCF) assisted drying of ultrahigh porosity (>90%) silicon particles and flakes was shown to result in much higher mesopore volumes (~4.66 cm3/g) and surface areas (~680 m2/g) than with air-drying. The loading and physical state of the model drug (S)-(+)-Ibuprofen in SCF dried matrices was quantified and assessed using thermogravimetric analysis, differential scanning calorimetry, UV-Vis spectrophotometry, gravimetric analysis, gas adsorption and electron microscopy. Internal drug payloads of up to 72% were achieved which was substantially higher than values published for both conventionally dried porous silicon (17-51%) and other mesoporous materials (7-45%). In-vitro degradability kinetics of SCF-dried matrices in simulated media was also found to be faster than air-dried controls. The in-vitro release studies provided improved but sustained drug dissolution at both pH 2.0 and pH 7.4.
Collapse
Affiliation(s)
- D Nadarassan
- pSiMedica Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ, UK
| | - A Loni
- pSiMedica Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ, UK
| | - L T Canham
- pSiMedica Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ, UK; School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - N Scoutaris
- Faculty of Engineering of Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - V Trivedi
- Medway School of Pharmacy, University of Kent, Medway Campus, Central Avenue, Chatham Maritime, Chatham, Kent ME4 4TB, United Kingdom
| | - D Douroumis
- Faculty of Engineering of Science, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| |
Collapse
|
2
|
Sahare P, Ayala M, Vazquez-Duhalt R, Pal U, Loni A, Canham LT, Osorio I, Agarwal V. Enhancement of Peroxidase Stability Against Oxidative Self-Inactivation by Co-immobilization with a Redox-Active Protein in Mesoporous Silicon and Silica Microparticles. Nanoscale Res Lett 2016; 11:417. [PMID: 27650291 PMCID: PMC5030200 DOI: 10.1186/s11671-016-1605-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/31/2016] [Indexed: 06/06/2023]
Abstract
The study of the stability enhancement of a peroxidase immobilized onto mesoporous silicon/silica microparticles is presented. Peroxidases tend to get inactivated in the presence of hydrogen peroxide, their essential co-substrate, following an auto-inactivation mechanism. In order to minimize this inactivation, a second protein was co-immobilized to act as an electron acceptor and thus increase the stability against self-oxidation of peroxidase. Two heme proteins were immobilized into the microparticles: a fungal commercial peroxidase and cytochrome c from equine heart. Two types of biocatalysts were prepared: one with only covalently immobilized peroxidase (one-protein system) and another based on covalent co-immobilization of peroxidase and cytochrome c (two-protein system), both immobilized by using carbodiimide chemistry. The amount of immobilized protein was estimated spectrophotometrically, and the characterization of the biocatalyst support matrix was performed using Brunauer-Emmett-Teller (BET), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared (FTIR) analyses. Stability studies show that co-immobilization with the two-protein system enhances the oxidative stability of peroxidase almost four times with respect to the one-protein system. Thermal stability analysis shows that the immobilization of peroxidase in derivatized porous silicon microparticles does not protect the protein from thermal denaturation, whereas biogenic silica microparticles confer significant thermal stabilization.
Collapse
Affiliation(s)
- P. Sahare
- Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autónoma del Estado de México, Av. Univ. 1001, Col. Chamilpa, Cuernavaca, Morelos 62209 Mexico
| | - M. Ayala
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, Cuernavaca, 62210 Morelos Mexico
| | - R. Vazquez-Duhalt
- Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de Mexico, Km. 107, Carretera Tijuana-Ensenada, Apdo. Postal 14, CP 22800 Ensenada, Baja California Mexico
| | - U. Pal
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - A. Loni
- pSiMedica Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ UK
| | - L. T. Canham
- pSiMedica Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ UK
| | - I. Osorio
- Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - V. Agarwal
- Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autónoma del Estado de México, Av. Univ. 1001, Col. Chamilpa, Cuernavaca, Morelos 62209 Mexico
| |
Collapse
|
3
|
Abstract
In the 1970s, several studies revealed the requirement for silicon in bone development, while bioactive silicate glasses simultaneously pioneered the current era of bioactive materials. Considerable research has subsequently focused on the chemistry and biological function of silicon in bone, demonstrating that the element has at least two separate effects in the extracellular matrix: (i) interacting with glycosaminoglycans and proteoglycans during their synthesis, and (ii) forming ionic substitutions in the crystal lattice structure of hydroxyapatite. In addition, the dissolution products of bioactive glass (predominantly silicic acids) have significant effects on the molecular biology of osteoblasts in vitro, regulating the expression of several genes including key osteoblastic markers, cell cycle regulators and extracellular matrix proteins. Researchers have sought to capitalize on these effects and have generated a diverse array of biomaterials, which include bioactive glasses, silicon-substituted hydroxyapatites and pure, porosified silicon, but all these materials share similarities in the mechanisms that result in their bioactivity. This review discusses the current data obtained from original research in biochemistry and biomaterials science supporting the role of silicon in bone, comparing both the biological function of the element and analysing the evolution of silicon-containing biomaterials.
Collapse
Affiliation(s)
- J R Henstock
- Institute for Science and Technology in Medicine, Keele University, Stoke-on-Trent ST4 7QB, UK.
| | - L T Canham
- pSiMedica Ltd, Malvern Hills Science Park, Malvern, Worcestershire WR14 3SZ, UK
| | - S I Anderson
- University of Nottingham School of Medicine, Division of Medical Science and Graduate Entry Medicine, Royal Derby Hospital Centre, Uttoxeter Road, Derby DE22 3DT, UK
| |
Collapse
|
4
|
Henstock JR, Ruktanonchai UR, Canham LT, Anderson SI. Porous silicon confers bioactivity to polycaprolactone composites in vitro. J Mater Sci Mater Med 2014; 25:1087-1097. [PMID: 24398914 DOI: 10.1007/s10856-014-5140-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 01/02/2014] [Indexed: 06/03/2023]
Abstract
Silicon is an essential element for healthy bone development and supplementation with its bioavailable form (silicic acid) leads to enhancement of osteogenesis both in vivo and in vitro. Porous silicon (pSi) is a novel material with emerging applications in opto-electronics and drug delivery which dissolves to yield silicic acid as the sole degradation product, allowing the specific importance of soluble silicates for biomaterials to be investigated in isolation without the elution of other ionic species. Using polycaprolactone as a bioresorbable carrier for porous silicon microparticles, we found that composites containing pSi yielded more than twice the amount of bioavailable silicic acid than composites containing the same mass of 45S5 Bioglass. When incubated in a simulated body fluid, the addition of pSi to polycaprolactone significantly increased the deposition of calcium phosphate. Interestingly, the apatites formed had a Ca:P ratio directly proportional to the silicic acid concentration, indicating that silicon-substituted hydroxyapatites were being spontaneously formed as a first order reaction. Primary human osteoblasts cultured on the surface of the composite exhibited peak alkaline phosphatase activity at day 14, with a proportional relationship between pSi content and both osteoblast proliferation and collagen production over 4 weeks. Culturing the composite with J744A.1 murine macrophages demonstrated that porous silicon does not elicit an immune response and may even inhibit it. Porous silicon may therefore be an important next generation biomaterial with unique properties for applications in orthopaedic tissue engineering.
Collapse
Affiliation(s)
- J R Henstock
- Institute for Science and Technology in Medicine, Keele University, Stoke-on-Trent, ST4 7QB, UK,
| | | | | | | |
Collapse
|
5
|
Bowditch AP, Waters K, Gale H, Rice P, Scott EAM, Canham LT, Reeves CL, Loni A, Cox. TI. In-Vivo Assessment of Tissue Compatibility and Calcification of Bulk and Porous Silicon. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-536-149] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractThe compatibility of both bulk and porous silicon at the subcutaneous site has been assessed for the first time, following ISO standard procedures. The in-vivo responses to implantation were monitored in the guinea pig and histopathological reactions evaluated at 1, 4, 12 and 26 weeks. Attention is focused here on the histological assessment protocols used, and the results demonstrating in-vivo evidence for good tissue compatibility, and porous Si bioactivity with regards calcification.
Collapse
|
6
|
Abstract
ABSTRACTThe spectroscopic evidence that the main visible photoluminescence (PL) band of porous silicon (the 'S' band) originates from quantum confined crystalline silicon is presented, and arguments that claim to invalidate this evidence are analysed in detail. We find that a careful study of all the spectroscopic data provides strong support for the quantum confinement model. Additionally we consider the interesting issue of the luminescence spectrum of a single silicon quantum dot.
Collapse
|
7
|
Abstract
ABSTRACTThis detailed electron microscope study of porous silicon compares the different structures of macro-, meso- and microporous material. Mesoporous silicon of high porosity (∼-80%) exhibits efficient red photoluminescence at room temperature. Transmission electron microscopy provides strong direct evidence that this visible luminescence arises from dramatic carrier confinement in quantum-size, crystalline silicon structures. Images of undulating, interconnected ‘quantum wires’ of widths <3nm are shown.
Collapse
|
8
|
Canham LT, Reeves CL, Wallis DJ, Newey JP, Houlton MR, Sapsford GJ, Godfrey RE, Loni A, Simons AJ, Cox TI, Ward MCL. Silicon as an Active Biomaterial. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-452-579] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractThe response of a range of porous Si and poly Si films to storage in acellular simulated body fluids is summarised and its implications discussed. It is suggested that the combination of VLSI technology, micromachining and surface microstructuring achievable with silicon, could establish this prominent semiconductor as a very useful biomaterial by the next century. The ‘biocompatibility’ of a variety of silicon microstructures, and even bulk silicon has received surprisingly little study, but now warrants detailed in-vitro and in-vivo assessment.
Collapse
|
9
|
Simons AJ, Cox TI, Loni A, Calcott PDJ, Uren MJ, Canham LT. A Study of the Factors Which Determine the Modulation Speed of a Shallow PN Junction Porous Silicon Led. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-452-693] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractThe effect of the chemical thinning of the porous silicon structure on the speed and efficiency of electroluminescent devices, produced by the anodisation of a pn junction in bulk silicon is investigated. Thinning of the silicon wires results in an increase in the efficiency but at the expense of a reduction in operating speed. It is demonstrated that the operating speed is limited by the photoluminescence lifetime for small signal excitation. However, for large signals, the electroluminescence can be turned off more than 5 times faster than the photoluminescence lifetime, indicating that this need not necessarily limit device operating speed.
Collapse
|
10
|
Abstract
AbstractThe response of a range of porous Si films to acellular simulated body fluids has been monitored by SEM, EDX and FTIR analyses. Quite low levels of porosity are shown here to induce hydroxyapatite growth both on top of the film, and even on neighbouring areas of bulk Si, which in isolation have no such effect. The in-vitro demonstration of hydroxyapatite nucleation by a porous semiconductor could provide further insight into the phenomenon of bioactivity and help realise a broader range of bioactive materials.
Collapse
|
11
|
Abstract
AbstractPorous semiconductors constitute a class of material that exhibit surprising properties, are quite easy to fabricate, but are however fragile, complex, and difficult to characterise. This tutorial review extracts specific topics from the large knowledge base now available on porous Si that are deemed relevant to other porous semiconductors beginning to receive study. It also highlights topics where controversy is now resolved, where problems remain, and where further effort could be focused.
Collapse
|
12
|
Abstract
ABSTRACTMicroporous silicon layers contain an enormous surface area (> 500 m2 cm−3) that influences their structural, optical and electrical properties. When freshly etched the pore wall surface can be extremely clean and composed primarily of hydrogen and fluorine. Extended storage in ambient air however will convert this clean hydride surface into that of a contaminated native oxide.Using dynamic SIMS profiling we demonstrate here that slow oxidation at room temperature by ambient air is accompanied by impregnation with atmospheric boron and sulphur but that levels of calcium and sodium for example, remain exceedingly low. We conclude that the pore wall surface is very efficiently protected from particulate - related airborne species but is susceptible to contamination from small molecules present in the atmosphere at trace levels.
Collapse
|
13
|
Anderson SHC, Elliott H, Wallis DJ, Canham LT, Powell JJ. Dissolution of different forms of partially porous silicon wafers under simulated physiological conditions. ACTA ACUST UNITED AC 2003. [DOI: 10.1002/pssa.200306519] [Citation(s) in RCA: 202] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
14
|
Wainwright M, Canham LT, al-Wajeeh K, Reeves CL. Morphological changes (including filamentation) in Escherichia coli grown under starvation conditions on silicon wafers and other surfaces. Lett Appl Microbiol 1999; 29:224-7. [PMID: 10583748 DOI: 10.1046/j.1365-2672.1999.00602.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Using a scanning electron microscope, pleomorphism (notably filamentation) was seen when Escherichia coli was grown under starvation conditions for 14 d on microporous silicon wafers, titanium, glass and plastic discs. Under these conditions, the 'standard', rod shaped cell (1-3 microns) failed to separate after division and filaments developed, some as long as 50 microns, with many showing bulbous tips. Filamentation began to occur 5 d after the imposition of starvation conditions. Dumbbell shaped cells were also observed, although apparent 'Y' and 'V'-shaped cells proved to be artefacts, caused by overlapping rods. The implications of the appearance of pleomorphism in E. coli, when grown under starvation conditions, is discussed in relation to its pathogenicity and growth in the environment.
Collapse
Affiliation(s)
- M Wainwright
- Department of Molecular Biology and Biotechnology, University of Sheffield, UK
| | | | | | | |
Collapse
|
15
|
Hamilton B, Jacobs J, Hill DA, Pettifer RF, Teehan D, Canham LT. Size-controlled percolation pathways for electrical conduction in porous silicon. Nature 1998. [DOI: 10.1038/30924] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
16
|
Nash KJ, Calcott PD, Canham LT, Needs RJ. Spin-orbit interaction, triplet lifetime, and fine-structure splitting of excitons in highly porous silicon. Phys Rev B Condens Matter 1995; 51:17698-17707. [PMID: 9978801 DOI: 10.1103/physrevb.51.17698] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
|
17
|
Needs RJ, Bhattacharjee S, Nash KJ, Qteish A, Read AJ, Canham LT. First-principles calculations of band-edge electronic states of silicon quantum wires. Phys Rev B Condens Matter 1994; 50:14223-14227. [PMID: 9975643 DOI: 10.1103/physrevb.50.14223] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
|
18
|
Canham LT, Cullis AG, Pickering C, Dosser OD, Cox TI, Lynch TP. Luminescent anodized silicon aerocrystal networks prepared by supercritical drying. Nature 1994. [DOI: 10.1038/368133a0] [Citation(s) in RCA: 170] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
19
|
Read AJ, Needs RJ, Nash KJ, Canham LT, Calcott PD, Qteish A. First-principles calculations of the electronic properties of silicon quantum wires. Phys Rev Lett 1992; 69:1232-1235. [PMID: 10047161 DOI: 10.1103/physrevlett.69.1232] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
|
20
|
|