Biox Systems Ltd.

London, United Kingdom

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London, United Kingdom
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Xiao P.,London South Bank University | Xiao P.,Biox Systems Ltd | Imhof R.E.,Biox Systems Ltd
International Journal of Pharmaceutics | Year: 2012

Solvents penetration through in vivo human stratum corneum (SC) has always been an interesting research area for trans-dermal drug delivery studies, and the importance of intercellular routes (diffuse in between corneocytes) and transcellular routes (diffuse through corneocytes) during diffusion is often debatable. In this paper, we have developed a two dimensional finite element model to simulate the dynamic water diffusion through the SC. It is based on the brick-and-mortar model, with brick represents corneocytes and mortar represents lipids, respectively. It simulates the dynamic water diffusion process through the SC from pre-defined initial conditions and boundary conditions. Although the simulation is based on water diffusions, the principles can also be applied to the diffusions of other topical applied substances. The simulation results show that both intercellular routes and transcellular routes are important for water diffusion. Although intercellular routes have higher flux rates, most of the water still diffuse through transcellular routes because of the high cross area ratio of corneocytes and lipids. The diffusion water flux, or trans-epidermal water loss (TEWL), is reversely proportional to corneocyte size, i.e. the larger the corneocyte size, the lower the TEWL, and vice versa. There is also an effect of the SC thickness, external air conditions and diffusion coefficients on the water diffusion through SC on the resulting TEWL. © 2012 Elsevier B.V. All rights reserved.


Xiao P.,London South Bank University | Xiao P.,Biox Systems Ltd. | Zheng X.,London South Bank University | Zheng X.,Biox Systems Ltd. | And 2 more authors.
International Journal of Pharmaceutics | Year: 2011

This work describes the first application of Opto-Thermal Transient Emission Radiometry (OTTER), an infrared remote sensing technique, to probe the extent to which solvents permeate the human nail in vivo. Decanol, glycerol and butyl acetate were selected as model solvents. After application of the solvents, individually, to human volunteers, OTTER was used to depth profile the solvents. The permeation rate of the solvents was ranked as glycerol > decanol > butyl acetate. It is possible that some of the butyl acetate may have evaporated during the experiment. The ability of decanol to extract lipids from biological tissue is also considered. These preliminary results demonstrate the potential of OTTER as a tool to identify optimal excipients with which to target drugs to the nail. © 2011 Elsevier B.V. All rights reserved.


Xiao P.,London South Bank University | Xiao P.,Biox Systems Ltd | Wong W.,Hong Kong Sanatorium and Hospital | Cottenden A.M.,University College London | Imhof R.E.,Biox Systems Ltd
International Journal of Cosmetic Science | Year: 2012

Skin over-hydration is a common problem that affects many people who wear incontinence pads or diapers. The aim of this study is to develop a new method for stratum corneum (SC) over-hydration and SC water diffusion coefficient measurements using opto-thermal transient emission radiometry (OTTER) and evaporimetry. With OTTER, we can measure the SC surface hydration and hydration gradient. With evaporimetry, we can measure the time-dependent evaporative drying curves of water vapour flux density (WVFD). The combination of hydration results and WVFD results can yield information on the SC water diffusion coefficient and how it depends on the SC surface hydration level. The results show that SC water diffusion coefficient is non-linearly proportional to the SC surface hydration level. The results also show strong correlations between evaporative drying flux measured using the Evaporimeter and surface hydration estimated from OTTER measurements. © 2012 The Authors. ICS © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.


Cui Y.,London South Bank University | Xiao P.,London South Bank University | Xiao P.,Biox Systems Ltd. | Imhof R.E.,Biox Systems Ltd.
International Journal of Thermophysics | Year: 2013

Stratum corneum is the outermost skin layer, and the water content in stratum corneum plays a key role in skin cosmetic properties as well as skin barrier functions. However, tomeasure the water content, especially the water concentration depth profile, within stratum corneum is very difficult. Opto-thermal emission radiometry, or OTTER, is a promising technique that can be used for such measurements. In this paper, a study on stratum corneum hydration depth profiling by using a genetic algorithm (GA) is presented. The pros and cons of a GA compared against other inverse algorithms such as neural networks, maximum entropy, conjugate gradient, and singular value decomposition will be discussed first. Then, it will be shown how to use existing knowledge to optimize a GA for analyzing the opto-thermal signals. Finally, these latestGAresults on hydration depth profiling of stratum corneum under different conditions, as well as on the penetration profiles of externally applied solvents, will be shown. © Springer Science+Business Media New York 2013.


Xiao P.,London South Bank University | Xiao P.,Biox Systems Ltd | Ciortea I.L.,Biox Systems Ltd | Singh H.,London South Bank University | And 4 more authors.
Journal of Physics: Conference Series | Year: 2010

We compared five different skin hydration measurement techniques, namely OTTER, Fingerprint sensors, Corneometer, Nova, and Moisture Checker, in order to understand the correlations between different skin hydration measurement techniques and to understand the repeatability of each technique. The measurements are performed on different in-vivo skin sites from different volunteers and at different hydration levels. The repeatability of different techniques is achieved by measuring the same skin site repeatedly. The correlations between different skin hydration measurement techniques are achieved by plotting results from different techniques against each other. The different skin hydration levels are achieved through the recovery period after a skin immersive hydration. © 2010 IOP Publishing Ltd.


Xiao P.,London South Bank University | Xiao P.,Biox Systems Ltd | Ciortea I.,Biox Systems Ltd | Singh H.,London South Bank University | And 3 more authors.
Journal of Physics: Conference Series | Year: 2010

We have developed a new method for in-vivo human nail characterization by using opto-thermal transient emission radiometry (OTTER) and condenser-chamber TEWL (trans-dermal water loss) method - AquaFlux. With OTTER, we can measure nail water content, nail water concentration depth profiles, as well as topically applied solvent penetration through nail. With AquaFlux, we can measure nail transonychial water loss (TOWL). Combining the water content results with TOWL results, we can get the water diffusion coefficient of nail. Measuring the water diffusion coefficients of nail at different nail water concentration levels can also yield information on how nail diffusion coefficients change with water content. We will present the theoretical background, and experimental results on water concentration depth profile in nail, as well as topically applied solvent penetration through nail. © 2010 IOP Publishing Ltd.


Xiao P.,London South Bank University | Xiao P.,Biox Systems Ltd | Cui Y.,Sunrise Systems Ltd | Ciortea I.,Biox Systems Ltd | And 3 more authors.
Journal of Physics: Conference Series | Year: 2010

We present our latest study on the thermal diffusivity effect in opto-thermal skin measurements. We discuss how thermal diffusivity affects the shape of opto-thermal signal, and how to measure thermal diffusivity in opto-thermal measurements of arbitrary sample surfaces. We also present a mathematical model for a thermally gradient material, and its corresponding opto-thermal signal. Finally, we show some of our latest experimental results of this thermal diffusivity effect study. © 2010 IOP Publishing Ltd.


Xiao P.,London South Bank University | Xiao P.,Biox Systems Ltd. | Cui Y.,London South Bank University | Ciortea L.I.,Biox Systems Ltd. | And 2 more authors.
International Journal of Cosmetic Science | Year: 2012

We have developed a new method for studying human hair and nail water-holding capabilities by using the condenser-chamber trans-epidermal water loss (TEWL) method. Healthy hair and nail always contain certain amount of water, and they will lose this water to the environment naturally through evaporations. We monitored this desorption process by continuously measuring the water vapour flux density from hair and nail using the condenser-TEWL method, which is a condenser-based closed-chamber TEWL technology that is particularly suitable for this kind of measurements. We have also develop mathematical models for modelling the hair and nail desorption process. By fitting the normalized hair and nail desorption data with the mathematical models, we can get the water diffusion coefficient information, which can then be related to the water-holding capabilities of the hair and nail samples. © 2011 Society of Cosmetic Scientists and the Société Française de Cosmétologie.


Xiao P.,London South Bank University | Xiao P.,Biox Systems Ltd | Ou X.,London South Bank University | Ciortea L.I.,Biox Systems Ltd | And 2 more authors.
International Journal of Thermophysics | Year: 2012

This latest study on in vivo transdermal drug delivery by using opto-thermal radiometry and a capacitance-based fingerprint sensor is presented. A small amount of solvent was applied on the test sites of a volar forearm for a few minutes; opto-thermal measurements and fingerprint sensor measurements were performed both before the solvent application and periodically after. The results showed that, by selecting different detection wavelengths, opto-thermal radiometry could give the information either on the water concentration within skin or the solvent concentration within skin. The capacitance-based fingerprint sensor could clearly visualize solvent penetration through in vivo human skin, as it generated dynamic two-dimensional (2D) images of solvent distribution within skin, and combining with tape stripping, it was also possible to get solvent 3D depth profiles within skin. The correlation between opto-thermal transient emission radiometry and fingerprint sensor measurements was also evaluated. © 2012 Springer Science+Business Media New York.

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