Skin modeling and optical characterization using visible light

Announcement : ISE Senior Project Yr2010
Skin penetration modeling and optical characterization using visible light.

The aim of the projects is to study, analyze and characterize the change of the density of the
epidermis layer from visible light reflection. The desired outcome is to be able to extract the
density of an adsorbed solution in the epidermis/dermis layers.
Background
A proposed scheme for the project is illustrated in Figure 1. Figure 1. illustration of the desired apparatus and results. The project can be divided into three sub-projects: modeling, optical setup and biomedical sample preparation (Penetration of XX through skin layers). Each one of these can be treated as an individual senior project with one or two students involved. 1.1. Modeling of the effect of density change of epidermis on the reflection

In this part the existing Monte-Carlo simulations will be used to study the effect of the change
of density on reflection. That includes testing for the suitable wavelength of use and
interpreting the density from the reflection calculations. A second phase of this part would be
using the ASAP software from BRO to bench-mark the results from the Monte-Carlo code.
1.2.Optical apparatus

This part deals with building an optical fiber-optics based measurement apparatus. The setup
should allow for the use of a multimode optical fiber to launch mono-chromatic light through
the tissue and collect the back reflection. The setup should allow for scanning at least in one
direction. The second phase would be allowing for two-dimensional scan. A possible setup is
depicted in figure two.
In the setup, the 2x2 coupler splits the input source into two signals each carries 50% of the originally coupled source light into the input fiber (tagged 1). One arm (tagged 3) is detected and recorded as a reference. The second arm (tagged 4) launches the light into the skin and collects it back. The reflected light is split again in the coupler and half of it is recorder in detector 2. A set of data is recorder when scanning across the skin sample and the data are interpreted to extract the density information. Detector (1)
Detector (2)
2x2 coupler
1.3. Sample preparations and evaluation of drug (Diclofenac) penetration through skin
This part deals with sample preparation including literature searches for properties and analysis of drug selected for skin delivery test. A skin chamber will be constructed similar to the apparatus in the “Franz’s diffusion cell” to be used in experiment 1.2 and 1.3. Diclofenac, a non-steroidal anti-inflammatory drug (NSAID), will be used as a model for skin penetration specie. Saturated drug will be applied on fresh porcine skin from young piglets. The skin sample will be harvested at each time period (30 min., 1 and 3 hrs.). Amount of drug in each skin layer (epidermis, by tape stripping method, and dermis, by mincing the tissue) will be analyzed using Spectrophotometry. Data obtained from this experiment will be compared to the literatures and to the results in experiment 1.1 and 1.2. (Porcine
A 37C)
2. Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) taken to reduce
inflammation and as an analgesic reducing pain in conditions such as arthritis or acute injury. It can also be used to reduce menstrual pain, dysmenorrhea. The name is derived from its chemical name: 2-(2,6-dichloranilino) phenylacetic acid. IUPAC name 2-[2-[(2,6-dichlorophenyl)amino]phenyl]acetic acid

Formula C14H11Cl2NO2 Mol. mass 296.148 g/mol
Protein binding: more than 99%
Metabolism: hepatic, no active metabolites exist
Half-life: 1.2-2 hr (35% of the drug enters enterohepatic recirculation)
Excretion: biliary, only 1% in urine

Spectrophotometric determination of diclofenac sodium in tablets
Y. K. Agrawala, and K. Shivramchandrab
Journal of Pharmaceutical and Biomedical Analysis
Volume 9, Issue 2, 1991, Pages 97-100

Abstract
Simple spectrophotometric methods are described for the determination of diclofenac. In the
first method diclofenac reduces iron(III) to iron(II) when heated in aqueous solution. The
ferrous ions produced react with 2,2′-bipyridine to form a complex having a maximum
absorbance at 520 nm. The reaction obeys Beer's Law for concentrations of 10–80 μg ml−1.
This method can be applied to the determination of diclofenac in tablets. In the second
method, diclofenac is treated with Methylene Blue in the presence of phosphate buffer (pH
6.8) and the complex is extracted with chloroform. The complex has a maximum absorbance
at 640 nm and the graph of absorbance against concentration is linear in the range 5–40 μg
ml−1. This method can be applied to the determination of diclofenac in tablets that also
contain paracetamol.

3. Senior projects

Two projects are proposed. Each project needs 3 students, as follows:
Project 1: Modeling of drug concentration in skin vs. light reflection and Optical
apparatus setup: advisors: Dr.Siriporn and Dr.Waleed (for ICE or NANO students who
have background on modeling or wish to develop your modeling skill)
More details pls contact Dr.Waleed or cell phone
Project 2: Evaluation of drug penetration through skin layers: advisors: Dr.Sorada and
Dr.Pornanong (for NANO students)
More details pls contact Dr.Sorada (@Chem Eng , tel.02-2186867)

Source: http://www.ise.eng.chula.ac.th/ise/images/stories/web/Information%20of%20Topic%201skin%20projects%20Dr.sorada.pdf