Rachael Polowyj wins 2018 SCS Bursary

09/17/2018

 

Congratulations to Rachael Polowyj, winner of the 2018 SCS Bursary. This means Rachael will be taking her paper to this year’s IFSCC Congress in Munich (18-21 September 2018), with the SCS helping to fund her trip. Here Rachael explains her work and her reasons for applying:

The title for my paper is Exploring the effect of rheological modifiers and preservatives on the in vitro release of caffeine from gel formulations.

In a nutshell, I wanted to discover if changing the rheological modifier/thickener would affect the release of an active ingredient (caffeine) from the gel and through the skin. I made a range of 12 hydrogel formulations using five different chemical categories of rheological modifiers: cellulose derivatives (sodium carboxymethylcellulose, hydroxyethylcellulose); clays(hectorite, magnesium aluminium silicate); natural polymers (xanthan gum, carrageenan, gellan gum); polyacrylic acid polymers (carbomer, acrylates C10-30/alkyl acrylate crosspolymer, sodium polyacrylate) and silica-based thickeners (hydrated silica and silica). As all of the above rheological modifiers require different usage levels, I decided to control the viscosity by keeping each gel at 45 Pa.s +/- 20% at 20°C. Each hydrogel contained 2.000% of caffeine.

I tested the gels by dispensing a small amount onto an artificial skin membrane via a Franz cell experiment and measured the amount of caffeine that released through the gel and through the artificial skin. The results were quite interesting and showed that there were a variety of release patterns. Xanthan gum actually performed the worst with only 80% of the caffeine diffusing through the membrane. This showed me that xanthan gum can build a very strong gel network system, but this may prevent the active ingredient releasing out of the gel and into the skin.

I decided to test all the 12 hydrogels again but with the addition of 1% preservative (a blend of methyl and ethyl paraben in phenoxyethanol). In most cases, adding the preservative actually strengthened the gel structures with the exception of the sodium carboxymethylcellulose, hydrated silica and both the clays. In terms of release, similar effects were achieved and strangely with some cases, the addition of preservative sped up the release of the caffeine. This was not the case for the hydroxyethyl cellulose and all natural gums, whereby a lower release rate was detected after three hours, with the tendency to equalise later.

Interestingly, the expected pattern of decreased diffusion rate with an increase in viscosity was not consistently observed, with all polyacrylic acid and silica-based hydrogels being exceptions. In conclusion, this study has shown that both the rheological parameters (defined by the type of gelling agent) and the presence of preservative in the gel formulations affect the rate of release of a hydrophilic active caffeine.

Why did I apply?
I actually received an email from my teacher, Danka Tamburic, asking me if I wanted to submit my paper to the IFSCC. I was chuffed to bits because I had no idea that my paper was good enough to be considered and was flattered that my teacher thought so. My teacher helped me shorten my paper and submitted it on my behalf. I didn’t hear anything for a few months so I presumed I hadn’t been successful, then lo and behold I received an email from the IFSCC confirming that my abstract had been accepted for a poster presentation!! They confirmed that there were over 600 poster submissions, so this year was particularly difficult, which called for even more champagne!

After the bubbles and headaches had passed, I had a look online to work out an idea of costs. I was shocked that the congress was so expensive and as a graduate, there was no way I could afford to go. I remembered from university that some of my fellow students had been able to go via a bursary through the SCS, so I thought it was worth a shot. I contacted Gem Bektas and applied for the Tony Naylor Memorial Bursary Fund. Again, I wasn’t expecting to be successful and to my surprise I was awarded the bursary. Special thanks to the people who voted for me on the bursary committee of the SCS!

I am particularly excited to be attending the Congress alongside some of the top scientists in the world and to learn more about the great recent discoveries. It’s such a personal achievement for me and after the show has finished, I will celebrate in Munich how I know best – at Oktoberfest!!

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