Silk microneedles are claimed to better-deliver medication


December 22, 2011

Scientists have created microneedles made from silk, which are said to offer several advantages over traditional microneedles

Scientists have created microneedles made from silk, which are said to offer several advantages over traditional microneedles

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Microneedles continue to show promise as a replacement - in at least some applications - for the hypodermic needle. Typically, a sheet containing an array of the tiny needles is adhered to the patient's skin, like a bandage. The microneedles painlessly pierce the top layer of skin, then gradually deliver the medication within them by harmlessly dissolving into the patient's bloodstream. As an added bonus, once everything is complete, there are no bio-hazardous used needles to dispose of. Now, bioengineers from Massachusetts' Tufts University have developed what they claim is an even better type of microneedle, which is made from silk.

With some types of existing microneedles, the harsh conditions required for their production can destroy the sensitive biochemicals that they were supposed to deliver. It can also be difficult to fine-tune the rate at which they deliver their medication, plus infections can sometimes occur where they enter the skin. According to the Tufts scientists, their silk microneedles address all of these problems.

The team started with aluminum molding masters that contained arrays of microneedles, each needle measuring 500 micrometers in height, with tips less than 10 micrometers in diameter. An elastomer was cast over those masters to create a negative mold, then a drug-laden silk protein was cast over that mold. Once the silk was dry, it was removed from the mold, then further processed using water vapor and various other means.

The whole procedure was conducted under ambient pressure and temperature, and resulted in biocompatible, dissolving silk microneedles impregnated with the large-molecule drug, horseradish peroxidase.

Using methods such as varying the silk protein's drying time, the researchers were able to alter its structure, which in turn allowed them to precisely control its rate of drug release. It was also found that adding tetracycline to the protein inhibited the growth of Staphylococcus aureus bacteria at the application site on the skin.

As with other types of microneedles, the silk needles can be shipped and stored without refrigeration.

The Tufts research was detailed in a paper, which was published this month in the journal Advanced Functional Materials.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

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Dave Flanagan, Advanced Functional Materials

Dave Flanagan

If they are made with aluminum does that mean that they have residual aluminum on them when they inject the patient? We want to avoid injecting aluminum into the human body don\'t we?

Carlos Grados

Hopefully can implement this new tech in msia... Needle stick injury rate can b reduce n less bio-hazard risk to those health care giver...

Summer Rosy

I am a Chinese student in Korea University now. I have invented the silk microneedles and published my previous results in an IEEE conference in 2010 and MSE. In my previous experiments, I also found that I can program the MNs properties during the drying and post-processing. But I found that the silk MNs\' degradation rate and mechanical hardness is a trade-off relationship. If I want to make the MNs harder, I need to sacrifice the MNs\' degradation rate. The slow degradation could make the patient feel uncomfortable. I donot want the MNs stay in my body for too long time. So I repeat the experiments until I get strong and rapidly dissolvable MNs. I propose an idea that by mixing the protein solution with some easily dissoluble moleculars during the dring may accelerate the dissolving rate in my previous paper. As I am a foreign student in Korea, I was limited for further researches about the MNs drug testing. I hope we could have some collaboration to develop some idea biomedical devices for the puclic health care.

My email:

If you want to learn more bout my previous research, you can read more in the papers.

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