Scientists in Asia and in the US have reported progress on the development of microneedles as a painless means of injecting drugs or taking blood samples.
In Asia Suman Chakraborty of the Indian Institute of Technology in Kharagpur and Kazuyoshi Tsuchiya of Tokai University in Kanagawa have developed a painless microneedle for blod sampling which is claimed to mimic the way a female mosquito sucks blood when it bites.
These microneedles are fabricated by employing the sputtering deposition method and result in a needle with an inner diameter of around 25 µm and an external diameter of 60 µm - about the same size as a mosquito's mouthpart - compared with a conventional syringe needle, which has an outer diameter of around 900 µm.
The needle, made of titanium and related alloys, is also strong enough to penetrate as far as 3 mm into skin and reach capillary blood vessels.
In a report1 published in the Journal of Applied Physics the researchers claim to have achieved good experimental results.
Meanwhile, in what is believed to be the first peer-reviewed study of its kind involving human subjects, researchers at the University of Kentucky and the Georgia Institute of Technology have demonstrated that patches coated on one side with microscopic stainless steel needles can facilitate transdermal delivery of clinically-relevant doses of a drug that normally cannot pass through the skin.
Reported in the journal Proceedings of the National Academy of Sciences2, the study could help advance the use of microneedles as a painless method for delivering drugs, proteins, DNA and vaccines into the body.
The research also found other advantages for the microneedles, including an ability to produce therapeutic drug levels with lower doses, and lowered production of metabolites that may cause side-effects.
The study represents a first step in demonstrating the broad range of potential uses for microneedles, said Mark Prausnitz, a professor in the Georgia Tech School of Chemical and Biomolecular Engineering, who has been developing the devices for more than 10 years. In addition to Prausnitz, the Georgia Tech research team also included Harvinder Gill and Jyoti Gupta.