Saturday, June 25, 2016

Nanostraw microdevices fabricated using ALD to deliver drugs


 (From Nanotechweb) Researchers in California have designed microdevices that can adhere to the lining of the gastrointestinal (GI) tract and release therapeutic drugs slowly. The devices are sealed with nanostraws that also protect the loaded drug from enzymes in the GI.

 
(A) SEM images show that microdevices have intact nanostraw membranes. (B) Confocal fluorescence microscopy of nanostraw devices. Courtesy: ACS Nano : ACS Nano DOI: 10.1021/acsnano.6b00809

Increasing drug uptake

The researchers made their nanostraw membranes using track etch and atomic layer deposition. They then incorporated the membranes into the microdevices using polymer deposition, photolithography and reactive ion etching steps.

“We load drugs into the device reservoirs by diffusion,” explains team member Cade Fox. “The devices could then be administered orally, and we would expect them to adhere to the lining of the GI tract and release drug towards GI tissue at high concentrations for prolonged durations, thereby increasing drug uptake.” 



Fabrication of Sealed Nanostraw Microdevices for Oral Drug Delivery

Cade B. Fox, Yuhong Cao, Cameron L. Nemeth, Hariharasudhan D. Chirra, Rachel W. Chevalier, Alexander M. Xu, Nicholas A. Melosh, and Tejal A. Desai
 
ACS Nano, Article ASAP
 
The oral route is preferred for systemic drug administration and provides direct access to diseased tissue of the gastrointestinal (GI) tract. However, many drugs have poor absorption upon oral administration due to damaging enzymatic and pH conditions, mucus and cellular permeation barriers, and limited time for drug dissolution. To overcome these limitations and enhance oral drug absorption, micron-scale devices with planar, asymmetric geometries, termed microdevices, have been designed to adhere to the lining of the GI tract and release drug at high concentrations directly toward GI epithelium. Here we seal microdevices with nanostraw membranes—porous nanostructured biomolecule delivery substrates—to enhance the properties of these devices. We demonstrate that the nanostraws facilitate facile drug loading and tunable drug release, limit the influx of external molecules into the sealed drug reservoir, and increase the adhesion of devices to epithelial tissue. These findings highlight the potential of nanostraw microdevices to enhance the oral absorption of a wide range of therapeutics by binding to the lining of the GI tract, providing prolonged and proximal drug release, and reducing the exposure of their payload to drug-degrading biomolecules.