"If we knew what it was we were doing, it would not be called research, would it?" - Albert Einstein

 

Our research focus is biodegradable nanocomposites. The group currently has three thrusts:

Controlled release systems

Remotely stimulated shape memory materials

Biomechanics

"If we knew what it was we were doing, it would not be called research, would it?" - Albert Einstein

Our research focus is biodegradable nanocomposites. The group currently has three thrusts:

Controlled release systems

Remotely stimulated shape memory materials

Biomechanics

CONTROLLED RELEASE FROM HALLOYSITE NANOTUBES

Chitosan-Covered Twice Drug-Loaded Halloysite - Zoomed Out 979 KX







D. dactyloides

Halloysite (HNT) is a clay nanotube, with an empirical formula of Al2Si2O5(OH)4. The structure of the individual tubes resembles a rolled stack of sheets. The outer and inner surfaces, consisting of hydroxyl groups, can be charged depending on the pH of the solution. The tubes are typically on the order of 1-2 microns in length and have an outer diameter that averages a few tens of nanometers. The hollow center of the tube is on the order of 25 nm in diameter. Drug adsorption on the inner or outer wall of the tube, and subsequent release, is a viable mechanism to develop controlled release systems. HNTs can be loaded with a variety of therapeutic agents and compounded with a range of polymers which can be processed into a range of wound dressing formulations including films, fabrics, and hydrogels. The ultimate goal of this thrust is to develop new controlled release wound dressing and packing systems to reduce infection rates in patients with diabetic foot ulcers and other chronic or difficult to treat wounds. In addition, we are evaluating halloysite as a novel controlled release system for herbicides, pesticides, and fertilizers.

 

REMOTE ACTIVATION OF SHAPE MEMORY POLYMERS

Shape memory polymers (SMP) are a type of smart material that responds to specific stimulus by recovering a previously set shape. Those that function in the range of body temperature have potential uses in novel medical devices and biological microelectro-mechanical systems (bio-MEMS). In the work being conducted in the lab we are utilizing the photothermal effect seen with anisotropic nanoparticles to convert light energy into thermal energy, locally heating the polymer and activating the shape memory behavior. The video demonstrates the remote heating of a polyurethane SMP by near infrared irradiation. The film on the right has been impregnated with a few ppm of gold nanorods while the film on the left has not. After only a few seconds of irradiation with the 808 nm light the film on the left shape recovers while the film on the left does not.

BIOMECHANICAL TESTING OF ORTHOPEADIC REPAIRS

TEMP cropped

Testing of orthopediac repairs can often involve the development of novel test protocols and testing apparatuses. For example, the figure shows the testing of repairs to proximal humerus fractures. The goal of the work, done in conjunction with Dr. Yaser El-Gazzar and Dr.Fred Flandry of The Hughston Foundation, was to evaluate the use of supplemental suture fixation on two and three part fractures. Of primary clinical importance is how the fixation limits gap growth at the repaired fracture during repetitive rotation of the humerus, the most common post-operative therapy. A custom biomechanical testing device that was capable of repeatedly rotating the humerus through a normal range of motion while simultaneously measuring gap size was designed and constructed in our lab. Testing was carried out on 12 matched cadaveric specimens. Suture fixation was found to be an effective method to limit gap formation for three part fractures but not for two part fractures. The figure shows gap formation after 200 cycles for specimens with repaired three part fractures. The specimen on the left had supplemental suturing while the specimen on the right did not.