Anuj Chauhan
Ph.D., 1998, City University of New York
Professor
Ph : 352-392-2592
chauhan@che.ufl.edu
261 ChESC
Areas
Tear film dynamics
Ophthalmic drug delivery
Contact Lenses
Drug detoxification
Microfluidics
Ophthalmic Drug Delivery

Keywords: Biomolecular/Biomedical, Materials/Devices, Nanosciences, Surface Science, Transport phenomena

We are developing better ophthalmic drug delivery vehicles. We have developed novel nanoparticle-laden soft contact lenses that deliver ophthalmic drugs for a period of about 5-6 days with significantly smaller drug loss to the systemic circulation. Animal trials of these lenses are planned and a product based on this technology is expected to be in the market in about 8 years. We are also interested modeling the process of nanoparticle encapsulation in the gels as well as the drug release from the particles, subsequent diffusion processes. Our work in this area has received much recent attention in the popular press including, CNN Headline News, and was listed in Reader's Digest Medical Breakthroughs 2004.
Ophthalmic Drug Delivery by Particle Laden Contact Lenses
Only about 1-5% of drugs delivered via eye drops reach cornea and the rest enters systemic circulations and causes side effects. We have developed transparent particle-laden contact lenses that deliver drugs at therapeutic doses for 5-30 days and that can lead to a 40 fold increase in the fraction of the entrapped drug that enters the cornea.
Image1 SEM image of microemulsion laden p-HEMA contact lens
Image2 Confocal Fluorescence Depth profiles for DMPC liposome laden p-HEMA contact lens
Image5 Schematic of a particle laden contact lens inserted in an eye
Inage3 Fluorescence image of microgel laden p-HEMA contact lens
Image4 Image6
 
Drug Release Profiles for a glaucoma drug (Timolol) from microgel-laden lenses (left) and nanostructured silicone hydrogels (top).
 
Ocular Transport and Physiology
Keywords: Biomolecular/Biomedical, Transport phenomena
Our group is combining mathematical modeling with In vitro experiments to develop an understanding of various physiological processes in the eyes and to understand factors that contribute to ‘dry eyes’, which is the most common ocular ailment, and also to develop possible treatments and efficient drug delivery vehicles. We have developed a model for tear dynamics that can predict the steady state tear film thickness, salt concentration and the electrical potential in the eye, and the dependency of these on physiological parameters such as tear secretion rates, salt concentration in the secreted tears, elastic properties of canaliculi, tear evaporation rates, etc. This model helps us understand various aspects of tear film dynamics and also helps us identify potential dry eye treatments. We are also studying a number of transport issues of relevance in ophthalmology. These include lipid spreading on the surface of the tear film, tear film breakup and transport of drug from the front surface of the eye to the retina. The eventual goal of our research efforts is to combine experiments and modeling to develop a comprehensive quantitative model for transport in the eye.
 
Drug Overdose Treatment
Keywords: Biomolecular/Biomedical, Materials/Devices, Nanosciences, Surface Science, Transport phenomena
Drug overdose is a major health care problem, as a number of widely used drugs can cause life-threatening toxicities and are without antidotes. Amitriptyline is one of the most widely prescribed tricyclic antidepressant in the United States, and it is also a common vehicle for suicide. Since no specific antidotes exist for this drug, the only method of overdose treatment is sequestration of the drug to reduce the free drug concentration. We are exploring the feasibility of using liposomes that can potentially sequester amitriptyline from blood for overdose treatment. We have developed various liposomal systems, both pegylated and unpegylated, that bind a significant amount of amitriptyline due to electrostatic interactions, and these reduce the free drug concentrations in human serum by more than 80%.
Image1
Schematic showing an IV injection of liposomes (green circles) into the circulatory system (top). The bottom schematic shows a magnified view of a tissue with liposomes flowing through the capillaries and adsorbing the flowing drug (purple circles) leading to reduction in free drug concentration.
Drug Overdose Treatment by Liposomes
About 300,000 patients visit emergency room each year due to drug toxicity. Currently, there are no antidotes to treat certain types of drug overdoses. We aim to develop liposomes that can be injected intravenously to sequester drugs and treat overdoses.
Image3
In human serum about 92% of the drug (amitriptyline) is bound to proteins (blue circles). Addition of DMPC:DOPG liposomes (pegylated, orange squares or unpegylated, triangles) increases the bound fraction to 96%-98% leading to at least 50% reduction in free concentration.
 
Other Research Initiatives
Keywords: Biomolecular/Biomedical, Complex Fluids, Soft Matter, Surface Science, Transport phenomena

Our group is also interested in the area of bioseparations, where we use microfluidic devices for DNA amplification and protein separation; in the area of interfacial and colloidal phenomena, where we focus on the transport of fluids across surfactanct-covered monolayers.

 
Recent Publications
1. Peng, CC, Burke MT, Carbia, BE, Plummer, C, Chauhan, A, “Extended Drug Delivery by Contact Lenses for Glaucoma Therapy”, Journal of Controlled Release, 2012, 162(1):152-15.
2. Peng, CC, Burke, MT, Chauhan, A, “Transport of Topical Anesthetics in Vitamin E Loaded Silicone Hydrogel Contact Lenses”, Langmuir, 2012 28(2):1478-87.
3 Jung, HJ, Chauhan, A, “Temperature Sensitive Contact Lenses For Triggered Ophthalmic Drug Delivery”, Biomaterials, 2012, Volume 33, Issue 7, Pages 2289–2300.
4. Peng, CC, McKay, E, Plummer, C, Chauhan, A, “Drug Delivery by Contact Lenses in Spontaneously Glaucomatous Dogs”, Current Eye Research, 2012, Vol. 37, No. 3 , Pages 204-211.
5. Gupta, C, Andrew, D, Chauhan, A, "Interaction of ionic surfactants with cornea-mimicking anionic liposomes", Langmuir, 2011, 27 (17), 10840–10846.