Colloids and Crystal Engineering Laboratory
Indian Institute of Technology Gandhinagar
Engineering microbubbles for biomedical applications
Microbubbles are colloidal particles with 0.1 to 10 μm diameter and consist of a shell made of lipid or protein molecules. The shell encapsulates a gaseous core containing gases such as Perfluorobutane (PFB), Sulphur Hexafluoride (SF6) or Oxygen (O2). The microbubble shell can contract and expand upon exposure to ultrasound. This phenomenon enables the use of microbubbles in applications such as contrast imaging, sonoporation and as drug/gene delivery vehicles. Our research efforts are focused on synthesis of microbubbles and understanding the effect of shell material, additives, storage medium and transport properties of core gas on the stability and biocompatibility of aqueous microbubble suspensions.
Cocrystallization to enhance aqueous solubility of poorly water soluble drugs
Cocrystallization is a crystal engineering approach where a multicomponent pharmaceutical solid phase can be engineered using water soluble coformers to enhance dissolution rates and thereby improve bioavailability of poorly water soluble drugs. Cocrystallization of active pharmaceutical ingredient (API) with water soluble coformers does not always result in cocrystals but can also lead to formation of eutectics, coamorphous solids or even physical mixtures. Our research focuses on understanding the rationale behind formation of different solid phases such as cocrystals, eutectics, amorphous solids and physical mixtures during cocrystallization by developing insight to the intermolecular interactions among the drug and coformer molecules.
Drug Polymorphism
Polymorphism is defined as the ability of a compound to exist in different solid crystalline phases, which have different arrangements and/or conformations of molecules in solid state. Studies related to the polymorphism are highly important for drug development as different polymorphs have different physicochemical properties and different solubilities. It is therefore neccessary to gain control over the formation of polymorphs during precipitation/crystallization and prevent polymorphic transformations during storage. We are trying to identify the thermodynamic and kinetic factors that significantly affect the polymorphism which can help in facilitating formation of desired polymorphs during crystallization.
Antisolvent crystallization of poorly water soluble drugs
Liquid antisolvent (LAS) precipitation is an alternative to several energy intensive top-down and bottom-up techniques which are currently being used to produce ultrafine particles of poorly water soluble drugs. LAS enables rapid precipitation of solute from solution by addition of another solvent (antisolvent) in which solute is insoluble. The mixing of antisolvent with solvent generates rapid supersaturation by lowering the solubility of the solute in the solution. The generation of a rapid supersaturation favors nucleation over growth leading to formation of submicron particles. We use a combination of ultrasound and polymeric additives to control particle size and size distribution during (LAS) precipitation by way of manipulating supersaturation, nucleation kinetics and particle growth.
Liquid Marbles
Liquid droplets encapsulated in a layer of hydrophobic particles are called as Liquid Marbles (LM). The hydrophobic shell provides a protective cover making the LM selectively permeable to gases and restrict contact of solid or liquid with the liquid inside the hydrophobic shell. LMs can be used as effective microreactors for biological/chemical processes and as gas sensors due to their selective permeability to gases. LMs can be synthesized by rolling or shaking of droplets on a hydrophobic powder bed, by mixing of liquid and particles in an optimal liquid to particle ratio or by releasing liquid droplets on a hydrophobic powder bed from a certain height. We are trying to understand the dynamics of LM formation during its impact on the bed of hydrophobic particles and estimate the effect of various process parameters such as viscosity, surface tension, and the nature of particles on LM formation.
