Surfactant therapy in

Respiratory Distress Syndrome (RDS)

u Respiratory Distress Syndrome affects 2/3rd of all preterm infants

u Cause: Quantitative or functional deficiency in lung surfactant

u Modes of therapy:

l Mechanical ventilation

l Supplemental oxygen

l Surfactant replacement - Physiologic

u Role of surfactant:

l Reduction of surface tension at air-alveolar interface

l Prevention of alveolar collapse

l In accordance with Laplace law: D P =

 

 

Findings & Conclusions

u Pulsating bubble surfactometer relevant to lung alveolar system

u Frequency dependant response of surfactants:

l PCPG best at 20 cpm

l PG best at higher frequencies (40 & 60 cpm)

u Monolayer studies by L-B trough

l PCPG better than commercial surfactants

u Morphological studies by Cryogenic SEM

l Presence of tubular myelin with addition of calcium (5mM)

l PCPE & PCPG form larger liposomes

u New, superior formulations with adjuvants developed for RDS.

(Patents in pipeline.)

 

 

 

Pulsating Bubble Surfactometer (Schematic)

 

 

 

Ultramicroscopy techniques for

soft solids and complex liquids

Soft solid and complex liquids are ubiquitous in chemical engineering. Research into their structure needs specialized techniques for investigations because samples are neither a solid nor a liquid but something in between. Persistent efforts have gone on in developing in Cryo SEM techniques with freeze-fracture facility at the Chemical Engineering Dept. This technique which involves viewing microstructures of wet samples, with a resolution of 1 micron, maintaining the vacuums used in conventional SEM. The various steps involved are

  1. Fast freezing of the wet samples, with cooling rates of 104 K/Sec, to preserve the microstructures.
  2. Transferring the samples in to the body of SEM – while maintaining the cold-chain, and without breaking the vacuum or changing the microstructure of the samples.
  3. Fracturing the sample in vacuum to view the internal microstructure.

This expertise has been developed over the years in the Chemical Engineering Department and the possibly the only laboratory in India where such a facility exists. Some of the samples which have been investigated are

  1. Liposomes which are normally used for encapsulation and drug delivery systems
  2. Other surfactant microstructures useful as microreactors for preparation of nanoparticles.
  3. Hair samples for evaluation for shampoos.
  4. Ice-cream and other processed foods and spices
  5. Study of new soap bars based on microstructuring

 

Myelins: Structure, coiling and ordered nanoparticles

Surfactants are important component in many biological and industrial systems as well as in various consumer products. Surfactants form a variety of microstructures in solution, some of which are equilibrium and others non-equilibrium microstructures. All such microstructures are surfactant aggregates, also known as "association colloids". During the dissolution of a surfactant in the solvent, various types of non-equilibrium microstructures have been observed. The most interesting and fascinating non-equilibrium microstructure is the "myelin figure" that forms by a dynamic processs called "myelin growth".

SMyelins are highly viscous, gel-like, microstructures consisting of multilamellar tubules of alternating amphiphile bilayer and water layer with a core axis of water (fig 1). The structural features of myelin figure is essentially similar to that of the nerve myelin sheath, the white matter insulating the nerves, which allows the conduction of impulses from one part of the body to the other. Thus the bilayers of myelins have structural resemblance with biomembranes.

Fig.1 : Schematic representation of a Myelin

(from http:// markun.cs.shinshu-u.ac.jp/artscape/artsc/reci/myeline.html ).

This phenomena is a manifestation of dynamic interface instability involving rearrangement of the bilayers of the surfactant lamellar phase (La ). It is a sort of bilayer reorganisation involving swelling of the surfactant lamellar phase.

We have used our microstructure expertise to probe the strucutre and coiling of such myelins, and to use them as reactors to produce nanoparticles. The most dramatic finding is the helical structures and ordering of nanoparticles.

 

 

 

Myelin Growth in AOT/water system

(a) (b) (c)

Coiling in AOT/ 5 wt% aqueous PTS solution system

 

 

Formation & ordering of CaCO3 nanoparticles on myelin structures

 

 

 

 

 

 

 

Special Materials: COMPOSITE POLYANILINE-STAINLESS STEEL MEMBRANE for gas separation

u Composite membranes of polyaniline S.S. prepared by electrochemical polymerization

u Microstructural studies of the formation of the polymer in the tortuous pores of the SS substrate done. Graded growth seen.

u The bulk of the polymer was formed on the surface and within 200m m from the surface of the substrate.

u Electrochemically doping with various ions show a.

l Decrease in the fibrillar size of the polymer

l Permeablity can be changed sevreal fold

l Tuneablity of selectivity: nanoengineering

Microstructure of the composite membrane.

 

Integrated plant for Biomedical Optics

Technology developed and transferred:

u Design and development of vertically integrated pilot plant for optical glass fibers

u Technology for conversion into light guide and image guide applications developed.

u Micro-optic devices like endoscopes developed.

u Other end-products and accessories like illunimators developed and commercialised

u Plant was extended to include a microcapillary drawing system. One thousand meters was drawn with ±10m m tolerance.

 

 

 

Continuous pressing plant for microfiltration membrane production

u Lab-scale, pilot-scale, and commercial scale plants were scaled-up and commissioned for production of cellulosic membrane filters for microfiltration of pharamaceuticals and use in biomedical devices.

u Down-stream conversion plant into finished products like blood filters and syringe adapters was developed.

u Test marketing is complete with excellent results and feedback from leading research labs and pharmaceutical companies.