Systematic of alcohol-induced simple coacervation in aqueous gelatin solutions. 2003

B Mohanty, and H B Bohidar
School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110016, India.

Turbidity measurements performed at 450 nm were used to follow the process of simple coacervation when 1% (w/v) aqueous alkali processed gelatin (type-B) solutions were titrated with methanol, ethanol, propanol, and tert-butyl alcohol at various pHs of the solution ranging from pH = 5 to 8 and ionic strengths varying from I = 0.01 to 0.1 M NaCl. The titration profiles clearly established the transition points in terms of the percentage of volume of alcohol added relative to that of solvent corresponding to the first occurrence of turbidity (Vt) and a point of turbidity maximum (Vp). Addition of more alcohol drove the system toward precipitation. The values of Vt and Vp characterized the initiation of intramolecular folding and intermolecular aggregate formation of the charge neutralized gelatin molecules and the subsequent micro coacervate droplet formation. The state of intermolecular aggregates and that of folded gelatin molecules could be characterized by dynamic laser light scattering experiments, which implied spontaneous segregation of particle sizes preceding coacervation. The aggregates constitute the coacervate phase while the folded gelatin molecules mostly stay dispersed in the supernatant. The data taken together reveal the role played by solution entropy in addition to that of electrostatic and solute-solvent interactions, which had been overlooked hitherto.

UI MeSH Term Description Entries
D009994 Osmolar Concentration The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent. Ionic Strength,Osmolality,Osmolarity,Concentration, Osmolar,Concentrations, Osmolar,Ionic Strengths,Osmolalities,Osmolar Concentrations,Osmolarities,Strength, Ionic,Strengths, Ionic
D005780 Gelatin A product formed from skin, white connective tissue, or bone COLLAGEN. It is used as a protein food adjuvant, plasma substitute, hemostatic, suspending agent in pharmaceutical preparations, and in the manufacturing of capsules and suppositories. Gelafusal
D006863 Hydrogen-Ion Concentration The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000438 Alcohols Alkyl compounds containing a hydroxyl group. They are classified according to relation of the carbon atom: primary alcohols, R-CH2OH; secondary alcohols, R2-CHOH; tertiary alcohols, R3-COH. (From Grant & Hackh's Chemical Dictionary, 5th ed)
D012996 Solutions The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed) Solution
D013696 Temperature The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms. Temperatures
D014867 Water A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Hydrogen Oxide

Related Publications

B Mohanty, and H B Bohidar
August 2006, The Journal of chemical physics,
B Mohanty, and H B Bohidar
November 2012, The journal of physical chemistry. B,
B Mohanty, and H B Bohidar
January 1985, Journal of microencapsulation,
B Mohanty, and H B Bohidar
February 1983, The Journal of pharmacy and pharmacology,
B Mohanty, and H B Bohidar
January 1985, Journal of microencapsulation,
B Mohanty, and H B Bohidar
February 1992, Physical review. A, Atomic, molecular, and optical physics,
B Mohanty, and H B Bohidar
January 2004, Water research,
B Mohanty, and H B Bohidar
February 2013, Langmuir : the ACS journal of surfaces and colloids,
Copied contents to your clipboard!