title: Study on the Unfrozen Water Quantity of Maximally Freeze-Concentrated Solutions for Multicomponent Lyoprotectants.
abstract: The concentration of maximally freeze-concentrated solutions [Formula: see text] and the corresponding glass transition temperature [Formula: see text] and ante-melting temperature [Formula: see text] of lyoprotectant solutions, are critical parameters for developing lyophilization process. Usually, the lyoprotectant solutions are multicomponent solutions composed of electrolytes, sugars, proteins, polymers, and other chemicals. In this article, the Wg'values of several multicomponent solutions including trehalose/NaCl, bovine serum albumin/NaCl, and hydroxyethyl starch/NaCl with water were determined by differential scanning calorimetry. A linear relationship between the unfrozen water fraction Wunand the initial solute concentrations Wiwas found: Wun= ∑(ai·Wi), which suggested that in the multicomponent solutions each solute could hydrate a certain amount of water ai(g water/g solute) that could not be frozen. The hypothesis was compared with more literature data. For the same solute in different solutions, variation in the fitted coefficient aiis noticed and discussed. If a "universal" value aifor each solute is adopted, both [Formula: see text] and [Formula: see text] for a multicomponent solution could be predicted if Couchman-Karasz equation is adopted for calculating glass transition temperature at the same time. The prediction discrepancies for [Formula: see text] with experimental data were less than 2°C. The finding is discussed about its molecular basis and applicability.
authors.affiliation: Institute of Refrigeration and Cryogenics, Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Zhejiang University, Hangzhou 310027, China.
authors.forename: Mengjie
authors.initials: M
authors.lastname: Xu
authors.affiliation: Institute of Refrigeration and Cryogenics, Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Zhejiang University, Hangzhou 310027, China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Chen
authors.affiliation: Intensive Care Center, People's Liberation Army No. 117 Hospital, Hangzhou 310013, China.
authors.forename: Cunhai
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Institute of Refrigeration and Cryogenics, Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Zhejiang University, Hangzhou 310027, China. Electronic address: enezsz@zju.edu.cn.
authors.forename: Shaozhi
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D002417:Cattle; D005612:Freeze Drying / Q000379:methods; D005615:Freezing; D006895:Hydroxyethyl Starch Derivatives / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D044366:Transition Temperature; D014199:Trehalose / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D006895:Hydroxyethyl Starch Derivatives; D014867:Water; D012710:Serum Albumin, Bovine; D012965:Sodium Chloride; D014199:Trehalose
keywords: glass transition; lyoprotectants; maximally freeze-concentrated solution; unfrozen water