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Screening for Optimal Liposome Preparation Conditions by Using Dual Centrifugation and Time-Resolved Fluorescence Measurements

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Institute of Pharmaceutical Sciences, University of Freiburg, 79104 Freiburg im Breisgau, Germany
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Signaling Research Centers BIOSS and CIBSS, University of Freiburg, 79085 Freiburg im Breisgau, Germany
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Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
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Andreas Hettich GmbH & Co. KG, 78523 Tuttlingen, Germany
*
Authors to whom correspondence should be addressed.
Academic Editor: Giovanna Della Porta
Pharmaceutics 2021, 13(12), 2046; https://doi.org/10.3390/pharmaceutics13122046
Received: 20 October 2021 / Revised: 19 November 2021 / Accepted: 25 November 2021 / Published: 30 November 2021
(This article belongs to the Section Pharmaceutical Technology, Manufacturing and Devices)
Dual centrifugation (DC) is a novel in-vial homogenization technique for the preparation of liposomes in small batch sizes under gentle and sterile conditions which allows encapsulation efficiencies (EE) for water soluble compounds of >50%. Since liposome size, size distribution (PDI), and EE depend on the lipid concentration used in the DC process, a screening method to find optimal lipid concentrations for a defined lipid composition was developed. Four lipid mixtures consisting of cholesterol, hydrogenated or non-hydrogenated egg PC, and/or PEG-DSPE were screened and suitable concentration ranges could be identified for optimal DC homogenization. In addition to the very fast and parallel liposome preparation of up to 40 samples, the screening process was further accelerated by the finding that DC generates homogeneously mixed liposomes from a macroscopic lipid mixture without the need to initially prepare a molecularly mixed lipid film from an organic solution of all components. This much simpler procedure even works for cholesterol containing lipid blends, which could be explained by a nano-milling of the cholesterol crystals during DC homogenization. Furthermore, EE determination was performed by time-resolved fluorescence measurements of calcein-loaded liposomes without removing the non-entrapped calcein. The new strategy allows the rapid characterization of a certain lipid composition for the preparation of liposomes within a working day. View Full-Text
Keywords: dual centrifugation; liposomes; vesicular phospholipid gel; encapsulation efficiency; time-resolved fluorescence; differential scanning calorimetry dual centrifugation; liposomes; vesicular phospholipid gel; encapsulation efficiency; time-resolved fluorescence; differential scanning calorimetry
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MDPI and ACS Style

Koehler, J.K.; Schnur, J.; Heerklotz, H.; Massing, U. Screening for Optimal Liposome Preparation Conditions by Using Dual Centrifugation and Time-Resolved Fluorescence Measurements. Pharmaceutics 2021, 13, 2046. https://doi.org/10.3390/pharmaceutics13122046

AMA Style

Koehler JK, Schnur J, Heerklotz H, Massing U. Screening for Optimal Liposome Preparation Conditions by Using Dual Centrifugation and Time-Resolved Fluorescence Measurements. Pharmaceutics. 2021; 13(12):2046. https://doi.org/10.3390/pharmaceutics13122046

Chicago/Turabian Style

Koehler, Jonas K., Johannes Schnur, Heiko Heerklotz, and Ulrich Massing. 2021. "Screening for Optimal Liposome Preparation Conditions by Using Dual Centrifugation and Time-Resolved Fluorescence Measurements" Pharmaceutics 13, no. 12: 2046. https://doi.org/10.3390/pharmaceutics13122046

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