Presentation Information
[P04-521]Physicochemical Mapping of pH-Responsive Ternary Lipid Vesicles via In-line Microfluidic HTS Platform
○Harutomo Aiba1, Junghu Lee1, Dabin Lim1, Nozomi Watanabe Morishita1, Noriko Yoshimoto2, Seonghyeon Eom3, Moonkyu Kwak4, Hosup Jung3,5, Hiroshi Umakoshi1 (1. The University of Osaka (Japan), 2. Yamaguchi University (Japan), 3. Nbiocell Inc. (Korea), 4. Kyungpook National University (Korea), 5. Seoul National University (Korea))
Keywords:
liposome,microfluidics,membrane properties,high-throughput system,pH-response liposome
[Purpose]
Liposomes are utilized as nanocarriers in drug delivery systems. Stimuli-responsive liposomes have been developed to trigger cargo release at target, such as acidic tumor microenvironments and endosomal compartments (pH 5.0–6.5). Designing such systems requires understanding how lipid composition modulates membrane physicochemical properties across different pH. Manual methods, such as thin-film hydration, are labor-intensive and low-throughput, limiting systematic investigation of the broad lipid compositional space. We developed a microfluidic high-throughput screening (HTS) platform for the continuous, in-situ profiling of pH-responsive lipid membranes (POPC/DOPE/Cholesterol). Integrating a gradient mixer with in-line spectroscopy enables the generation of high-density physicochemical datasets.
[Method]
The system comprises a low-pressure gradient mixer (HPLC pump PU-4180), microfluidic mixer, and an in-line fluorometer . In-line dilution (pump PU-980, 4.8 mL/min PBS) achieved a 1:6 dilution. 5 mM lipid ethanol solutions were mixed with 10 mM PBS (pH 7.4 or pH 5.0) at flow rate ratio of 7 and a total flow rate of 0.8 mL/min. Membrane properties were monitored via interfacial polarity (GP340, surface hydration) and core rigidity (rDPH, acyl chains anisotropy) every 5-15 s .
[Results]
High-resolution physicochemical maps were successfully generated . The key findings are as follows: (i) at pH 7.4, both GP340 and rDPH increased with increasing DOPE and cholesterol content, reflecting enhanced membrane packing; (ii) at pH 5.0, DOPE-rich formulations exhibited significant GP340 increases, suggesting that DOPE protonation promotes a transition to an ordered state or an inverse hexagonal phase (HII), leading to interfacial tightening ; and (iii) increased cholesterol content enhanced membrane rigidity and mitigated pH-induced perturbations in the hydrophobic core, highlighting its stabilizing role in stimuli-responsive nanocarriers.
[Consideration]
The in-line HTS framework addresses manual characterization challenges, specifically their labor intensity and low throughput.
[Conclusion]
The HTS platform enabled the visualization of dynamic, pH-triggered transformations in the POPC/DOPE/Chol system. These physicochemical fingerprints offer insights into stimuli-responsive lipid membranes and aid in the rational design of nanocarriers.
Liposomes are utilized as nanocarriers in drug delivery systems. Stimuli-responsive liposomes have been developed to trigger cargo release at target, such as acidic tumor microenvironments and endosomal compartments (pH 5.0–6.5). Designing such systems requires understanding how lipid composition modulates membrane physicochemical properties across different pH. Manual methods, such as thin-film hydration, are labor-intensive and low-throughput, limiting systematic investigation of the broad lipid compositional space. We developed a microfluidic high-throughput screening (HTS) platform for the continuous, in-situ profiling of pH-responsive lipid membranes (POPC/DOPE/Cholesterol). Integrating a gradient mixer with in-line spectroscopy enables the generation of high-density physicochemical datasets.
[Method]
The system comprises a low-pressure gradient mixer (HPLC pump PU-4180), microfluidic mixer, and an in-line fluorometer . In-line dilution (pump PU-980, 4.8 mL/min PBS) achieved a 1:6 dilution. 5 mM lipid ethanol solutions were mixed with 10 mM PBS (pH 7.4 or pH 5.0) at flow rate ratio of 7 and a total flow rate of 0.8 mL/min. Membrane properties were monitored via interfacial polarity (GP340, surface hydration) and core rigidity (rDPH, acyl chains anisotropy) every 5-15 s .
[Results]
High-resolution physicochemical maps were successfully generated . The key findings are as follows: (i) at pH 7.4, both GP340 and rDPH increased with increasing DOPE and cholesterol content, reflecting enhanced membrane packing; (ii) at pH 5.0, DOPE-rich formulations exhibited significant GP340 increases, suggesting that DOPE protonation promotes a transition to an ordered state or an inverse hexagonal phase (HII), leading to interfacial tightening ; and (iii) increased cholesterol content enhanced membrane rigidity and mitigated pH-induced perturbations in the hydrophobic core, highlighting its stabilizing role in stimuli-responsive nanocarriers.
[Consideration]
The in-line HTS framework addresses manual characterization challenges, specifically their labor intensity and low throughput.
[Conclusion]
The HTS platform enabled the visualization of dynamic, pH-triggered transformations in the POPC/DOPE/Chol system. These physicochemical fingerprints offer insights into stimuli-responsive lipid membranes and aid in the rational design of nanocarriers.
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