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Unusual Enthalpy Driven Self Assembly At Room Temperature With Chitosan Amphiphiles

Odunze, U; O'Brien, F; Godfrey, L; Schätzlein, A; Uchegbu, I; (2019) Unusual Enthalpy Driven Self Assembly At Room Temperature With Chitosan Amphiphiles. Pharmaceutical Nanotechnology , 7 (1) pp. 57-71. 10.2174/2211738507666190311123401. Green open access

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Abstract

HYPOTHESIS: GCPQ (N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan) is a self-assembling polymer being investigated as a pharmaceutical nano-carrier. GCPQ nanoparticles shuttle drugs across biological barriers, improving drug performance. The exact chemistry of GCPQ is varied by the relative proportion of hydrophobic (N-palmitoyl) and hydrophilic (quaternary ammonium) groups and molecular weight. We hypothesise that the thermodynamics of self-assembly is controlled by the polymer molecular weight and hydrophobicity. METHODS: The thermodynamics of self-assembly was investigated using isothermal calorimetry. FINDINGS: GCPQs (Mw = 8 - 15 kDa) formed micellar aggregates at critical micellar concentrations of 1 - 2.4 μM at 25 °C and micellisation was unusually enthalpy driven. There was a positive correlation between ΔHmic and Q: ΔHmic = 3.8 Q - 159 (r2 = 0.93) and a negative correlation between ΔHmic and molecular weight (Mw): ΔHmic = -13.5 Mw - 26.3 (r2 = 0.99). These findings provide insights into the positive drivers of stable self-assemblies, namely hydrophobicity and molecular weight, as both hydrophobicity and molecular weight are associated with an increased enthalpy contribution to micellisation.

Type: Article
Title: Unusual Enthalpy Driven Self Assembly At Room Temperature With Chitosan Amphiphiles
Location: United Arab Emirates
Open access status: An open access version is available from UCL Discovery
DOI: 10.2174/2211738507666190311123401
Publisher version: https://doi.org/10.2174/2211738507666190311123401
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Colloids, Critical Micelle Concentration (CMC), Endothermic, Enthalpy, Entropy, Exothermic, GCPQ, Micelle, Nanomedicine, Polymer, Thermodynamics
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > UCL School of Pharmacy
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > UCL School of Pharmacy > Pharmaceutics
URI: https://discovery.ucl.ac.uk/id/eprint/10070185
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