Solid lipid nanoparticles (SLN) based on pure triglycerides such as tripalmitate exhibit limited drug payloads and drug expulsion as a result of the high crystallinity of these particles. By using complex glycerides like hard fats as a matrix for SLN, the incorporation of lipophilic drugs is facilitated. However, these hard fat SLN reveal a tendency to form supercooled melts instead of solid particles. Even though these particles solidify at room temperature, they melt at body temperature. Therefore, these particles are not suited for controlled release applications. By mixing different solid lipids, e.g. trimyristin and tristearin, the crystal order is only slightly disturbed and thus no improvement in loading capacity can be expected. More promising appear to be mixtures of both, liquid (e.g. oils) and solid lipids (e.g. fats). To study the investigation of the mixing behavior of these liquid and solid lipids in the colloidal state, the characterization of the co-existence of additional colloidal structures is very important.
Fig. 1 Overview of lipid-drug conjugates. (Adhikari, 2017)
The differential scanning calorimetry (DSC) measurements allow the characterization of the crystallization process of the oil upon freezing. Information about the mobility, the arrangement, and the environment of the oil molecules are derived from 1H-NMR experiment. Linewidth is a parameter used to obtain information about lipid mobility and chemical shifts, which are related to the molecular environment. The mobility of the oil molecules is related to the width of the signal. Broad and weak signals are characteristic for molecules of restricted mobility. Decreased mobility of the molecules leads to a decrease in proton relaxation times, which results in considerable line broadening. For solid systems, such line broadening can usually lead to the absence of any detectable signal under the conditions used. Sharp and intense signals derive from molecules with high mobility. Information about the environment and arrangement of the molecules is related to the chemical shift of the signals. Signals at 0.9 ppm correspond to CH3 protons while those at 1.25 ppm derive from CH2 groups. The lower a CH2 group is located to electronegative groups, the more the peaks are displaced to higher ppm values.
Creative Biolabs is a professional mRNA services provider committed to moving mRNA-based therapeutics forward. Over years of practice, we have accumulated extensive experience in this field and gradually optimized our platform. Our platform is now capable of providing quality-guaranteed characterization services of lipid nanoparticle-formulated drugs. The co-existence of addition colloidal structures characterization is one of the projects we are good at. If you are working on mRNA-based therapeutics and need any assistance with colloidal structures characterization, please do not hesitate to contact us for more information.
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