Electron Spin Resonance

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Creative Biolabs has years of experience in offering innovative and sophisticated mRNA services based on our cutting-edge technologies and advanced platforms. We focus on the most widely used electron spin resonance techniques and their applications in the characterization of nanoparticles to meet your specific requirement.

Lipid nanoparticles (LNPs), including solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), represent a promising candidate for gene delivery. Lipid-based drug encapsulation systems comprise particles with a hydrophobic core stabilized by a superficial surfactant layer, with the active compound immersed in the lipid matrix. LNPs have several technical advantages, including (1) the use of biocompatible lipids, (2) high encapsulation, (3) control over release, (4) appropriate storage stability.

Electron Spin Resonance (ESR) for LNP Characterization

LNPs composed of solid and liquid lipids have surface properties that are key factors for their use. Electron spin resonance (ESR) spectroscopy has become a powerful and direct method to investigate dynamic phenomena and the nano-compartments in the colloidal lipid dispersions. ESR requires a paramagnetic spin probe to investigate LNP dispersions. The spin-label is simple gas dispersion and does not require elaborate isotope labeling as other hyperpolarization approaches. Direct, repeatable, and non-invasive characterization of the distribution of the spin probe between the aqueous and the lipid phase can be performed by ESR with exceptional sensitivity and specificity.

Monitoring of release mechanisms by ESR.Fig.1 Monitoring of release mechanisms by ESR. (Martini, 2009)

For LNP carrier systems loaded with spin-labels, it is known that ESR allows studying the individual surrounding of the rotational part of the spin-labelled spin molecule in terms of its rotational correlation time. Besides that, ESR can be used to study the distribution of spin-labelled analogues of fatty acids in SLNs. According to recent investigations of LNP carrier systems, the mode of drug-particle interaction appears to influence drug penetration. For a more detailed insight into the molecular structure of drug-loaded LNPs, the analytical method ESR has been applied for the discrimination between possible sites of the agent molecules, especially to answer the question of where inside the carrier matrix the agents are located. Besides the drug-carrier interaction, ESR imaging is also a valuable tool to study physicochemical properties of biological systems, drug distribution in multiphase systems and processes taking place at phase boundaries, including skin penetration.

Creative Biolabs has made a long-term commitment to mRNA delivery. To bring our customers impeccable service, our seasoned scientific team has developed an integrated ESR platform with LNPs characterization. To learn more about our solutions, please do not hesitate to contact us for more details.


  1. Martini, G.; Ciani, L. Electron spin resonance spectroscopy in drug delivery. Physical Chemistry Chemical Physics. 2009, 11(2), 211-254.
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