In the last decade, liquid-phase electron microscopy (LPEM) has
provided a new strategy for investigating samples immersed in
their media at the nanoscale.1–8 The main focus of previous
research have mainly revolved around inorganic matter (e.g.
metallic nanoparticles);9 nonetheless, the field of soft materials,
classified as organic synthetic (i.e. polymers and gels), and
biological (i.e. membranes and protein) structures have rapidly
grown interest in LPEM to study fundamental questions.2 Soft
materials deform easily or undergo dynamic changes by thermal
fluctuations and external forces. Despite the great advantages
LPEM provides, electron beam damage and image contrast
present still an issue, particularly in sensitive samples. New technological and methodological advances may attenuate
these issues. There is a need to employ these advancements to
develop strategies to image soft materials. This thesis focuses
on the development of methodologies for the investigation of soft
materials using LPEM. Amongst the different conducted studies,
there are three main sections of focus: (i) the reconstruction of
three-dimensional (3D) structures via Brownian tomography
(BT) and Brownian particle analysis (BPA), enabling the investigation of the 3D conformational space of single unit of the
specimen, via BT, and an average reconstruction of several
specimens, via BPA; (ii) the dynamic studies of biological and
synthetic soft materials, specifically oxidant-sensitive polymeric
micelles and viruses, focusing on their disassembly via external
factors, reactive-oxygen species (ROS) and virucidal
nanoparticles respectively; and (iii) the imaging of intracellular
ultrastructure via organometallic, cyclometalated complexes for
intracellular targeting, particularly actin and nuclear DNA, via
correlative light and liquid phase electron microscopy (CLLEM) .