A review of career devoted to biophotonics-in memoriam to Ekaterina Borisova (1978-2021)

Regretfully, because of her sudden demise, Assoc. Prof. Ekaterina Borisova is no longer amongst us. COVID-19 pulled away a brilliant scientist during the peak of her scientific career (see Fig. 1). All authors would like to express deepest condolences and sincere support to her family, friends, relatives and colleagues! We, therefore, rightfully commemorate her dedicated and devoted contribution to biophotonics, her readiness to always support, help, motivate and inspire all her colleagues and collaborators

Polarization-Based Digital Histology of Human Skin Biopsies Assisted by Deep Learning

Mueller polarimetry has proven to be a powerful optical technique to complement medical doctors in their conventional histology analysis. In this work, various degenerative and malignant human skin lesions were evaluated ex vivo using imaging Mueller polarimetry. The Mueller matrix images of thin sections of biopsies were recorded and the differential decomposition of Mueller matrices was applied pixel-wise to extract the polarization fingerprint of the specimens under study. To improve the classification accuracy, a deep learning model was created. The results indicate the sensitivity of polarimetry to different skin lesions and healthy skin zones and their differentiation, while using standard histological analysis as a ground truth. In particular, the deep learning model was found sufficiently accurate to detect and differentiate between all eight classes in the data set. Special attention was paid to the overfitting problem and the reduction of the loss function of the model. Our approach is an effort in establishing digital histology for clinical applications by complementing medical doctors in their diagnostic decisions

Phospholipase A₂‑Induced Remodeling Processes on Liquid-Ordered/Liquid-Disordered Membranes Containing Docosahexaenoic or Oleic Acid: A Comparison Study

Vesicle cycling, which is an important biological event, involves the interplay between membrane lipids and proteins, among which the enzyme phospholipase A₂ (PLA₂) plays a critical role. The capacity of PLA₂ to trigger the budding and fission of liquid-ordered (L_o) domains has been examined in palmitoyl-docosahexaenoylphosphatidylcholine (PDPC) and palmitoyl-oleoylphosphatidylcholine (POPC)/sphingomyelin/cholesterol membranes. They both exhibited a L_o/liquid-disordered (L_d) phase separation. We demonstrated that PLA₂ was able to trigger budding in PDPC-containing vesicles but not POPC ones. The enzymatic activity, line tension, and elasticity of the membrane surrounding the L_o domains are critical for budding. The higher line tension of L_o domains in PDPC mixtures was assigned to the greater difference in order parameters of the coexisting phases. The higher amount of lysophosphatidylcholine generated by PLA₂ in the PDPC-containing mixtures led to a less-rigid membrane, compared to POPC. The more elastic L_d membranes in PDPC mixtures exert a lower counteracting force against the L_o domain bending