IPA 2021 Photogenic Science Contest Winners

Category: Basic Science

Title: Crystals of photoactive BODIPY dye in pattern spreading as tree branches in a flask

Winner: Bhavya Khurana
PhD student at Trinity College Dublin (Senge Group) and University of Limoges (Peirene Lab)

Crystal growth is a crucial step in characterizing a new molecular compound - a good quality crystal allows the determination of the structural details of the desired compound through X-ray diffraction. A crystalline form of a drug affects properties such as its bioavailability, stability, solubility, dissolution rate, and bioavailability, and the crystalline state of a drug is crucial to understand the pharmacology behind the molecule and its commercialization in industry.(1)

Boron dipyrromethene (BODIPY) dyes have sharp absorption and fluorescence emission bands in the red or NIR region of the spectrum. They have high molar absorption coefficients along with high fluorescence quantum yields. This is why they have been extensively used in fields such as optical engineering, analytical chemistry, biological in vivo imaging and sensing applications, as well as materials science.(2) In my project, a series of BODIPY dyes functionalized with N-heterocycles were synthesized to study the photoinactivation of pathogenic microbiome with these dyes.

© 2021 Bhavya Khurana
Crystals of photoactive BODIPY dye in pattern spreading as tree branches in a flask

The images shows the crystal growth of a newly synthesized BODIPY dye [8-(2-quinolinyl)-1,3,5,7-tetramethyl-BODIPY], obtained using the vapour diffusion method of crystallization with hexane and ethyl acetate. The crystal growth was achieved in four days at room temperature. After this photo was taken, one of these crystals was mounted on an X-ray diffractometer, diffraction data were collected and used to determine the atomic positions within the crystalline repeating unit. Determination of atom-scale structure of molecules is important to understand their biological and photochemical behaviour. Identification of bonding patterns within molecules, as well as their conformation, helps to assign electron density and informs spectroscopic investigations. Understanding the intermolecular interactions engaged by species can explain how they may act on surfaces or in biologically relevant environments, and in our case, antimicrobial photodynamic activity (aPDT). Finally, a crystal structure represents the gold standard of certainty in molecular assignment. These crystals, when precipitated, are arranged in a beautiful pattern like fluorescent leaves on tree branches. These branches, in my perspective, have been interpreted as branches of hope, as their efficiency as antimicrobial agents for aPDT is an important application for today’s world problems.

References:

1. Taylor, L.S.; Braun, D.E.; Steed, J.W. Crystals and Crystallization in Drug Delivery Design. Cryst. Growth Des. 2021, 21, 1375–1377.
2. Leen, V.; Qin, W.; Yang, W.; Cui, J.; Xu, C.; Tang, X.; Liu, W.; Robeyns, K.; Van Meervelt, L.; Beljonne, D.; et al. Synthesis, Spectroscopy, Crystal Structure Determination, and Quantum Chemical Calculations of BODIPY Dyes with Increasing Conformational Restriction and Concomitant Red-Shifted Visible Absorption and Fluorescence Spectra. Chem. – An Asian J. 2010, 5, 2016–2026

Category: Pre-Clinical Science

Title: Nano Death

Winner: Nidia Maldonado Carmona
PhD student at University of Limoges (Peirene Lab) and University of Coimbra (Chemical Center of Coimbra)

© 2021 Nidia Maldonado Carmona
Nano Death

Unlike traditional chemotherapies, Photodynamic Antimicrobial Chemotherapy seeks to use light as a condition for the disinfection of bacteria. For instance, it relies on the use of light, a photosensitizing molecule and oxygen, which together generate cytotoxic reactive oxygen species, leading to bacterial death. Photosensitizing molecules, being planar molecules, tend to aggregate on aqueous media, and thus, the development of delivery systems can increase the bioavailability of photosensitizers (PSs). In this multidisciplinary project, we encapsulated a porphyrinic compound (5,10,15,20- tetrakis(hydroxyphenyl)-21,23-H-porphine, THPP) inside spherical acetylated lignin nanoparticles, aiming at the transport of PSs and the valorization of lignin, an abundant renewable resource. Interestingly, we observed that THPP kept its photophysical properties, namely absorbance, fluorescence emission and, most importantly, light-driven singlet oxygen production. Furthermore, the formulation inside acetylated lignin nanoparticles demonstrated to be stable, as THPP did not leak over time, or degrade when exposed to different pH and irradiation conditions. The successful results prompted to test the THPP-loaded nanoparticles against bacteria, resulting in efficient annihilation of Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis), while being inefficient against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa).

To further understand the interaction between bacteria and nanoparticles, we went to the microscopic level, through a collaboration with Wrocław University of Science and Technology. We exposed S. aureus cells to a suspension of THPP-loaded nanoparticles, and together with Dr. Andrzej Żak we observed that nanoparticles tightly bound to the surface of bacteria. More interestingly, when we irradiated with light the suspension of nanoparticles and bacteria, we found that bacteria were dying due to the apparent burst of their bacterial envelopes. This allowed us to find NanoDeath, where we could observe that nanoparticles, as small spherical bodies, were still bound to the envelope of an already-burst cell, which was pouring its contents to the media. In this micrography, we were able to observe the cellular content coming out of the cell.

Reference:

Maldonado-Carmona N, Marchand G, Villandier N, Ouk T-S, Pereira MM, Calvete MJF, Calliste CA, Żak A, Piksa M, Pawlik KJ, Matczyszyn K, & Leroy-Lhez S (2020) Porphyrin-Loaded Lignin Nanoparticles Against Bacteria: A Photodynamic Antimicrobial Chemotherapy Application. Front Microbiol. https://doi.org/10.3389/fmicb.2020.606185

Category: Clinical Science

**Alexander Dushkin**
Clinical resident at The Loginov Moscow Clinical Scientific Center (Oncology) and postgraduate student at Sechenov University (Clinical Immunology and Allergy)

Title: PDT on the guard of your health

Winner: Alexander Dushkin
Clinical resident at The Loginov Moscow Clinical Scientific Center (Oncology) and postgraduate student at Sechenov University (Clinical Immunology and Allergy)

© 2021 Alexander Dushkin
PDT on the guard of your health

Clinical illustration of cervix Photodynamic Therapy (PDT). PDT is based on the use of three fundamental scientific fields - chemistry, physics and biology. The biological part of PDT consists of the accumulation of the photosensitizer (PS) in pathological tissues and cells. The physical part of PDT is light energy transmission from the PS, and oxygen transformation from molecular to reactive oxygen species (ROS).

The chemical part includes photochemical reactions which occur among ROS and intracellular biomolecules. PDT can activate the human’s immune system, inducing programmed cell death in pathological and tumor cells. PDT is a very selective procedure. This image, of a non-invasive cervical cancer treatment using PDT, demonstrates digital proof of the high-quality procedure. A doctor uses a PS and light exposure. PDT can also be used for cancer diagnosis by means of theragnosis. PDT in combination with fluorescence diagnostics, computer vision and image recognition of colposcopy increases the sensitivity and specificity of pathological area detection.

More than 1,200 women avoid surgery and preserve fertility thanks to photodynamic theranostic. A successful PDT approach protect the cervix from relapse and human papillomavirus elimination. (1) PDT may provide antiviral and antitumor immunity. We hope our research makes patients’ lives better in the future.

References:

Afanasiev, M. S., Dushkin, A. D., Grishacheva, T. G., Afanasiev, S. S., & Karaulov Academician, A. v. (2021). Photodynamic therapy for early-stage cervical cancer treatment. Photodiagnosis and Photodynamic Therapy, 102620. https://doi.org/10.1016/j.pdpdt.2021.102620

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