Katarzyna Matczyszyn

Four organometallic porphyrins with outstanding two-photon absorption properties are reported. Two of them were successfully used in vitro for anti-cancer phototherapy with MCF-7 cell lines via encapsulation in PLMABe ₇₃ nanoparticles.

Engineering light-responsive nanoparticles (NPs) with tailored nonlinear optical properties is opening new opportunities in precision biophotonics.

Plasmonic‐photochromic materials have been widely investigated to harness photoresponsive properties of both components, particularly in systems comprising gold nanoparticles (AuNPs) and azobenzenes (Azos). Although AuNPs affect Azo performance, there is no information on how to employ their morphology to systematically modulate kinetics and thermodynamics of the photochromes. Herein, we utilize cellulose decorated with Azo and gold nanorods (AuNRs) of different aspect ratio (AR) to present how material design can affect the performance of photoresponsive systems. The size‐dependent catalytic effect of AuNRs is manifested during UV–vis and dark isomerization of Azo with rate constants inversely related to the AR. Comparison of spectroscopic and microscopic data indicates LSPR shifts and subtle shortening of AuNRs upon repeated photoswitching (2.513–2.505 AR decrease for one of the samples), thus confirming electron and energy transfer as catalytic enhancement mechanisms. Finally, Azo dark isomerization rate constants are juxtaposed with structural parameters of the material derived from AR, including total surface area or number of nanoparticles. The average relative differences between structural parameters equal 22% if AuNRs with highest versus lowest AR are compared, while the kinetic differences reach 50% on average. These results indicate that the observed size effect is a convolution of several structural descriptors.

Exploiting the unique anisotropy and fluidity of liquid crystals (LCs) enables the design of advanced hybrid nanomaterials for photonic applications. The intrinsic long-range order of the LCs matrix can act as a structural template, directing nanoscale dopants into well-defined geometrical configurations and enabling precise control over nanoparticle distribution. Here, we use an inverted hexagonal phase (H2) of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), p-xylene, and a water dispersion of gold nanorods (AuNRs) to fabricate well-ordered nanomaterial assemblies. Scanning transmission electron microscopy of thin films reveals AuNR chains extending up to 30 μm in length with a mean interparticle spacing of about 5 nm and a 2D order parameter S2D = 0.96 ± 0.10. Correlative multiphoton and polarizing microscopy demonstrate a uniform arrangement of AuNRs within the central region of the sample thickness, particularly at the domain boundaries. The performed nanostructural characterization suggests the ordering mechanism and highlights the impact of anchoring forces on nanorod ordering and microstructure formation in the bulk sample.

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Bisphenol A (BPA) is a widely used additive in the manufacture of plastics, including polycarbonate, polyvinyl chloride, epoxy, and polyester resins. While BPA is used as an effective plasticizer, ...

Combining reversible optical control with structural sensing of G-quadruplex (G4) DNA remains a significant challenge for nucleic acid-targeting photoswitches. Herein, we report the synthesis and photophysical characterization of a visible-light-responsive ortho-fluoroazobenzene derivative, exAzoPy2, designed to modulate G4 DNA structures. The interaction of exAzoPy2 with unfolded and folded G4 topologies was investigated using circular dichroism (CD) and fluorescence spectroscopy. The photoswitch exhibits isomer-dependent effects on antiparallel G4 structures: the cis-rich photostationary state promotes G4 folding, whereas photoinduced cis-to-trans isomerization favors the unfolded state. In addition to structural modulation, exAzoPy2 generates topology- and isomer-dependent induced circular dichroism (ICD) signals in the ligand absorption region. Distinct ICD responses depend on DNA conformation and G4 topology, enabling chiroptical discrimination of different G4 states. The combination of visible-light responsiveness, reversible structural modulation, and ICD-based spectroscopic readout highlights exAzoPy2 as a photoswitch capable of both controlling and sensing different G4 DNA architectures.

Antimicrobial photodynamic therapy (aPDT) is a promising alternative to antibiotics, yet the molecular factors determining bacterial susceptibility remain unclear. This study investigates the critical role of bacterial lipids, particularly cardiolipin (CL) in the aPDT response of Escherichia coli using methylene blue as a photosensitizer. Through genetic deletion (ΔclsABC) and chemical modification via mannitol supplementation, we demonstrate that reduced CL levels significantly enhance bacterial sensitivity, leading to an additional reduction in viability exceeding 3 log10. Quantitative lipidomics (MS,GC) confirmed substantial CL depletion and altered fatty acid saturation. Interestingly, while live CL-deficient cells were more vulnerable, biomimetic giant unilamellar vesicles (GUVs) with higher CL content showed greater susceptibility to photo-oxidation. These findings suggest that CL-rich microdomains in living bacteria act as functional scaffolds for stress-defense systems rather than mere targets for oxidative damage. Modulating membrane lipid composition thus represents a novel strategy to potentiate aPDT efficacy.

We report the use of σ-alkynyl d⁶ electron-rich transition metal complexes as electron-releasing end-groups in octupolar molecules designed for nonlinear optical (NLO) applications, specifically, N,N′,N″-triarylisocyanurates (5,7,8,10,12) and 1,3,5-triarylbenzenes (6,9,11) functionalized by Fe(II) and Ru(II) organometallic moieties, and their NLO properties, as assessed by hyper-Rayleigh scattering (HRS) and Z-scan. The redox properties are briefly investigated through isolation of the corresponding Fe(III) trications 5[PF₆]₃ and 6[PF₆]₃. The second-harmonic generation (SHG) or two-photon absorption (2PA) performance of the Fe(II) and Ru(II) parents is compared with the help of TD-DFT calculations performed on models. Comparison with tris-ferrocenyl isocyanurate 4 reveals that the σ-connection of the metallic centers to the π-manifold is superior to the η⁵-connection for enhancing NLO properties. The positive effect of organometallic end-groups on NLO properties relative to purely organic electron-releasing substituents is established. The mechanism by which NLO enhancement occurs is complex and possibly connected to the polarizable π-electrons in the ligands surrounding the metal alkynyl units, but in most cases, the observed NLO enhancement must arise from the transition metal centers interacting with the central π-manifold.

G-quadruplex (G4)-targeted photosensitizers (PSs) are advancing precision oncology by confining DNA damage to malignant cells while sparing healthy tissue. Yet, molecular-level studies on the mechanisms and dynamics of G4 structure damage under PSs light-activation are limited. Here, we introduce DBI-POE, an activatable, heavy-atom-free PS derived from the G4-specific sulfur-substituted dibenzothioxanthene imide (S-DBI) and modified with a hydrophilic, bio-compatible polyoxyethylene (POE) side chain. In aqueous solution, owing to its amphiphilic character, DBI-POE self-assembles into nanoaggregates that disassemble upon binding to G4 DNA. This disassembly switches its photophysical behavior “turning on” its fluorescence while enabling two-photon near-infrared (NIR) excitation. Moreover, while DBI-POE follows a type I pathway in the aggregated state, producing superoxide anion (O₂˙⁻) and hydroxyl (OH˙) radicals, it shifts to a type II mechanism that predominantly generates singlet oxygen (¹O₂) upon G4 binding. The generated ¹O₂ selectively oxidizes guanine residues, triggering G4 unfolding, a mechanism validated through biophysical experiments, dot blot assay and molecular dynamics (MD) simulations. Furthermore, biochemical experiments at single-base resolution reveal that photoactivated DBI-POE induces site-specific oxidative lesions at G4 sites, stalling DNA polymerase, while non-G4 regions remain unaffected. This combination of supramolecular disassembly, photophysical pathway switching, and G4-selective oxidative damage underscores the high specificity of DBI-POE, opening new avenues for the design of next-generation G4-targeted PSs for photodynamic cancer therapies.