Marcos Palmeira

Reactive Oxygen Species Detection with Fluorescent Probes: Limitations and Recommendations beyond DCFH-DA Reactive oxygen species (ROS) are highly reactive molecules derived from molecular oxygen that play critical roles in cellular signaling, homeostasis, and the regulation of various physiological and pathological processes. Accurate detection and quantification of ROS are essential for elucidating their roles in health and disease. Despite significant advances in ROS probe development, challenges persist due to their short lifetimes, high reactivity, and their chemical diversity. This perspective article provides a critical evaluation of the limitations of the most commonly applied probe molecule DCFH-DA. Capitalizing on this, recommendations with practical applications in the lab for the specific detection of hydrogen peroxide, hydroxyl radical, singlet oxygen, superoxide anion, and peroxynitrite are provided. By integrating current knowledge on ROS probe technologies, this work aims to guide researchers in reliably assessing ROS in complex biological systems, thereby facilitating a deeper understanding of ROS-mediated processes and their implications for disease research and therapeutic development.

Check out our perspective in J. Med. Chem. @acsmedi.bsky.social about the Limitations of DCFH-DA for the Detection of ROS and Recommendations for Probe Selection. @ruhr-uni-bochum.de dx.doi.org/10.1021/acs....

Happy to see this collaborative with Hui Chao and @kargesgroup.bsky.social out in @angewandtechemie.bsky.social. We designed Ir(III) complexes to trigger oncosis and activate the cyclic GMP–AMP synthase-stimulator of interferon genes pathway.
@chimieparistechpsl.bsky.social
doi.org/10.1002/anie...

I’m happy to share that I’m part of the Royal Society of Chemistry membership community with my digital credential. @rsc.org #RSCMembership #RSC

Inverse Correlation between Endoplasmic Reticulum Stress Intensity and Antitumor Immune Response with Ruthenium(II)-Based Photosensitizers for the Photodynamic Therapy of Head and Neck Squamous Cell Carcinoma Photodynamic therapy (PDT) is a promising strategy for head and neck squamous cell carcinoma (HNSCC), but the immune consequences of tumor cell death remain incompletely understood. We compared two ruthenium(II) polypyridine photosensitizers (PSs) in HNSCC models and found that both were potently phototoxic (nanomolar IC50s), triggered diverse cell death pathways (including autophagy and ferroptosis), and promoted hallmark danger signals of immunogenic cell death (ICD). Strikingly, only one PS induced apoptosis and strong endoplasmic reticulum (ER) stress, yet paradoxically led to immune tolerance in vivo. Conversely, the PS that did not induce apoptotic cell death with milder stress responses resulted in a better antitumor immunity in vivo. These unexpected findings challenge the prevailing view that PDT-triggered apoptosis and ER stress are essential for ICD. Our study underscores the complexity of PDT-induced cell death balance and immunogenic signals and highlights the need to redefine ICD-inducing criteria for the rational design of next-generation PSs.

Thrilled to announce that the last two collaborations from my postdoc in the @gassergroup.bsky.social are now published in J. Med. Chem. and JACS. ⚗️🧪
Congrats to all co-authors for the excellent work!
pubs.acs.org/doi/10.1021/...
pubs.acs.org/doi/abs/10.1...

🚨 PhD Opportunity! 🚨
Join our group in Bioinorganic Chemistry to work on the synthesis & biological evaluation of metal complexes for anticancer therapy.
jobs.ruhr-uni-bochum.de/jobposting/8...

Palladium(II) Complexes with Noncovalent Interactions with DNA: Solution Speciation Controlled by Solvent Identity, pH, and Concentration The coordination capacity of thiosemicarbazone ligands and their synergism with palladium(II) ions modulate their reactivity, allowing custom design. Using thiosemicarbazones with two potential stable...

Read our last open access publication with @medbioinorgchem.bsky.social @gmalcantar.bsky.social thanks to @costactionnectar.bsky.social doi.org/10.1021/acs....

Selection of Ruthenium Polypyridyl Complex-Modified Aptamers for Photodynamic Therapy against Streptococcus Pneumonia Photodynamic therapy (PDT) harnesses the combination of light, oxygen, and photosensitizers to induce cell death via reactive oxygen species (ROS) formation. Given its intrinsic properties, PDT repres...

Thrilled to share our article just published in @J_A_C_S on the selection of Ru-modified aptamers! Fantastic collaboration with @hollensteinlab.bsky.social, congratulations to all authors! doi.org/10.1021/jacs...

Excited to share our new @inorgchemfront.rsc.org article about Ruthenium-phosphine complexes as cytotoxic agents against breast cancer. Congrats all team! @ufscar.bsky.social @pesquisafapesp.bsky.social @agenciafapesp.bsky.social

doi.org/10.1039/D5QI...

Starting the year with our work published at JIB! Check out this big contribution to medicinal inorganic chemistry on anticancer Ru(II)-phosphine complexes. Congrats all team! #JIB #inorganicchemistry #cancer dx.doi.org/10.1016/j.ji... @ufscar.bsky.social @agenciafapesp.bsky.social

Exciting News!🎉

@kanishkasikligar.bsky.social & I are co-chairing the Metals in Medicine GRS 2026-Transforming Medicine with Inorganic Chemistry! 🧪 🔬💊

A must for early-career researchers to explore cutting-edge science & network. Join us in June 2026! 👇
🔗 lnkd.in/e7JJYY3R

Photoactivatable Cyclometalated Ir(III) Compound Penetrates the Blood-Brain Barrier in 3D Spheroidal and Advanced 3D Organoid Models of Inherently Resistant and Aggressive Brain Tumors The blood-brain barrier represents a significant challenge in delivering anticancer drugs for glioblastoma treatment. The study investigates the potential of a series of octahedral photoactivatable cyclometalated iridium complexes (Ir1–Ir10) with the general formula [Ir(ttpy)(C∧N)Cl]PF6 as photoactivated therapy candidates for the treatment of this aggressive tumor. These complexes, which include the terdentate ligand 4′-(p-tolyl)-2,2′:6′,2″-terpyridine (ttpy), and a C∧N ligand based on the deprotonated 2-arylbenzimidazole backbone, were tested on human glioblastoma using 2D cell cultures and 3D spheroidal models, including a fusion system comprising cerebral organoids from nonmalignant human-induced pluripotent stem cells and spheroids derived from malignant brain cells. The iridium complexes catalyze NADH photooxidation and photogenerate 1O2 and/or •OH under blue light irradiation. Blood-brain barrier penetration was assessed using various in vitro models. The complex Ir4, containing deprotonated methyl 1-butyl-2-phenylbenzimidazolecarboxylate, shows promise for targeted therapy of resistant brain tumors when photoactivated with blue light. Ir4 induces rapid and sustained ROS-mediated cytotoxicity and selectively accumulates in tumor tissue. This suggests its potential for fluorescently guided-PDT cooperative resection of glioblastoma. Notably, Ir4 significantly reduces glioblastoma growth even under dark conditions compared to conventional Temozolomide treatment without affecting healthy brain tissue.

Glad to share our last studies in collaboration with Viktor Brabec.
Photoactivatable Ir(III) Compound Penetrates the Blood-Brain Barrier in 3D Spheroidal and Advanced 3D Organoid Models of Inherently Resistant and Aggressive Brain Tumors | ACS Pharmacol & Transl Science pubs.acs.org/doi/full/10....

Our review just got a cover feature!✨
I’m so happy to share it, I had a great time illustrating the cover art! Thanks to Diego for the help!
Metal–coumarin derivatives as promising photosensitizers for cancer phototherapy. @joseruizlab.bsky.social @inorgchemfront.rsc.org

Check out our study in @acsmedi.bsky.social about the "Induction of Cuproptosis with a Highly Cytotoxic Tripodal Cu(II) Complex". Congrats to Ricarda and @nmontesdeocas.bsky.social @ruhr-uni-bochum.de
pubs.acs.org/doi/abs/10.1...

Check out our paper in J. Med. Chem. @acsbiol.bsky.social @acsmedi.bsky.social about the induction of immunogenic cell death by a gallium complex for chemoimmunotherapy. Congrats to Zisis and Yassin! @ruhr-uni-bochum.de
dx.doi.org/10.1021/acs....

Check out our paper in @inorgchemfront.rsc.org about the Induction of Oncosis by Light Activation with an Ir(III) complex conjugated to Albumin. Congrats to Antonio, Zisis, and Lisa. Fantastic collaboration with @joseruizlab.bsky.social ! @ruhr-uni-bochum.de @um.es dx.doi.org/10.1039/D5QI...

Exploring the toxicity of mononuclear piano-stool Ru(II) anticancer agents: A comprehensive literature review Piano-stool Ru(II) complexes have emerged as a promising class of anticancer agents characterized by structural modularity and diverse cytotoxic activ…

An idea that took root during the COVID lockdown has finally come to life, thanks to the invaluable help of Martin Sojka (former postdoc in our group and now early-career leader at the IPM Brno), who helped me in writing this review on ruthenium(II) piano-stool complexes.

tinyurl.com/yxzshnn5

🌎Dreaming of studying engineering in France? The 2025 ParisTech International Admission Program is OPEN!

Join one of the top French Grandes Écoles, live in Paris, and earn a Master-level engineering degree recognized worldwide.

⬇️ Apply now!
paristech.fr/en/internation…

I am extremely grateful to receive this award. Many thanks to the LABIC scientific committee. Looking forward to the next conference in Brazil. See you soon @agenciafapesp.bsky.social #Chemsky #science

Today in Chemistry History graphic on Rosalind Franklin and the structure of DNA. Rosalind Franklin was a chemist and X-ray crystallographer whose work was instrumental in the discovery of the structure of DNA. She missed out on a Nobel Prize for her work as they are not awarded posthumously. Photograph 51 is an X-ray diffraction image of DNA taken during Franklin’s research. It was crucial in developing a model of DNA and confirming its double helical structure.

Rosalind Franklin was born #OTD in 1920. She was a chemist and crystallographic who made a key contribution to the discovery of the double helix structure of DNA: www.compoundchem.com/2017/07/25/f...

#ChemSky 🧪

Apolline presenting at the Consortium Antiparasitaire et Antifongique in Lille

Brillant presentation by Apolline @apolloniakal.bsky.social at CAPF25 in Lille on our latest results on anti-infectious drugs @gassergroup.bsky.social @chimieparistechpsl.bsky.social @psl-univ.bsky.social @cnrs.fr with our collegues in Nantes (@agencerecherche.bsky.social) and Uruguay.

Light-Induced Synthesis and Radiotheranostic Treatment of Gastric Cancer with 161Tb-Labeled Monoclonal Antibodies Radiolabeled monoclonal antibodies (mAbs) form a major branch of nuclear medicine and are used in the development of tracers for both diagnostic imaging and molecularly targeted radio(immuno)therapy (RIT). Since treatment options for many types of late-stage cancers are limited and these diseases become refractory to classic chemotherapy, new tools are required to improve patient outcomes. The high tumor uptake and specificity of mAbs, coupled with increased therapeutic range of energetic β–-emitting radionuclides, offers a potential solution to overcome traditional problems associated with poor tissue penetration of antibody-drug conjugates, chemotherapeutic resistance, and off-target accumulation, which can lead to adverse responses. The challenge is to develop efficient and reliable chemical methods that provide simultaneous selectivity and high stabilization of the radiometal via complexation chemistry, with rapid access to new bioconjugate bonds on protein that avoid the loss of bioactivity. Here, we designed a new octadentate bispidine-chelating system, functionalized with a light-responsive tetrazole unit, and demonstrated the chemoselective derivatization of sulfhydryl groups introduced on the protein surface. High radiolabeling and bioconjugation yields of 161Tb-onartuzumab─an engineered mAb fragment targeting the human hepatocyte growth-factor receptor (c-MET; a characteristic biomarker found in clinical samples of several diseases, including gastric adenocarcinomas)─were obtained under ambient conditions after 5 min of light-induced coupling. Comprehensive biochemical and animal experiments including cellular binding assays, noninvasive γ-ray imaging, biodistribution studies, and pharmacokinetic measurements established the viability of using 161Tb-onartuzumab to target c-MET expression in vivo. Subsequent RIT studies in MKN-45 xenograft models demonstrated that the 161Tb-onartuzumab radiotracer formed by photoradiosynthesis permitted low-dose therapy studies that led to efficient targeting and treatment of tumor models. Collectively, the new complexation and chemoselective photoconjugation chemistries overcome some of the limitations in traditional labeling approaches. Photoradiosynthesis represents an excellent platform for building future antibody-based radiotracers for applications in diagnostic and therapeutic medicine.

Happy to share that my second paper from the @hollandlab.bsky.social is online now! We have discovered a new bioconjugation strategy and have tested it in terms of Radioimmunotherapy with Tb-161!

Thanks to all authors!

doi.org/10.1021/jacs...

Should you wish to attend a cool workshop in a cool city, this is the one you should go for! #structuralbiology

Harnessing Organometallic Gold(III) Complexes as Precision Scaffolds for Next‐Generation Therapeutic and Imaging Agents Gold(III) organometallic complexes, particularly cyclometalated Au(III) compounds, have emerged as powerful tools in catalysis and bioinorganic chemistry, offering unique reactivity distinct from the...

Our new paper is out in #chembiochem!
Even more special because it was coauthored with my longtime friend and collaborator @sophierthomas.bsky.social
Always a pleasure to turn shared ideas into shared results ❤️
🔗 doi.org/10.1002/cbic...

Photodynamic therapy photosensitizers and photoactivated chemotherapeutics exhibit distinct bioenergetic profiles to impact ATP metabolism Energy is essential for all life, and mammalian cells generate and store energy in the form of ATP by mitochondrial (oxidative phosphorylation) and non-mitochondrial (glycolysis) metabolism. These pro...

Congrats to @richardmitchell210.bsky.social for an excellent study leveraging metabolic analysis! This paper shows how photodynamic therapy photosensitizers and photoactivated chemotherapeutics exhibit distinct bioenergetic profiles - now in Chemical Science (a 🧵) pubs.rsc.org/en/content/a...

It was very nice to hear the presentation of Prof. Eduardo Sousa from the University Ceará in Fortaleza in 🇧🇷 and to discuss with him and Prof. Luiz Lopes! Exciting collaboration ahead.

👏🏼👏🏼👏🏼

Gold metallacages: Design principles and applications Metallacages (MCgs) are three-dimensional (3D)-supramolecular coordination complexes (SCCs) obtained by the self-assembly of metal ions with donor lig…

Our new paper is here!! "Gold #metallacages: Design principles and applications". With the contribution of @sophierthomas.bsky.social, Nina Willnhammer and @medbioinorgchem.bsky.social. Check it out #Openaccess in @cp-chem.bsky.social. www.sciencedirect.com/science/arti... enjoy the read!! @tum.de

UFSCAR APROVA COTAS TRANS 🏳️‍⚧️

Recebi, com enorme felicidade, a notícia de que a UFSCar, Universidade na qual estudei, aprovou cotas pra pessoas trans.

Com isso, cada um de seus cursos de graduação passará a oferecer uma vaga extra, destinada às pessoas trans.

Vem entender +👇🏽

Spotlight on cancer immunotherapies go.nature.com/3XUTPkM

Thank you! 🎉