methylene blue
methylene blue
Overview
Methylene blue is a synthetic phenothiazine dye with long-standing biomedical relevance. In medicine, it is best known as a redox-active compound that can participate in electron-transfer reactions and, under appropriate light exposure, act as a photosensitizer. These properties have made it useful in diverse experimental and clinical contexts, including imaging, photodynamic therapy, and assay development. In the research contexts provided here, methylene blue appears primarily as a functional probe or therapeutic adjunct rather than as a disease target in the classical molecular sense.
Biologically, methylene blue is notable for its ability to interact with biomolecules through adsorption, labeling, and light-activated reactive oxygen species generation. Recent studies also continue to use it as a model cationic dye in materials science and environmental chemistry, where its removal or degradation serves as a benchmark for adsorption and photocatalytic performance. Across the cited publications, methylene blue is therefore positioned at the intersection of diagnostics, phototherapy, and dye-remediation research.
Focus of Latest Publications
Recent publications on methylene blue focus mainly on two themes: its use in photodynamic cancer therapy and its role as a target dye in adsorption, photocatalysis, and sensing platforms. In oral squamous cell carcinoma, methylene blue-mediated photodynamic therapy was investigated as a potential treatment approach, with the study specifically evaluating whether metformin could potentiate the photodynamic effect against tongue cancer cells in vitro and exploring possible molecular mechanisms. This work reflects continued interest in improving photochemotherapy strategies for head and neck malignancies.
Several studies examined methylene blue removal from water using engineered adsorbents. A cellulose-based composite hydrogel cross-linked with gelatin and alkali lignin showed selective adsorption of cationic dyes, with methylene blue adsorption optimized at pH 6.0, 0.02 g adsorbent dosage, and 30 °C, reaching 103.33 mg/g within 12 h. Another ternary hydrogel incorporating covalent organic framework, carboxylated cellulose nanofibers, and water hyacinth carbon achieved very high methylene blue uptake, with a maximum adsorption capacity of 1054.10 mg/g and good reusability over five adsorption-desorption cycles. A bacterial cellulose aerogel functionalized with polydopamine and polyethyleneimine also removed methylene blue efficiently, with a maximum adsorption capacity of 92.22 mg/g, alongside strong performance for copper(II) and Congo Red. A guar gum/β-cyclodextrin composite hydrogel with phosphorylated ginkgo charcoal similarly showed high-capacity removal of methylene blue, with a Langmuir-model capacity of 879.41 mg/g and stable performance over repeated cycles.
Other publications used methylene blue as a model pollutant to evaluate photocatalytic materials. ZnO nanoparticles synthesized from pomegranate peel extract degraded methylene blue under light, with the best-performing sample showing a photocatalytic rate constant of 0.065 min-1. Biosynthesized MgO nanoparticles from Chromolaena odorata and Hevea brasiliensis extracts were also tested for photocatalytic degradation of methylene blue under sunlight, with the Chromolaena odorata-derived material achieving higher degradation and mineralization. These studies position methylene blue as a standard probe for assessing photocatalytic efficiency in green nanomaterials.
Methylene blue also appeared in a biosensing context as a labeled component of aptamers in an electrochemiluminescence platform for extracellular exosome detection. In that system, target recognition triggered desorption of methylene blue-labeled aptamers, producing signal recovery and enabling ultrasensitive detection of MCF-7 exosomes, with automated phenotype discrimination supported by machine learning analysis.