In the present study, two types of graphene quantum dots (GQDs) were investigated: green-emitting (G-GQDs) and blue-emitting (B-GQDs). Physicochemical characterisation was performed using transmission electron microscopy (TEM), zeta potential, and hydrodynamic radius measurements to evaluate the morphology, particle size, aggregation behaviour, and colloidal stability of the GQDs in both water and cell culture medium. G-GQDs exhibited superior colloidal stability and more uniform dispersion than B-GQDs, whereas both types showed reduced aggregation and surface charge in cell culture medium due to protein corona formation. Toxicological characterisation was performed using an in vitro human hepatocellular carcinoma (HepG2) 3D spheroid model, with GQDs exposures up to 250 µg/mL (100 µg/cm2). Cytotoxicity was measured using the CellTiter-Glo luminometric assay, while genotoxicity was evaluated by the comet assay and flow cytometric analysis of γH2AX and phosphorylated histone H3 (p-H3) after 24 h of exposure. Both GQDs induced dose-dependent cytotoxic effects in HepG2 spheroids. At non-cytotoxic concentrations, a dose-dependent increase in DNA damage was observed, as determined by the comet assay. However, no evidence of DNA double-strand breaks (γH2AX) or elevated p-H3 levels was detected, suggesting the absence of clastogenic and aneugenic activity. The observed DNA single-strand breaks may be partly attributed to reactive oxygen species induction. These results indicate that, although GQDs induced cytotoxicity and single-strand DNA damage, no clear evidence of more severe genotoxic effects was observed under the tested conditions. Further studies are warranted to elucidate underlying mechanisms and comprehensively assess the safety profile of GQDs for biomedical applications.

Spontaneous chromosomal aberrations are structural or numerical changes of chromosomes that occur naturally, without exposure to external genotoxic factors. They are not inherited, occur randomly in the karyotype, and do not have direct clinical significance. However, they can affect genomic instability and disease predisposition. They can result from DNA replication or repair processes errors, and typically are observed in cells that are actively dividing. Spontaneous chromosomal aberrations may arise due to the natural chromosomal instability and can be elevated in individuals exposed to mutagens. We analyzed frequencies of spontaneous chromosomal aberrations in 137 individuals subjected to karyotype analysis at the Laboratory for Cytogenetics and Genotoxicology, University of Sarajevo – Institute for Genetic Engineering and Biotechnology, during 2008-2023. Whole blood samples were cultivated for 72 hours with the thymidine added in the 48th hour. Metaphases were arrested by colcemid 60 minutes before harvesting. GTG banding was performed and slides were analyzed under 1000x magnification in accordance with An International System for Human Cytogenetic Nomenclature and E.C.A. Cytogenetic Guidelines and Quality Assurance. Constitutionally aberrant karyotypes were found in 2.92% of analysed individuals as well as altered karyotypes considered as normal chromosomal variants. In the total of 3092 analyzed metaphases, 20 spontaneous chromosomal aberrations were found in 13 individuals. This study contributes to the limited knowledge of the cytogenetic status of the Bosnian and Herzegovinian population. Further monitoring of spontaneous chromosomal aberrations incidences is recommended.

Background Waterpipe, also known as a hookah or narghile, is a type of tobacco products consumption device. Recently it has been increasingly popular in Bosnia and Herzegovina and the region. Waterpipe consumers are predominantly adolescents and young adults. Many of them believe in slighter harmful effects of waterpipes, compared to cigarettes. We aimed to determine the DNA damage in oral leukocytes and buccal cells of young individuals who have smoked a waterpipe for more than one year. Methods The study group consisted of 40 cigarette non-smokers who regularly smoked a waterpipe on average of once per week. As a control, 40 non-smoking individuals were selected to match smokers for age. All participants in the study were healthy male and female adults from Bosnia and Herzegovina, 18–30 years of age. Before sampling, detailed survey and informed consent have been provided by each participant. Comet assay in oral leukocytes and buccal micronucleus cytome (BMCyt) assay in exfoliated buccal cells were applied. Results Almost half of waterpipe smokers (WPS) tasted waterpipe at 15–16 years of age. Comet assay analysis showed increased tail intensity, tail length, and tail moment values among WPS compared to non-smokers (NS) (p = 0.0001, p = 0.0067, and p = 0.0001, respectively). Frequencies of the micronucleated (p = 0.0004), binucleated (p = 0.01), karyorrhectic, (p = 0.0036), and pycnotic cells (p = 0.03) were significantly higher in WPS compared to NS group. Conclusions Genotoxicity and DNA damage biomarkers were increased in oral leukocytes and exfoliated buccal cells of young waterpipe smokers from Bosnia and Herzegovina, compared to NS group.