Search Results (48)

Photodynamic therapy (PDT) has evolved considerably over the past decades, progressing from first-generation porphyrins to second- and third-generation photosensitizers, including nanocarrier-based systems with improved selectivity and bioavailability. In parallel, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) has become a gold standard for the characterisation of complex biomolecules, enabling precise determination of molecular mass, purity and stability. This narrative review explores the intersection of these two fields, focusing on how MALDI-TOF MS supports the development, characterisation and clinical application of photosensitizers used in PDT. Literature searches were performed across PubMed, Web of Science, Scopus and Base-search, followed by targeted retrieval of studies on MALDI and PDT applications. Findings indicate that MALDI-TOF MS plays a crucial role at multiple stages: confirming the synthesis and chemical integrity of novel photosensitizers, monitoring their metabolic stability in biological systems and characterising photodegradation products after PDT. Moreover, MALDI imaging mass spectrometry (MALDI-IMS) enables spatial mapping of photosensitizer distribution in tissues, while rapid pathogen identification by MALDI-TOF supports antimicrobial PDT applications. Collectively, the evidence highlights that MALDI-MS is not only a tool for molecular characterisation but also a versatile analytical platform with a direct translational impact on PDT. Its integration with other omics and multimodal imaging approaches is expected to enhance the personalization and clinical effectiveness of photodynamic therapy. Full article

Biogenic amines (BA) are simple organic bases of low molecular weight, formed during decarboxylation of amino acids. Ripened cheeses provide suitable conditions for the development of bacteria and production of BAs. The aim of the present study was to investigate the presence of eight BAs in ripened cheese samples (n = 125) using a high-performance liquid chromatography with diode array detector (HPLC-DAD). Furthermore, microbiological analyses towards identification of bacteria using matrix-assisted laser desorption ionisation—time of flight mass spectrometry (MALDI-TOF MS) were performed. Cadaverine and putrescine were detected in 28.0% and 20.8% of cheese samples at concentrations ranging from 6.12 to 2871 mg/kg and 5.74 to 441 mg/kg, respectively. High amounts of putrescine and cadaverine in cheeses were associated with the presence of Hafnia alvei. Tyramine was identified in 28.0% of samples in the concentration range of 5.62–646 mg/kg. High concentrations of this amine was found in cheeses containing Enterococcus faecium and Enterococcus faecalis. Histamine content, the only BA restricted in food according to Regulation 2073/2005, was observed above 100 mg/kg in 11.2% of the cheeses. Ripened cheeses available on the local retail market may contain significant levels of biogenic amines and may pose a potential health hazard to consumers. Full article

After virtually disappearing from domestic dwellings in the Western world at the end of the Second World War, bed bugs have re-emerged in recent years. Few studies, however, have been carried out on these insects in tropical islands. In this study, we focussed on describing bed bug specimens collected from dwellings in a high-altitude village in Grande Comore, an island in the Comoros, in the Indian Ocean. We also aimed to detect the bacteria associated with them. Using MALDI-TOF MS coupled with molecular biology, we were able to confirm that the C. hemipterus species (the tropical bug) was the bug infesting these homes. Interestingly, the results also show that MALDI-TOF MS can differentiate between the developmental stages of bed bugs (immature and adult). Screening for bacteria was carried out using qPCR, regular PCR, and sequencing, with only Wolbachia DNA being found. Widespread surveys throughout the country are needed to ascertain the level of bed bug infestation, with a view to implementing appropriate control measures. Full article

Transition metal complexes have been used in medicine for several decades, but their intracellular effects are not yet fully elucidated. Therefore, in this study, we investigate biomolecular changes induced by a palladium(II) complex in cervical carcinoma (HeLa) cells as a model to study the subtle changes caused by transition metal ions ingested by the cells. The impact of dichloro(1,2-diaminocyclohexane)palladium(II), [Pd(dach)Cl₂], was studied by synchrotron radiation-based Fourier transform infrared (SR FTIR) spectroscopy, a powerful tool for studying alterations in cellular components’ biochemical composition and biomolecular secondary structure on a single-cell level. A spectral analysis, complemented by statistics, revealed that the Pd(II) complex considerably affected all major types of macromolecules in HeLa cells and induced structural changes in proteins through an increased formation of cross-β-sheets and causes structural rearrangement in deoxyribonucleic acid (DNA) through potential chromosome fragmentation. Although a certain level of lipid peroxidation was detectable by SR FTIR spectroscopy and confirmed by an analysis of cellular lipids by matrix-assisted laser desorption and ionisation time-of-flight mass spectrometry, the oxidative stress is not a significant mechanism by which Pd(II) expresses the effect on the HeLa cells. Full article

Matrix Assisted Laser Desorption/Ionisation-Mass Spectrometry Imaging (MALDI-MSI) is a well-established spatial omic technique which enables the untargeted mapping of various classes of biomolecules, including tryptic peptides, directly on tissue. This method relies on the use of matrices for the ionisation and volatilisation of analytes, and α-Cyano-4-hydroxycinnamic acid (CHCA) represents the most widespread matrix for tryptic peptides analysis. However, CHCA also presents certain limitations that foster the quest for novel matrix compounds. 6-aza-2-thiothymine (ATT), traditionally used in MALDI mass spectrometry (MS) for oligonucleotides, small molecules and oxidised phospholipids, has not been thoroughly investigated as a potential matrix for tryptic peptide analysis in MALDI-MS or MALDI-MSI. Therefore, this study addresses this gap by evaluating the capability of ATT to ionise tryptic peptides from Bovine Serum Albumin (BSA) and map in situ-digested peptides from formalin-fixed paraffin-embedded (FFPE) tissue sections in these respective applications. Comparative analysis with CHCA demonstrated the complementary strengths of these matrices for detecting tryptic peptides, establishing ATT as a feasible alternative to CHCA in the MALDI-MSI field and paving the way for future advancements in spatial proteomics. Full article

The aim of the study was to assess the bacterial flora of broiler chicken breast meat using the MALDI method, as well as its sensory evaluation while stored refrigerated at a stable temperature (0.5 °C+/−0.5 °C). Bacterial identification based on peptidic spectra obtained by matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF MS) mass spectrometry is a rapid, inexpensive, and accurate method for identifying isolates that belong to certain bacterial phyla. The microbiological and sensory quality was assessed on the 1st and 3rd, 5th, 7th, 8th, 9th, 10th, 11th, and 12th day of refrigerated storage. The study identified psychrophilic bacteria to be the dominant microflora during the entire period of refrigerated storage. The species profile of the bacteria, however, varied in the subsequent days of storage. From the 8th day of storage, the profile was dominated by bacteria of the genus Pseudomonas. The proportionate content of Pseudomonas bacteria ranged from 89% on day 8 to 95% on day 11th of storage. The majority of the unfavourable microflora (Aeromonas species, Alcaligenes spp., Klebsiella spp., and Yersinia spp.) were observed on the 11th day of storage, which indicates that meat spoilage processes had commenced. The quality of breast meat from broiler chickens stored at 0.5 °C+/−0.5 °C was sensorially acceptable up to the 8th day of storage. Full article

We investigated the use of boron-doped diamond (BDD) with different surface morphologies for the enhanced detection of nine different peptides by matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS). For the first time, we compared three different nanostructured BDD film morphologies (Continuous, Nanograss, and Nanotips) with differently terminated surfaces (-H, -O, and -F) to commercially available Ground Steel plates. All these surfaces were evaluated for their effectiveness in detecting the nine different peptides by MALDI-MS. Our results demonstrated that certain nanostructured BDD surfaces exhibited superior performance for the detection of especially hydrophobic peptides (e.g., bradykinin 1–7, substance P, and the renin substrate), with a limit of detection of down to 2.3 pM. Further investigation showed that hydrophobic peptides (e.g., bradykinin 1–7, substance P, and the renin substrate) were effectively detected on hydrogen-terminated BDD surfaces. On the other hand, the highly acidic negatively charged peptide adrenocorticotropic hormone fragment 18–39 was effectively identified on oxygen-/fluorine-terminated BDD surfaces. Furthermore, BDD surfaces reduced sodium adduct contamination significantly. Full article

Breast cancer, a complex disease with a significant prevalence to form metastases, necessitates novel therapeutic strategies to improve treatment outcomes. Here, we present the results of a comparative molecular study of primary breast tumours, their metastases, and the corresponding primary cell lines using Desorption Electrospray Ionisation (DESI) and Laser-Assisted Rapid Evaporative Ionisation Mass Spectrometry (LA-REIMS) imaging. Our results show that ambient ionisation mass spectrometry technology is suitable for rapid characterisation of samples, providing a lipid- and metabolite-rich spectrum within seconds. Our study demonstrates that the lipidomic fingerprint of the primary tumour is not significantly distinguishable from that of its metastasis, in parallel with the similarity observed between their respective primary cell lines. While significant differences were observed between tumours and the corresponding cell lines, distinct lipidomic signatures and several phospholipids such as PA(36:2), PE(36:1), and PE(P-38:4)/PE(O-38:5) for LA-REIMS imaging and PE(P-38:4)/PE(O-38:5), PS(36:1), and PI(38:4) for DESI-MSI were identified in both tumours and cells. We show that the tumours’ characteristics can be found in the corresponding primary cell lines, offering a promising avenue for assessing tumour responsiveness to therapeutic interventions. A comparative analysis by DESI-MSI and LA-REIMS imaging revealed complementary information, demonstrating the utility of LA-REIMS in the molecular imaging of cancer. Full article

A multimodal mass spectrometry imaging (MSI) approach was used to investigate the chemotherapy drug-induced response of a Multicellular Tumour Spheroid (MCTS) 3D cell culture model of osteosarcoma (OS). The work addresses the critical demand for enhanced translatable early drug discovery approaches by demonstrating a robust spatially resolved molecular distribution analysis in tumour models following chemotherapeutic intervention. Advanced high-resolution techniques were employed, including desorption electrospray ionisation (DESI) mass spectrometry imaging (MSI), to assess the interplay between metabolic and cellular pathways in response to chemotherapeutic intervention. Endogenous metabolite distributions of the human OS tumour models were complemented with subcellularly resolved protein localisation by the detection of metal-tagged antibodies using Imaging Mass Cytometry (IMC). The first application of matrix-assisted laser desorption ionization–immunohistochemistry (MALDI-IHC) of 3D cell culture models is reported here. Protein localisation and expression following an acute dosage of the chemotherapy drug doxorubicin demonstrated novel indications for mechanisms of region-specific tumour survival and cell-cycle-specific drug-induced responses. Previously unknown doxorubicin-induced metabolite upregulation was revealed by DESI-MSI of MCTSs, which may be used to inform mechanisms of chemotherapeutic resistance. The demonstration of specific tumour survival mechanisms that are characteristic of those reported for in vivo tumours has underscored the increasing value of this approach as a tool to investigate drug resistance. Full article

Canine osteosarcoma (OSA) is an aggressive bone neoplasia with high metastatic potential. Metastasis is the main cause of death associated with OSA, and there is no current treatment available for metastatic disease. Proteomic analyses, including matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI TOF/TOF MS), are widely used to select molecular targets and identify proteins that may play a key role in primary tumours and at various steps of the metastatic cascade. The main aim of this study was to identify proteins differently expressed in canine OSA cell lines with different malignancy phenotypes (OSCA-8 and OSCA-32) compared to canine osteoblasts (CnOb). The intermediate aim of the study was to compare canine OSA cell migration capacity and assess its correlation with the malignancy phenotypes of each cell line. Using MALDI-TOF/TOF MS analyses, we identified eight proteins that were significantly differentially expressed (p ≤ 0.05) in canine OSA cell lines compared to CnOb: cilia- and flagella-associated protein 298 (CFAP298), general transcription factor II-I (GTF2I), mirror-image polydactyly gene 1 protein (MIPOL1), alpha-2 macroglobulin (A2M), phosphoglycerate mutase 1 (PGAM1), ubiquitin (UB2L6), ectodysplasin-A receptor-associated adapter protein (EDARADD), and leucine-rich-repeat-containing protein 72 (LRRC72). Using the Simple Western technique, we confirmed high A2M expression in CnOb compared to OSCA-8 and OSCA-32 cell lines (with intermediate and low A2M expression, respectively). Then, we confirmed the role of A2M in cancer cell migration by demonstrating significantly inhibited OSA cell migration by treatment with A2M (both at 10 and 30 mM concentrations after 12 and 24 h) in a wound-healing assay. This study may be the first report indicating A2M’s role in OSA cell metastasis; however, further in vitro and in vivo studies are needed to confirm its possible role as an anti-metastatic agent in this malignancy. Full article

Bioactive peptides (BPs) are molecules of paramount importance with great potential for the development of functional foods, nutraceuticals or therapeutics for the prevention or treatment of various diseases. A functional BP-rich dairy product was produced by lyophilisation of bovine milk fermented by the autochthonous strains Lactococcus lactis subsp. lactis ZGBP5-51, Enterococcus faecium ZGBP5-52 and Enterococcus faecalis ZGBP5-53 isolated from the same artisanal fresh cheese. The efficiency of the proteolytic system of the implemented strains in the production of BPs was confirmed by a combined high-throughput mass spectrometry (MS)-based peptidome profiling and an in silico approach. First, peptides released by microbial fermentation were identified via a non-targeted peptide analysis (NTA) comprising reversed-phase nano-liquid chromatography (RP nano-LC) coupled with matrix-assisted laser desorption/ionisation-time-of-flight/time-of-flight (MALDI-TOF/TOF) MS, and then quantified by targeted peptide analysis (TA) involving RP ultrahigh-performance LC (RP-UHPLC) coupled with triple-quadrupole MS (QQQ-MS). A combined database and literature search revealed that 10 of the 25 peptides identified in this work have bioactive properties described in the literature. Finally, by combining the output of MS-based peptidome profiling with in silico bioactivity prediction tools, three peptides (⁷⁵QFLPYPYYAKPA⁸⁶, ⁴⁰VAPFPEVFGK⁴⁹, ¹¹⁷ARHPHPHLSF¹²⁶), whose bioactive properties have not been previously reported in the literature, were identified as potential BP candidates. Full article

The purpose of this study was to evaluate the effect of temperature (2 °C and 6 °C) and storage duration on the quality and attributes of hens’ breast meat after their laying periods. The study included physicochemical characteristics (pH, drip loss, colour, shear force), microbiological quality (total Enterobacteriaceae family and Pseudomonas count), and sensory quality. Bacterial identification was performed using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. The increased meat pH and drip loss was greater at 6 than 2 °C (p < 0.05). An increase in the tenderness of the meat stored at 6 °C was found as early as day 4, as well as at 2 °C on day 8 of storage (p < 0.05). On day 4 of storage, the meat was characterised by a darker colour than on the first day, but the darkening was greater at 6 °C than at 2 °C (p < 0.05). At 6 °C, on day 4 of storage, there was an increase in yellow saturation (b*) of the meat, which was higher at 6 °C than at 2 °C (p < 0.05). At 2 °C, the total bacterial count and number of Pseudomonas spp. in the meat gradually increased along with increasing storage duration, reaching 4.64 log cfu/g and 4.48 log cfu/g, respectively, on the 8th day of storage. At 6 °C, on the sixth day of storage, the total bacterial count in the meat exceeded 7 log cfu/g, considered the limit of microbiological safety. The meat stored at 2 °C had an acceptable sensory quality until the 8th day of storage. The study shows that storage at 2 °C preserves the sensory characteristics and microbiological safety of the hen meat longer at an acceptable level after the laying period. Extended storage life may be of importance to consumers and the meat industry. Full article

The Gram-negative bacterium Gallibacterium anatis is part of the normal avian respiratory, intestinal and reproductive tract microflora and can be transmitted horizontally and vertically. With the coexistence of other relevant factors, G. anatis becomes an opportunistic pathogen, economically damaging to the poultry industry. This bacterium’s prevalence and molecular epidemiology were investigated, and the antimicrobial treatment options for G. anatis infection in chicken flocks in Poland were assessed. Tracheal samples from 182 flocks were collected between April 2022 and March 2023. The bacterial prevalence was determined by PCR targeting the gyrB gene and 16–23S rRNA. Gallibacterium anatis was identified by matrix-assisted laser desorption/ionisation–time-of-flight mass spectrometry (MALDI-TOF) after culturing and PCR amplification. Isolates’ susceptibility to 11 antimicrobials was assessed with a disc diffusion test. Isolates were also tested for gyrB, GtxA and flfA virulence genes and bla_ROB, aphA, tetB and tetH antibiotic resistance genes by PCR. Forty-one flocks (22.5%) were positive through PCR. Antibiotic resistance was most frequently observed against tilmicosin, tylosin, enrofloxacin, amoxicillin, tetracycline and doxycycline. Multiple resistance to at least eight antibiotics occurred in 20% of isolates and to at least four in 100%. The occurrence of gyrB was noted in 100%, GtxA was detected in 89%, and flfA was found in 14% of positive samples. The tetB gene was present in 61.0% of positive samples, tetH was in 36.0%, aphA was in 16.7%, and bla_ROB was in 5.6%. Significant differences were found in G. anatis isolates related to the presence of the virulence genes GtxA and gyrB and the presence of resistance genes (p < 0.05) associated with resistance to tetracyclines, β-lactams and aminoglycosides. The continued rise in the resistance of G. anatis to a broadening range of antibiotics is a major problem for the poultry industry worldwide, as well as for public health. The findings of this study may expand the knowledge of the pathogenicity of G. anatis in poultry. Full article

We investigated whether a high-fat/high-sugar (HF/HS) diet alters the lipidomic profile of the oviductal epithelium (OE) and studied the patterns of these changes over time. Female outbred Swiss mice were fed either a control (10% fat) or HF/HS (60% fat, 20% fructose) diet. Mice (n = 3 per treatment per time point) were sacrificed and oviducts were collected at 3 days and 1, 4, 8, 12 and 16 weeks on the diet. Lipids in the OE were imaged using matrix-assisted laser desorption ionisation mass spectrometry imaging. Discriminative m/z values and differentially regulated lipids were determined in the HF/HS versus control OEs at each time point. Feeding the obesogenic diet resulted in acute changes in the lipid profile in the OE already after 3 days, and thus even before the development of an obese phenotype. The changes in the lipid profile of the OE progressively increased and became more persistent after long-term HF/HS diet feeding. Functional annotation revealed a differential abundance of phospholipids, sphingomyelins and lysophospholipids in particular. These alterations appear to be not only caused by the direct accumulation of the excess circulating dietary fat but also a reduction in the de novo synthesis of several lipid classes, due to oxidative stress and endoplasmic reticulum dysfunction. The described diet-induced lipidomic changes suggest alterations in the OE functions and the oviductal microenvironment which may impact crucial reproductive events that take place in the oviduct, such as fertilization and early embryo development. Full article

Questioned document examination aims to assess if a document of interest has been forged. Spectroscopy-based methods are the gold standard for this type of evaluation. In the past 15 years, Matrix-Assisted Laser Desorption Ionisation–Mass Spectrometry Imaging (MALDI-MSI) has emerged as a powerful analytical tool for the examination of finger marks, blood, and hair. Therefore, this study intended to explore the possibility of expanding the forensic versatility of this technique through its application to questioned documents. Specifically, a combination of MALDI-MSI and chemometric approaches was investigated for the differentiation of seven gel pens, through their ink composition, over 44 days to assess: (i) the ability of MALDI MSI to detect and image ink chemical composition and (ii) the robustness of the combined approach for the classification of different pens over time. The training data were modelled using elastic net logistic regression to obtain probabilities for each pen class and assess the time effect on the ink. This strategy led the classification model to yield predictions matching the ground truth. This model was validated using signatures generated by different pens (blind to the analyst), yielding a 100% accuracy in machine learning cross-validation. These data indicate that the coupling of MALDI-MSI with machine learning was robust for ink discrimination within the dataset and conditions investigated, which justifies further studies, including that of confounders such as paper brands and environmental factors. Full article