Chemotherapeutic response to cisplatin-like drugs in human breast cancer cells probed by vibrational microspectroscopy

Vibrational microspectroscopy as a tool to unveil new chemotherapeutic strategies against osteosarcoma

Over the years, osteosarcoma therapy has had a significative improvement with the use of a multidrug regime strategy, increasing the survival rates from less than 20 % to circa 70 %. Different types of development of new antineoplastic agents are critical to achieve irreversible damage to cancer cells, while preserving the integrity of their healthy counterparts. In the present study, complexes with two and three Pd(II) centres linked by the biogenic polyamines: spermine (Pd2SpmCl4) and spermidine (Pd3Spd2Cl6) were tested against non-malignant (osteoblasts, HOb) and cancer (osteosarcoma, MG-63) human cell lines. Either alone or in combination according to the EURAMOS-1 protocol, they were used versus cisplatin as a drug reference. By evaluating the cytotoxic effects of both therapeutic approaches (single and drug combination) in HOb and MG-63 cell lines, the selective anti-tumoral potential is assessed. To understand the different treatments at a molecular level, Synchrotron Radiation Fourier Transform Infrared and Raman microspectroscopies were applied. Principal component analysis and hierarchical cluster analysis are applied to the vibrational data, revealing the major metabolic changes caused by each drug, which were found to rely on DNA, lipids, and proteins, acting as biomarkers of drug-to-cell impact. The main changes were observed for the B-DNA native conformation to either Z-DNA (higher in the presence of polynuclear complexes) or A-DNA (preferably after cisplatin exposure). Additionally, a higher effect upon variation in proteins content was detected in drug combination when compared to single drug administration proving the efficacy of the EURAMOS-1 protocol with the new drugs tested.

Cervical Squamous Cell Carcinoma Diagnosis by FTIR Microspectroscopy

Cervical cancer was considered the fourth most common cancer worldwide in 2020. In order to reduce mortality, an early diagnosis of the tumor is required. Currently, this type of cancer occurs mostly in developing countries due to the lack of vaccination and screening against the Human Papillomavirus. Thus, there is an urgent clinical need for new methods aiming at a reliable screening and an early diagnosis of precancerous and cancerous cervical lesions. Vibrational spectroscopy has provided very good results regarding the diagnosis of various tumors, particularly using Fourier transform infrared microspectroscopy, which has proved to be a promising complement to the currently used histopathological methods of cancer diagnosis. This spectroscopic technique was applied to the analysis of cryopreserved human cervical tissue samples, both squamous cell carcinoma (SCC) and non-cancer samples. A dedicated Support Vector Machine classification model was constructed in order to categorize the samples into either normal or malignant and was subsequently validated by cross-validation, with an accuracy higher than 90%.

Cellular dynamics as a marker of normal-to-cancer transition in human cells

Normal-to-cancer (NTC) transition is known to be closely associated to cell´s biomechanical properties which are dependent on the dynamics of the intracellular medium. This study probes different human cancer cells (breast, prostate and lung), concomitantly to their healthy counterparts, aiming at characterising the dynamical profile of water in distinct cellular locations, for each type of cell, and how it changes between normal and cancer states. An increased plasticity of the cytomatrix is observed upon normal-to-malignant transformation, the lung carcinoma cells displaying the highest flexibility followed by prostate and breast cancers. Also, lung cells show a distinct behaviour relative to breast and prostate, with a higher influence from hydration water motions and localised fast rotations upon NTC transformation. Quasielastic neutron scattering techniques allowed to accurately distinguish the different dynamical processes taking place within these highly heterogeneous cellular systems. The results thus obtained suggest that intracellular water dynamics may be regarded as a specific reporter of the cellular conditions-either healthy or malignant.

Quantitative Raman chemical imaging of intracellular drug-membrane aggregates and small molecule drug precipitates in cytoplasmic organelles

Raman confocal microscopes have been used to visualize the distribution of small molecule drugs within different subcellular compartments. This visualization allows the discovery, characterization, and detailed analysis of the molecular transport phenomena underpinning the Volume of Distribution - a key parameter governing the systemic pharmacokinetics of small molecule drugs. In the specific case of lipophilic small molecules with large Volumes of Distribution, chemical imaging studies using Raman confocal microscopes have revealed how weakly basic, poorly soluble drug molecules can accumulate inside cells by forming stable, supramolecular complexes in association with cytoplasmic membranes or by precipitating out within organelles. To study the self-assembly and function of the resulting intracellular drug inclusions, Raman chemical imaging methods have been developed to measure and map the mass, concentration, and ionization state of drug molecules at a microscopic, subcellular level. Beyond the field of drug delivery, Raman chemical imaging techniques relevant to the study of microscopic drug precipitates and drug-lipid complexes which form inside cells are also being developed by researchers with seemingly unrelated scientific interests. Highlighting advances in data acquisition, calibration methods, and computational data management and analysis tools, this review will cover a decade of technological developments that enable the conversion of spectral signals obtained from Raman confocal microscopes into new discoveries and information about previously unknown, concentrative drug transport pathways driven by soluble-to-insoluble phase transitions occurring within the cytoplasmic organelles of eukaryotic cells.

Sub-Cellular Dynamic Analysis of BGC823 Cells after Treatment with the Multi-Component Drug CKI Using Raman Spectroscopy

Multi-component drugs (MCDs) can induce various cellular changes covering multiple levels, from molecular and subcellular structure to cell morphology. A "non-invasive" method for comprehensively detecting the dynamic changes of cellular fine structure and chemical components on the subcellular level is highly desirable for MCD studies. In this study, the subcellular dynamic processes of gastric cancer BGC823 cells after treatment with a multi-component drug, Compound Kushen Injection (CKI), were investigated using a homemade, high-resolution, confocal Raman spectroscopy (RS) device combined with bright-field imaging. The Raman spectra of the nucleus, cytoplasm and intracellular vesicles (0.4-1 μm) were collected simultaneously for each cell treated with CKI at different times and doses. The RS measurements showed that CKI decreased the DNA signatures, which the drug is known to inhibit. Meanwhile, the CKI-induced subcellular dynamic changes in the appearance of numerous intracellular vesicles and the deconstruction of cytoplasm components were observed and discussed. The results demonstrated that high-resolution subcellular micro-Raman spectroscopy has potential for detecting fine cellular dynamic variation induced by drugs and the screening of MCDs in cancer therapy.

Assessing B-Z DNA Transitions in Solutions via Infrared Spectroscopy

Z-DNA refers to the left-handed double-helix DNA that has attracted much attention because of its association with some specific biological functions. However, because of its low content and unstable conformation, Z-DNA is normally difficult to observe or identify. Up to now, there has been a lack of unified or standard analytical methods among diverse techniques for probing Z-DNA and its transformation conveniently. In this work, NaCl, MgCl₂, and ethanol were utilized to induce d(GC)₈ from B-DNA to Z-DNA in vitro, and Fourier transform infrared (FTIR) spectroscopy was employed to monitor the transformation of Z-DNA under different induction conditions. The structural changes during the transformation process were carefully examined, and the DNA chirality alterations were validated by the circular dichroism (CD) measurements. The Z-DNA characteristic signals in the 1450 cm^-1-900 cm^-1 region of the d(GC)₈ infrared (IR) spectrum were observed, which include the peaks at 1320 cm^-1, 1125 cm^-1 and 925 cm^-1, respectively. The intensity ratios of A₁₃₂₀/A₉₇₀, A₁₁₂₅/A₉₇₀, and A₉₂₅/A₉₇₀ increased with Z-DNA content in the transition process. Furthermore, compared with the CD spectra, the IR spectra showed higher sensitivity to Z-DNA, providing more information about the molecular structure change of DNA. Therefore, this study has established a more reliable FTIR analytical approach to assess BZ DNA conformational changes in solutions, which may help the understanding of the Z-DNA transition mechanism and promote the study of Z-DNA functions in biological systems.

Spectrochemical analysis of seasonal and sexual variation of antioxidants in Corema album (L.) D. Don leaf extracts

Bioactive phytoconstituents have been increasingly investigated for their potential human health benefits. Corema album (L.) D. Don, an Ericaceae, reportedly has antioxidant, antimicrobial and anticancer properties. Aiming at enhancing its nutraceutical potential, we performed a spectrochemical analysis of hydroethanolic extracts from C. album leaves. We report on changes in the antioxidant activity of the extracts, as well as in the accumulation of key phytoconstituents (namely phenolic compounds), in female and male samples, throughout three harvesting seasons (February, July, and October). For each extract, the antioxidant activity was assessed by different spectrophotometric methods. Simultaneously, attenuated total reflectance Fourier transform mid-infrared spectroscopy (FTIR-ATR), and high-performance liquid chromatography - electrospray ionisation - quadrupole time-of-flight mass spectrometry (HPLC-ESI-Q-TOF-MS), were used to identify and monitor variations in the composition of phenolic compounds in the extracts. The main compounds identified were epicatechin, laricitrin-O-hexoside isomers, and myricetin-O-hexoside isomers. Significant differences were found in the composition and relative abundance of the compounds of interest, according to sex and season. Overall, a trend was observed whereby phenolic content and antioxidant activities were higher in males and increased between the earlier and the latest harvests. Based on these results, we may conclude that late summer or early autumn harvests are preferable when aiming at the highest yearly content of bioactive compounds. Additionally, it should be considered that extracts from male individuals typically display higher antioxidant activities. Ultimately, our understanding of C. album in the context of nutraceutical applications is benefited from the quantitative and qualitative portrait provided here, thus promoting its relevance as a source of bioactive compounds.

A Non-Conventional Platinum Drug against a Non-Small Cell Lung Cancer Line

A dinuclear Pt(II) complex with putrescine as bridging polyamine ligand ([Pt₂Put₂(NH₃)₄]Cl₄) was synthesized and assessed as to its potential anticancer activity against a human non-small cell lung cancer line (A549), as well as towards non-cancer cells (BEAS-2B). This effect was evaluated through in vitro cytotoxicity assays (MTT and SRB) coupled to microFTIR and microRaman spectroscopies, the former delivering information on growth-inhibiting and cytotoxic abilities while the latter provided very specific information on the metabolic impact of the metal agent (at the sub-cellular level). Regarding cancer cells, a major impact of [Pt₂Put₂(NH₃)₄]Cl₄ was evidenced on cellular proteins and lipids, as compared to DNA, particularly via the Amide I and Amide II signals. The effect of the chelate on non-malignant cells was lower than on malignant ones, evidencing a promising low toxicity towards healthy cells.

Effect of Cisplatin and Its Cationic Analogues in the Phase Behavior and Permeability of Model Lipid Bilayers

Increasing evidence suggests a critical role of lipids in both the mechanisms of toxicity and resistance of cells to platinum(II) complexes. In particular, cisplatin and other analogues were reported to interact with lipids and transiently promote lipid phase changes both in the bulk membranes and in specific membrane domains. However, these processes are complex and not fully understood. In this work, cisplatin and its cationic species formed at pH 7.4 in low chloride concentrations were tested for their ability to induce phase changes in model membranes with different lipid compositions. Fluorescent probes that partition to different lipid phases were used to report on the fluidity of the membrane, and a leakage assay was performed to evaluate the effect of cisplatin in the permeability of these vesicles. The results showed that platinum(II) complex effects on membrane fluidity depend on membrane lipid composition and properties, promoting a stronger decrease in the fluidity of membranes containing gel phase. Moreover, at high concentration, these complexes were prone to alter the permeability of lipid membranes without inducing their collapse or aggregation.

Evaluation of the Cytotoxic Effect of Pd2Spm against Prostate Cancer through Vibrational Microspectroscopies

Regarding the development of new antineoplastic agents, with a view to assess the selective antitumoral potential which aims at causing irreversible damage to cancer cells while preserving the integrity of their healthy counterparts, it is essential to evaluate the cytotoxic effects in both healthy and malignant human cell lines. In this study, a complex with two Pd(II) centers linked by the biogenic polyamine spermine (Pd₂Spm) was tested on healthy (PNT-2) and cancer (LNCaP and PC-3) prostate human cell lines, using cisplatin as a reference. To understand the mechanisms of action of both cisplatin and Pd₂Spm at a molecular level, Fourier Transform Infrared (FTIR) and Raman microspectroscopies were used. Principal component analysis was applied to the vibrational data, revealing the major metabolic changes caused by each drug, which were found to rely on DNA, lipids, and proteins, acting as biomarkers of drug impact. The main changes were observed between the B-DNA native conformation and either Z-DNA or A-DNA, with a higher effect on lipids having been detected in the presence of cisplatin as compared to Pd₂Spm. In turn, the Pd-agent showed a more significant impact on proteins.

Synchrotron radiation-based Fourier transform infrared microspectroscopy investigation of WRL68 cells treated with doxorubicin

Doxorubicin is an effective chemotherapeutic agent applied in a wide variety of cancers. Despite its potent anticancer activity towards cancer cells, doxorubicin is also toxic to noncancerous cells. Therefore, doxorubicin can cause serious side effects in various organs, especially when dose escalation is required for patients with advanced disease. The liver is the major detoxification organ that metabolizes drugs, and hepatotoxicity is one of the most common adverse effects of doxorubicin administration. However, the exact mechanisms of doxorubicin-induced hepatotoxicity have not been clearly identified, and how doxorubicin treatment affects the biomolecular contents of normal human hepatocytes has rarely been studied. Synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy is a state-of-the-art analytical technique for characterizing the biomolecules present in cells. In this research, the biomolecular alterations of doxorubicin-treated normal human hepatocytes compared to untreated control cells were investigated at the single-cell level by combining SR-FTIR microspectroscopy with the Cell Counting Kit-8 (CCK-8) assay and flow cytometry. WRL68 human normal embryonic liver cells, which have been shown to be very promising for assessing the cytotoxicity of toxic compounds and investigating hepato-toxicology, were used in this research. Principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) were used to further analyse the biomolecular contents of WRL68 cells. The order of lipid acyl chains and protein α-helix structures in doxorubicin-treated WRL68 cells was found to be distinctly changed, while the nucleic acids were altered relatively less. No alteration in the carbohydrate content was distinguishable after doxorubicin treatment. These results provide more comprehensive information about the biomolecular changes in hepatocytes induced by doxorubicin treatment and help to elucidate the mechanism of doxorubicin-induced hepatotoxicity. This research also proves that SR-FTIR microspectroscopy, combined with PCA and OPLS-DA, is a promising approach for investigating drug-cell interaction systems.

Microscopic Raman illustrating antitumor enhancement effects by the combination drugs of γ-secretase inhibitor and cisplatin on osteosarcoma cells

By using Raman microspectroscopy, it aims to elucidate the cellular variations caused by the combination drug of γ-secretase inhibitor (DAPT) and cisplatin in osteosarcoma (OS) cells. Illustrated by the obtained results of spectral analysis, the intracellular composition significantly changed after combined drug actions compared to the solo DAPT treatment, indicating the synergistic effect of DAPT combined with cisplatin on OS cells. Meanwhile, multivariate curve resolution-alternating least squares (MCR-ALS) algorithm was utilized to address the biochemical constitution changes in all investigated groups including the untreated (UT), DAPT (40D) and combined drug (40D + 20C) treated cells. K-means cluster and univariate imaging were both utilized to visualize the changes in subcellular morphology and biochemical distribution. The presented study provides a unique understanding on the cellular responses to DAPT combined with cisplatin from the natural biochemical perspectives, and laids an experimental foundation for exploring the therapeutic strategies of other combined anticancer drugs in cancer cell model.

Effect of Pd2Spermine on Mice Brain-Liver Axis Metabolism Assessed by NMR Metabolomics

Cisplatin (cDDP)-based chemotherapy is often limited by severe deleterious effects (nephrotoxicity, hepatotoxicity and neurotoxicity). The polynuclear palladium(II) compound Pd₂Spermine (Pd₂Spm) has emerged as a potential alternative drug, with favorable pharmacokinetic/pharmacodynamic properties. This paper reports on a Nuclear Magnetic Resonance metabolomics study to (i) characterize the response of mice brain and liver to Pd₂Spm, compared to cDDP, and (ii) correlate brain-liver metabolic variations. Multivariate and correlation analysis of the spectra of polar and lipophilic brain and liver extracts from an MDA-MB-231 cell-derived mouse model revealed a stronger impact of Pd₂Spm on brain metabolome, compared to cDDP. This was expressed by changes in amino acids, inosine, cholate, pantothenate, fatty acids, phospholipids, among other compounds. Liver was less affected than brain, with cDDP inducing more metabolite changes. Results suggest that neither drug induces neuronal damage or inflammation, and that Pd₂Spm seems to lead to enhanced brain anti-inflammatory and antioxidant mechanisms, regulation of brain bioactive metabolite pools and adaptability of cell membrane characteristics. The cDDP appears to induce higher extension of liver damage and an enhanced need for liver regeneration processes. This work demonstrates the usefulness of untargeted metabolomics in evaluating drug impact on multiple organs, while confirming Pd₂Spm as a promising replacement of cDDP.

An electrochemical membrane-based aptasensor for detection of severe acute respiratory syndrome coronavirus-2 receptor-binding domain

Herein, we report an electrochemical membrane-based aptasensor for the determination of the SARS-CoV-2 receptor-binding domain (SARS-CoV-2-RBD). For this purpose, the nanoporous anodic aluminium oxide membrane (NPAOM) was first fabricated electrochemically. The NPAOM was then functionalized with 3-mercaptopropyl trimethoxysilane (NPAOM-Si-SH). After that, the NPAOM-Si-SH was decorated with gold nanoparticles by using gold ion and sodium borohydride. The NPAOM-Si-S-Au_nano was then attached to the surface of the working electrode of a laser-engraved graphene electrode (LEGE). Subsequently, the LEGE/NPAOM-Si-S-Au_nano was fixed inside a flow cell that was made by using a three-dimensional (3D) printer, and then thiolated aptamer was transferred into the flow cell using a pump. The electrochemical behavior of the LEGE/NPAOM-Si-S-Au_nano-Aptamer was studied using square wave voltammetry (SWV) in the presence of potassium ferrocyanide as a redox probe. The response of the LEGE/NPAOM-Si-S-Au_nano-Aptamer to the different concentrations of the SARS-CoV-2-RBD in human saliva sample was investigated in the concentration range of 2.5-40.0 ng/mL. The limit of the detection was found to be 0.8 ng/mL. The LEGE/NPAOM-Si-S-Au_nano-Aptamer showed good selectivity to 5.0 ng/mL of SARS-CoV-2-RBD in the presence of five times of the interfering agents like hemagglutinin and neuraminidase as the influenza A virus major surface glycoproteins.

Cancer Stem Cell Derived Extracellular Vesicles with Self-Functionalized 3D Nanosensor for Real-Time Cancer Diagnosis: Eliminating the Roadblocks in Liquid Biopsy

Liquid biopsy for determining the presence of cancer and the underlying tissue of origin is crucial to overcome the limitations of existing tissue biopsy and imaging-based techniques by capturing critical information from the dynamic tumor heterogeneity. A newly emerging liquid biopsy with extracellular vesicles (EVs) is gaining momentum, but its clinical relevance is in question due to the biological and technical challenges posed by existing technologies. The biological barriers of existing technologies include the inability to generate fundamental details of molecular structure, chemical composition as well as functional variations in EVs by gathering simultaneous information on multiple intra-EV molecules, unavailability of holistic qualitative analysis, in addition to the inability to identify tissue of origin. Technological barriers include reliance on EV isolation with a few labeled biomarkers, resulting in the inability to generate comprehensive information on the disease. A more favorable approach would be to generate holistic information on the disease without the use of labels. Such a marker-free diagnosis is impossible with the existing liquid biopsy due to the unavailability clinically validated cancer stem cells (CSC)-specific markers and dependence of existing technologies on EV isolation, undermining the clinical relevance of EV-based liquid biopsy. Here, CSC EVs were employed as an independent liquid biopsy modality. We hypothesize that tracking the signals of CSCs in peripheral blood with CSC EVs will provide a reliable solution for accurate cancer diagnosis, as CSC are the originators of tumor contributing to tumor heterogeneity. We report nanoengineered 3D sensors of extremely small nano-scaled probes self-functionalized for SERS, enabling integrative molecular and functional profiling of otherwise undetectable CSC EVs. A substantially enhanced SERS and ultralow limit of detection (10 EVs per 10 μL) were achieved. This was attributed to the efficient probe-EV interaction due to the 3D networks of nanoprobes, ensuring simultaneous detection of multiple EV signals. We experimentally demonstrate the crucial role of CSC EVs in cancer diagnosis. We then completed a pilot validation of this modality for cancer detection as well as for identification of the tissue of origin. An artificial neural network distinguished cancer from noncancer with 100% sensitivity and 100% specificity for three hard to detect cancers (breast, lung, and colorectal cancer). Binary classification to distinguish one tissue of origin against all other achieved 100% accuracy, while simultaneous identification of all three tissues of origin with multiclass classification achieved up to 79% accuracy. This noninvasive tool may complement existing cancer diagnostics, treatment monitoring as well as longitudinal disease monitoring by validation with a large cohort of clinical samples.

Water dynamics in human cancer and non-cancer tissues

Normal-to-malignant transformation is a poorly understood process associated with cellular biomechanical properties. These are strongly dependent on the dynamical behaviour of water, known to play a fundamental role in normal cellular activity and in the maintenance of the three-dimensional architecture of the tissue and the functional state of biopolymers. In this study, quasi-elastic neutron scattering was used to probe the dynamical behaviour of water in human cancer specimens and their respective surrounding normal tissue from breast and tongue, as an innovative approach for identifying particular features of malignancy. This methodology has been successfully used by the authors in human cells and was the first study of human tissues by neutron scattering techniques. A larger flexibility was observed for breast versus tongue tissues. Additionally, different dynamics were found for malignant and non-malignant specimens, depending on the tissue: higher plasticity for breast invasive cancer versus the normal, and an opposite effect for tongue. The data were interpreted in the light of two different water populations within the samples: one displaying bulk-like dynamics (extracellular and intracellular/cytoplasmic) and another with constrained flexibility (extracellular/interstitial and intracellular/hydration layers).

Tracking the Evolution of Metastasis with Self-Functionalized 3D Nanoprobes

Despite recent advances in cancer treatment, metastasis is the cause of mortality in 90% of cancer cases. It has now been well-established that dissemination of cancer cells to distant sites occurs very early during tumorigenesis, resulting in the minimal effect of surgical or chemotherapeutic treatments after the detection of metastasis. The underlying reason for this challenge is mostly due to the limited understanding of molecular mechanisms of the metastasis cascade, particularly related to metastatic traits. Therefore, there is an urgent need to investigate this currently invisible evolution of metastasis. The tracking of metastasis evolution has not been addressed yet. Here, we introduce, for the first time, a synchronous approach to unveil the molecular mechanisms of the metastasis cascade. As cancer stem cells (CSCs) demonstrate cancer initiation, drug resistance, metastasis, and tumor relapse and can exist in a quasi-intermediate epithelial-mesenchymal transition state, the tumor-initiating events during a CSCs metamorphosis were monitored with single-cell sensitivity. Because of the invasive and resistive properties of the metastable intermediate CSCs, investigation of the molecular profiles of the quasi-intermediate CSCs was necessary for the detection of metastasis dissemination. For this purpose, the ultrasensitive technique of surface-enhanced Raman scattering (SERS) was adopted. Titanium-based, biocompatible three-dimensional (3D) nanoprobes that were synthesized for multiphoton ionization achieved a substantial SERS enhancement of ∼80-fold due to the oxygen vacancy-enriched composition of the nanoprobes. The 3D interconnected complex nanoarchitecture of the nanoprobes enabled us to entrap the nonadherent CSCs of three metastatic cancer cell lines (triple negative breast adenocarcinoma (MDAMB231), human Caucasian colon adenocarcinoma (COLO 205), and cervical adenocarcinoma (HeLa)─all very aggressive forms of cancer). The nanoprobes not only promoted the CSC proliferation to successfully attain the quasi-intermediate states but also monitored its reprogramming into a cancer cell state. The nanoprobes substantially amplified weak intracellular Raman signals to capture the molecular events during a CSC transformation. The detection of cancer was achieved with 100% accuracy. We experimentally demonstrated that the molecular signatures of CSC reprogramming are cancer-type specific. This observation enabled us to identify the origin of metastasis with 100% accuracy, providing more clarity on the relatively unknown quasi-intermediate states. This first demonstration of CSC-based tracking of metastasis evolution has the potential to provide an insightful perspective of tumorigenesis that could be useful in cancer diagnosis and prognosis as well as in the monitoring of therapeutic interventions.

Metabolic Impact of Anticancer Drugs Pd2Spermine and Cisplatin on the Brain of Healthy Mice

The new palladium agent Pd2Spermine (Spm) has been reported to exhibit promising cytotoxic properties, while potentially circumventing the known disadvantages associated to cisplatin therapeutics, namely acquired resistance and high toxicity. This work presents a nuclear magnetic resonance (NMR) metabolomics study of brain extracts obtained from healthy mice, to assess the metabolic impacts of the new Pd2Spm complex in comparison to that of cisplatin. The proton NMR spectra of both polar and nonpolar brain extracts were analyzed by multivariate and univariate statistics, unveiling several metabolite variations during the time course of exposition to each drug (1–48 h). The distinct time-course dependence of such changes revealed useful information on the drug-induced dynamics of metabolic disturbances and recovery periods, namely regarding amino acids, nucleotides, fatty acids, and membrane precursors and phospholipids. Putative biochemical explanations were proposed, based on existing pharmacokinetics data and previously reported metabolic responses elicited by the same metal complexes in the liver of the same animals. Generally, results suggest a more effective response of brain metabolism towards the possible detrimental effects of Pd2Spm, with more rapid recovery back to metabolites’ control levels and, thus, indicating that the palladium drug may exert a more beneficial role than cDDP in relation to brain toxicity.

Who's Who? Discrimination of Human Breast Cancer Cell Lines by Raman and FTIR Microspectroscopy

(1) Breast cancer is presently the leading cause of death in women worldwide. This study aims at identifying molecular biomarkers of cancer in human breast cancer cells, in order to differentiate highly aggressive triple-negative from non-triple-negative cancers, as well as distinct triple-negative subtypes, which is currently an unmet clinical need paramount for an improved patient care. (2) Raman and FTIR (Fourier transform infrared) microspectroscopy state-of-the-art techniques were applied, as highly sensitive, specific and non-invasive methods for probing heterogeneous biological samples such as human cells. (3) Particular biochemical features of malignancy were unveiled based on the cells' vibrational signature, upon principal component analysis of the data. This enabled discrimination between TNBC (triple-negative breast cancer) and non-TNBC, TNBC MSL (mesenchymal stem cell-like) and TNBC BL1 (basal-like 1) and TNBC BL1 highly metastatic and low-metastatic cell lines. This specific differentiation between distinct TNBC subtypes-mesenchymal from basal-like, and basal-like 1 with high-metastatic potential from basal-like 1 with low-metastatic potential-is a pioneer result, of potential high impact in cancer diagnosis and treatment.

Breast cancer or surrounding normal tissue? A successful discrimination by FTIR or Raman microspectroscopy

Breast cancer is a type of cancer with the highest incidence worldwide in 2021, with early diagnosis and rapid treatment intervention being the reasons for the decreasing mortality rate associated with the disease.

Investigating the cellular responses of osteosarcoma to cisplatin by confocal Raman microspectroscopy

Confocal Raman Microspectroscopy (CRM) was employed to clarify the cellular response of cisplatin in osteosarcoma (OS) cells with different dosages and incubation times. The K7M2 mouse osteosarcoma cells were treated by cisplatin in 0 μM (UT group), 20 μM (20 T group), and 40 μM (40 T group) doses for 24-h (24H group) and 48-h (48H group), respectively. Raman spectroscopy was utilized to analyze the drug induced variations of intracellular biochemical components in osteosarcoma cells. The spectral results shows that the main changes in its biochemical composition come from nucleic acids. By adopting three different kernel functions (linear, polynomial, and Gaussian radial basis function (RBF)), principal component analysis combined with support vector machine models (PCA-SVM) was built to address the spectral variations among all investigated groups. Meanwhile, multivariate curve resolution alternating least squares (MCR-ALS) was further utilized to discuss on the chemical interpretation on the acquired spectral results. Moreover, Raman spectral images, which is reconstructed by K-means cluster analysis (KCA) with point-scanned hyperspectral dataset, was applied to illustrate the drug induced compositional and morphological variations in each subcellular region. The achieved results not only prove the application potential of Raman based analytical technique in non-labeled intracellular studies, but also illustrate the detailed compositional and structural information of cisplatin induced OS cell responses from the perspective of multivariate analysis and imaging of Raman spectroscopy.

A New Look into Cancer-A Review on the Contribution of Vibrational Spectroscopy on Early Diagnosis and Surgery Guidance

Simple Summary

Cancer is a leading cause of death worldwide, with the detection of the disease in its early stages, as well as a correct assessment of the tumour margins, being paramount for a successful recovery. While breast cancer is one of most common types of cancer, head and neck cancer is one of the types of cancer with a lower prognosis and poor aesthetic results. Vibrational spectroscopy detects molecular vibrations, being sensitive to different sample compositions, even when the difference was slight. The use of spectroscopy in biomedicine has been extensively explored, since it allows a broader assessment of the biochemical fingerprint of several diseases. This literature review covers the most recent advances in breast and head and neck cancer early diagnosis and intraoperative margin assessment, through Raman and Fourier transform infrared spectroscopies. The rising field of spectral histopathology was also approached. The authors aimed at expounding in a more concise and simple way the challenges faced by clinicians and how vibrational spectroscopy has evolved to respond to those needs for the two types of cancer with the highest potential for improvement regarding an early diagnosis, surgical margin assessment and histopathology.

Abstract

In 2020, approximately 10 million people died of cancer, rendering this disease the second leading cause of death worldwide. Detecting cancer in its early stages is paramount for patients’ prognosis and survival. Hence, the scientific and medical communities are engaged in improving both therapeutic strategies and diagnostic methodologies, beyond prevention. Optical vibrational spectroscopy has been shown to be an ideal diagnostic method for early cancer diagnosis and surgical margins assessment, as a complement to histopathological analysis. Being highly sensitive, non-invasive and capable of real-time molecular imaging, Raman and Fourier transform infrared (FTIR) spectroscopies give information on the biochemical profile of the tissue under analysis, detecting the metabolic differences between healthy and cancerous portions of the same sample. This constitutes tremendous progress in the field, since the cancer-prompted morphological alterations often occur after the biochemical imbalances in the oncogenic process. Therefore, the early cancer-associated metabolic changes are unnoticed by the histopathologist. Additionally, Raman and FTIR spectroscopies significantly reduce the subjectivity linked to cancer diagnosis. This review focuses on breast and head and neck cancers, their clinical needs and the progress made to date using vibrational spectroscopy as a diagnostic technique prior to surgical intervention and intraoperative margin assessment.

Impact of the Pd2Spm (Spermine) Complex on the Metabolism of Triple-Negative Breast Cancer Tumors of a Xenograft Mouse Model

The interest in palladium(II) compounds as potential new anticancer drugs has increased in recent years, due to their high toxicity and acquired resistance to platinum(II)-derived agents, namely cisplatin. In fact, palladium complexes with biogenic polyamines (e.g., spermine, Pd₂Spm) have been known to display favorable antineoplastic properties against distinct human breast cancer cell lines. This study describes the in vivo response of triple-negative breast cancer (TNBC) tumors to the Pd₂Spm complex or to cisplatin (reference drug), compared to tumors in vehicle-treated mice. Both polar and lipophilic extracts of tumors, excised from a MDA-MB-231 cell-derived xenograft mouse model, were characterized through nuclear magnetic resonance (NMR) metabolomics. Interestingly, the results show that polar and lipophilic metabolomes clearly exhibit distinct responses for each drug, with polar metabolites showing a stronger impact of the Pd(II)-complex compared to cisplatin, whereas neither drug was observed to significantly affect tumor lipophilic metabolism. Compared to cisplatin, exposure to Pd₂Spm triggered a higher number of, and more marked, variations in some amino acids, nucleotides and derivatives, membrane precursors (choline and phosphoethanolamine), dimethylamine, fumarate and guanidine acetate, a signature that may be relatable to the cytotoxicity and/or mechanism of action of the palladium complex. Putative explanatory biochemical hypotheses are advanced on the role of the new Pd₂Spm complex in TNBC metabolism.

Unveiling osteosarcoma responses to DAPT combined with cisplatin by using confocal Raman microscopy

The aim of this study was to clarify the dose- and time-dependent effect of the γ-secretase inhibitor (DAPT) combined with cisplatin on osteosarcoma (OS) cells, evaluated by confocal Raman microspectral imaging (CRMI) technology. The intracellular composition significantly changed after combined drug action compared with the sole cisplatin treatment, proving the synergistic effect of DAPT combined with cisplatin on OS cells. The principal component analysis-linear discriminant analysis revealed the main compositional variations by distinguishing spectral characteristics. K-means cluster and univariate imaging were used to visualize the changes in subcellular morphology and biochemical distribution. The results showed that the increase of the DAPT dose and cisplatin treatment time in the combination treatment induced the division of the nucleus in OS cells, and other organelles also showed significant physiological changes compared with the effect of sole cisplatin treatment. After understanding the cellular response to the combined drug treatment at a molecular level, the achieved results provide an experimental fact for developing suitable individualized tumor treatment protocols.

Response of Osteosarcoma Cell Metabolism to Platinum and Palladium Chelates as Potential New Drugs

This paper reports the first metabolomics study of the impact of new chelates Pt₂Spm and Pd₂Spm (Spm = Spermine) on human osteosarcoma cellular metabolism, compared to the conventional platinum drugs cisplatin and oxaliplatin, in order to investigate the effects of different metal centers and ligands. Nuclear Magnetic Resonance metabolomics was used to identify meaningful metabolite variations in polar cell extracts collected during exposure to each of the four chelates. Cisplatin and oxaliplatin induced similar metabolic fingerprints of changing metabolite levels (affecting many amino acids, organic acids, nucleotides, choline compounds and other compounds), thus suggesting similar mechanisms of action. For these platinum drugs, a consistent uptake of amino acids is noted, along with an increase in nucleotides and derivatives, namely involved in glycosylation pathways. The Spm chelates elicit a markedly distinct metabolic signature, where inverse features are observed particularly for amino acids and nucleotides. Furthermore, Pd₂Spm prompts a weaker response from osteosarcoma cells as compared to its platinum analogue, which is interesting as the palladium chelate exhibits higher cytotoxicity. Putative suggestions are discussed as to the affected cellular pathways and the origins of the distinct responses. This work demonstrates the value of untargeted metabolomics in measuring the response of cancer cells to either conventional or potential new drugs, seeking further understanding (or possible markers) of drug performance at the molecular level.

Metallodrug-protein interaction probed by synchrotron terahertz and neutron scattering spectroscopy

This experimental work applied coherent synchrotron-radiation terahertz spectroscopy and inelastic neutron scattering to address two processes directly associated with the mode of action of metal-based anticancer agents that can severely undermine chemotherapeutic treatment: drug binding to human serum albumin, occurring during intravenous drug transport, and intracellular coordination to thiol-containing biomolecules (such as metallothioneins) associated with acquired drug resistance. Cisplatin and two dinuclear platinum (Pt)- and palladium (Pd)-polyamine agents developed by this research group, which have yielded promising results toward some types of human cancers, were investigated. Complementary synchrotron-radiation-terahertz and inelastic neutron scattering data revealed protein metalation, through S- and N-donor ligands from cysteine, methionine, and histidine residues. A clear impact of the Pt and Pd agents was evidenced, drug binding to albumin and metallothionein having been responsible for significant changes in the overall protein conformation, as well as for an increased flexibility and possible aggregation.

Preparation of p-amino salicylic acid-modified polysuccinimide as water-based nanocarriers for enhancing pesticide stability and insecticidal activity

Avermectin (AVM) is a biopesticide with low toxicity and high activity, but has limited use due to its poor water solubility and easy decomposition. A delivery system that can stabilize this biopesticide can play a significant role for improving its biological activity. Herein, water-dispersible functionalized polysuccinimide nanoparticles (PAD) were prepared by a ring-opening reaction and subsequently used to encapsulate AVM via self-assembly to form AVM@PAD nanoparticles with a loading ratio of 10.04 %. The half-life under UV radiation (300 W) of AVM@PAD was three times higher than that of free AVM, demonstrating the excellent protective ability of PAD. In addition, AVM@PAD nanoparticles could sustain the release of AVM for 70 h with a cumulative release rate of 70 %. AVM@PAD nanoparticles also showed a pH-responsive release, and their maximum cumulative release rate was at neutral pH. Moreover, the median lethal concentration (LC₅₀) value of AVM@PAD with respect to Plutella xylostella was 34.50 mg/L, while that of free AVM was 56.05 mg/L. These results showed that the AVM@PAD nanoparticles can potentially and effectively promote drug stability and biological activity in agriculture.

Confocal Raman microspectral analysis and imaging of the drug response of osteosarcoma to cisplatin

Confocal Raman microspectral analysis and imaging were used to elucidate the drug response of osteosarcoma (OS) to cisplatin. Raman spectral data were obtained from OS cells that were untreated (UT group) and treated with 20 µM (20T group) and 40 µM (40T group) cisplatin for 24 hours. Statistical analysis of the changes in specific Raman signals was performed using a one-way ANOVA and multiple Tukey's honest significant difference (HSD) post hoc tests. Principal component analysis-linear discriminant analysis (PCA-LDA) was used to highlight the featured cellular drug responses based on the obtained spectral information. For spectral imaging analysis, k-means cluster analysis (KCA) was adopted to clarify the effect of cisplatin dose changes on the subcellular structure and its biochemical composition. The results suggest that the major biochemical changes induced by cisplatin in OS cells undergoing apoptosis are reduced protein and nucleic acid content. Through univariate analysis, the changes in the distribution of nucleic acids in OS cells induced by different doses of cisplatin were obtained. The combination of Raman spectroscopy and multivariate analysis shows that cisplatin mainly acts on the nucleus and causes changes in the secondary structure of proteins. These results indicate that Raman imaging technology has the potential to offer the basis of dose optimization for personalized cancer treatment by helping to understand in vitro cellular drug interactions.

Preclinical Pharmacokinetics and Biodistribution of Anticancer Dinuclear Palladium(II)-Spermine Complex (Pd2Spm) in Mice

Palladium-based compounds are regarded as potential analogs to platinum anticancer drugs with improved properties. The present study assessed the pharmacokinetics and biodistribution of a dinuclear palladium(II)-spermine chelate (Pd₂Spm), which has previously been shown to possess promising in vitro activity against several therapy-resistant cancers. Using inductively coupled plasma-mass spectrometry, the kinetic profiles of palladium/platinum in serum, serum ultrafiltrate and tissues (kidney, liver, brain, heart, lungs, ovaries, adipose tissue and mammary glands) were studied in healthy female Balb/c mice after a single intraperitoneal bolus injection of Pd₂Spm (3 mg/kg bw) or cisplatin (3.5 mg/kg bw) between 0.5 and 48 h post-injection. Palladium in serum exhibited biphasic kinetics with a terminal half-life of 20.7 h, while the free palladium in serum ultrafiltrate showed a higher terminal half-life than platinum (35.5 versus 31.5 h). Palladium was distributed throughout most of the tissues except for the brain, with the highest values in the kidney, followed by the liver, lungs, ovaries, adipose tissue and mammary glands. The in vitro cellular accumulation was also evaluated in breast cancer cells, evidencing a passive diffusion as a mechanism of Pd₂Spm’s cellular entry. This study reports, for the first time, the favorable pharmacokinetics and biodistribution of Pd₂Spm, which may become a promising pharmacological agent for cancer treatment.

Novel Insights into Mice Multi-Organ Metabolism upon Exposure to a Potential Anticancer Pd(II)-Agent

Pd(II)-compounds are presently regarded as promising anticancer drugs, as an alternative to Pt(II)-based drugs (e.g., cisplatin), which typically trigger severe side-effects and acquired resistance. Dinuclear Pd(II) complexes with biogenic polyamines such as spermine (Pd₂Spm) have exhibited particularly beneficial cytotoxic properties, hence unveiling the importance of understanding their impact on organism metabolism. The present study reports the first nuclear magnetic resonance (NMR)-based metabolomics study to assess the in vivo impact of Pd₂Spm on the metabolism of healthy mice, to identify metabolic markers with possible relation to biotoxicity/side-effects and their dynamics. The changes in the metabolic profiles of both aqueous and lipophilic extracts of mice kidney, liver, and breast tissues were evaluated, as a function of drug-exposure time, using cisplatin as a reference drug. A putative interpretation was advanced for the metabolic deviations specifically triggered by Pd₂Spm, this compound generally inducing faster metabolic response and recovery to control levels for all organs tested, compared to cisplatin (except for kidney lipid metabolism). These results constitute encouraging preliminary metabolic data suggestive of potential lower negative effects of Pd₂Spm administration.

Analysis of Fixed and Live Single Cells Using Optical Photothermal Infrared with Concomitant Raman Spectroscopy

This paper reports the first use of a novel completely optically based photothermal method (O-PTIR) for obtaining infrared spectra of both fixed and living cells using a quantum cascade laser (QCL) and optical parametric oscillator (OPO) laser as excitation sources, thus enabling all biologically relevant vibrations to be analyzed at submicron spatial resolution. In addition, infrared data acquisition is combined with concomitant Raman spectra from exactly the same excitation location, meaning the full vibrational profile of the cell can be obtained. The pancreatic cancer cell line MIA PaCa-2 and the breast cancer cell line MDA-MB-231 are used as model cells to demonstrate the capabilities of the new instrumentation. These combined modalities can be used to analyze subcellular structures in both fixed and, more importantly, live cells under aqueous conditions. We show that the protein secondary structure and lipid-rich bodies can be identified on the submicron scale.

Unveiling dose- and time-dependent osteosarcoma cell responses to the γ-secretase inhibitor, DAPT, by confocal Raman microscopy

Using confocal Raman micro-spectroscopy, this study aims to elucidate the cellular responses of the γ-secretase inhibitor, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT), in osteosarcoma (OS) cells in a dose- and time-dependent manner. The K7M2 murine OS cell line was treated with different DAPT doses (0, 10, 20, and 40 μM) for 24 and 48 hours before investigations. Significant compositional changes (nucleic acids, protein and lipid) after DAPT treatment were addressed, which testified inhibitory effect of DAPT on the growth of OS cells. Moreover, both partial least squares-discriminant analysis (PLS-DA) and principal component analysis-linear discriminant analysis (PCA-LDA) analyses revealed governing composition variations among groups by distinguishing their spectral characteristics. Furthermore, by adopting leave-one-out cross validation method, it is shown that PLS-DA exhibited more classification capacity than PCA-LDA algorithm. Hence, by understanding the DAPT-based cellular variations, the achieved results provided an experimental foundation to establish new DAPT-based anticancer therapeutic strategies, and preclinical Raman analytical methodologies on drug-cell interactions.

Metabolic Aspects of Palladium(II) Potential Anti-Cancer Drugs

This mini-review reports on the existing knowledge of the metabolic effects of palladium [Pd(II)] complexes with potential anticancer activity, on cell lines and murine models. Most studies have addressed mononuclear Pd(II) complexes, although increasing interest has been noted in bidentate complexes, as polynuclear structures. In addition, the majority of records have reported in vitro studies on cancer cell lines, some including the impact on healthy cells, as potentially informative in relation to side effects. Generally, these studies address metabolic effects related to the mechanisms of induced cell death and antioxidant defense, often involving the measurement of gene and protein expression patterns, and evaluation of the levels of reactive oxygen species or specific metabolites, such as ATP and glutathione, in relation to mitochondrial respiration and antioxidant mechanisms. An important tendency is noted toward the use of more untargeted approaches, such as the use of omic sciences e.g., proteomics and metabolomics. In the discussion section of this mini-review, the developments carried out so far are summarized and suggestions of possible future developments are advanced, aiming at recognizing that metabolites and metabolic pathways make up an important part of cell response and adaptation to therapeutic agents, their further study potentially contributing valuably for a more complete understanding of processes such as biotoxicity or development of drug resistance.

Confocal Raman microspectroscopic analysis on the time-dependent impact of DAPT, a γ-secretase inhibitor, to osteosarcoma cells

Confocal Raman microspectroscopy (CRM) analysis provides subcellular compositional and morphology related information. In this study, we used CRM in conjunction with multivariate statistical analysis to elucidate the time-dependent impact of the γ-secretase inhibitor, DAPT (N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester) of osteosarcoma (OS) cells. The interactions of DAPT (20 μM) with a murine OS cell line K7M2 at 24 and 48 h were monitored. The spectral characteristics of drug action were identified to illustrate the cellular compositional alterations, showing that DAPT induced apoptosis by reducing the protein, lipid and nucleic acid content and structural changes. Multivariate algorithms, principal component analysis (PCA) and linear discriminant analysis (LDA) revealed a clear separation among cells in the untreated control (UT), 24H (DAPT-treated for 24 h), and 48H (DAPT-treated for 48 h) groups, achieving sensitivities of 100%, 96%, 100% and specificities of 98%, 100%, 100%, respectively. After point-scanned spectral imaging, K-means clustering analysis (KCA) was further used to visualize sub-cellular morphological changes and the underlying spectral characteristics in a temporal sequence. Compared with the UT group, Raman imaging results exhibited gradually increased nuclear division of OS cells with DAPT treatment duration extension, along with changes in the physiology of other organelles within the cell. By providing a unique perspective for understanding the temporary cellular responses to DAPT at molecular level, the achieved results form the foundation of strategies for the application of CRM and other Raman-based techniques for studying the therapeutic responses of other anticancer agents in cancer model systems.

Role of intracellular water in the normal-to-cancer transition in human cells-insights from quasi-elastic neutron scattering

The transition from normal to malignant state in human cells is still a poorly understood process. Changes in the dynamical activity of intracellular water between healthy and cancerous human cells were probed as an innovative approach for unveiling particular features of malignancy and identifying specific reporters of cancer. Androgen-unresponsive prostate and triple-negative breast carcinomas were studied as well as osteosarcoma, using the technique of quasi-elastic neutron scattering. The cancerous cells showed a considerably higher plasticity relative to their healthy counterparts, this being more significant for the mammary adenocarcinoma. Also, the data evidence that the prostate cancer cells display the highest plasticity when compared to triple-negative mammary cancer and osteosarcoma, the latter being remarkably less flexible. Furthermore, the results suggest differences between the flexibility of different types of intracellular water molecules in normal and cancerous cells, as well as the number of molecules involved in the different modes of motion. The dynamics of hydration water molecules remain virtually unaffected when going from healthy to cancer cells, while cytoplasmic water (particularly the rotational motions) undergoes significant changes upon normal-to-cancer transition. The results obtained along this study can potentially help to understand the variations in cellular dynamics underlying carcinogenesis and tumor metastasis, with an emphasis on intracellular water.

Monitoring the Progress and Healing Status of Burn Wounds Using Infrared Spectroscopy

Burns are one of the leading causes of morbidity worldwide and the most costly traumatic injuries. A better understanding of the molecular mechanisms in wound healing is required to accelerate tissue recovery and reduce the health economic impact. However, the standard techniques used to evaluate the biological events associated to wound repair are laborious, time-consuming, and/or require multiple assays/staining. Therefore, this study aims to evaluate the feasibility of Fourier transform infrared (FT-IR) spectroscopy to monitor the progress and healing status of burn wounds. Burn injuries were induced on Wistar rats by water vapor exposure and biopsied for further histopathological and spectroscopic evaluation at four time-points (3, 7, 14, and 21 days). Spectral data were preprocessed and compared by principal component analysis. Pairwise comparison of post-burn groups to each other revealed that metabolic activity induced by thermal injury decreases as the healing progresses. Higher amounts of carbohydrates, proteins, lipids, and nucleic acids were evidenced on days 3 and 7 compared to healthy skin and reduced amounts of these molecular structural units on days 14 and 21 post-burn. FT-IR spectroscopy was used to determine the healing status of a wound based on the biochemical information retained by spectral signatures in each phase of healing. Our findings demonstrate that FT-IR spectroscopy can monitor the biological events triggered by burn trauma as well as to detect the wound status including full recovery based on the spectral changes associated to the biochemical events in each phase.

Supercritical CO2 Processing Generates Aqueous Cisplatin Solutions with Enhanced Cancer Specificity

Cisplatin is a highly toxic material used clinically as a potent chemotherapeutic. While effective against some cancers, toxicity limits widespread use and low solubility confounds delivery. To formulate a better tolerated and more water-soluble form of cisplatin, we designed a rapid expansion of supercritical solutions (RESS) technique with supercritical carbon dioxide (sc-CO₂) to collect nanoclusters of cisplatin embedded in dry ice, in a dual-stage collection vessel cooled to liquid nitrogen temperature. These nanoclusters were solubilized in deionized water and further concentrated (up to 51.3 mM) by a Rotovap process, yielding stable cisplatin solutions with solubility up to 15 × (w/w) greater than that of normal cisplatin. Extensive material characterizations of the solutions were carried out to determine any chemical and/or structural changes of the RESS-processed cisplatin. In vitro cytotoxicity studies of these aqueous solutions showed increased cell viability and early apoptosis compared to equivalent concentrations of standard cisplatin solutions. In vivo studies using zebrafish embryos revealed that standard cisplatin solutions were acutely toxic and caused death of rapidly proliferating cells compared to RESS-processed cisplatin, which were better tolerated with reduced general cell death. Increased water solubility and matched chemical identity of RESS-processed aqueous cisplatin solutions indicate the potential to open up novel drug-delivery routes, which is beneficial for new pharmaceutical design and development.

Confocal Raman Spectral Imaging Study of DAPT, a γ-secretase Inhibitor, Induced Physiological and Biochemical Reponses in Osteosarcoma Cells

Confocal Raman microspectral imaging was adopted to elucidate the cellular drug responses of osteosarcoma cells (OC) to N-[N-(3, 5-difluorophenyl acetyl)-L-alanyl]-sphenylglycine butyl ester (DAPT), a γ-secretase inhibitor, by identifying the drug induced subcellular compositional and structural changes. Methods: Spectral information were acquired from cultured osteosarcoma cells treated with 0 (Untreated Group, UT), 10 (10 μM DAPT treated, 10T), 20 μM (20 μM DAPT treated, 20T) DAPT for 24 hours. A one-way ANOVA and Tukey's honest significant difference (HSD) post hoc multiple test were sequentially applied to address spectral features among three groups. Multivariate algorithms such as K-means clustering analysis (KCA) and Principal component analysis (PCA) were used to highlight the structural and compositional differences, while, univariate imaging was applied to illustrate the distribution pattern of certain cellular components after drug treatment. Results: Major biochemical changes in DAPT-induced apoptosis came from changes in the content and structure of proteins, lipids, and nucleic acids. By adopted multivariate algorithms, the drug induced cellular changes was identified by the morphology and spectral characteristics between untreated cells and treated cells, testified that DAPT mainly acted in the nuclear region. With the increase of the drug concentration, the content of main subcellular compositions, such nucleic acid, protein, and lipid decreased. In an addition, DAPT-induced nuclear fragmentation and apoptosis was depicted by the univariate Raman image of major cellular components (nucleic acids, proteins and lipids). Conclusions: The achieved Raman spectral and imaging results illustrated detailed DAPT-induced subcellular compositional and structural variations as a function of drug dose. Such observations can not only explain drug therapeutic mechanisms of OC DAPT treatment, and also provide new insights for accessing the medicine curative efficacy and predicting prognosis.

A New Look into the Mode of Action of Metal-Based Anticancer Drugs

The mode of action of Pt- and Pd-based anticancer agents (cisplatin and Pd₂Spm) was studied by characterising their impact on DNA. Changes in conformation and mobility at the molecular level in hydrated DNA were analysed by quasi-elastic and inelastic neutron scattering techniques (QENS and INS), coupled to Fourier transform infrared (FTIR) and microRaman spectroscopies. Although INS, FTIR and Raman revealed drug-triggered changes in the phosphate groups and the double helix base pairing, QENS allowed access to the nanosecond motions of the biomolecule’s backbone and confined hydration water within the minor groove. Distinct effects were observed for cisplatin and Pd₂Spm, the former having a predominant effect on DNA’s spine of hydration, whereas the latter had a higher influence on the backbone dynamics. This is an innovative way of tackling a drug’s mode of action, mediated by the hydration waters within its pharmacological target (DNA).

DNA-Related Modifications in a Mixture of Human Lympho-Monocyte Exposed to Radiofrequency Fields and Detected by Raman Microspectroscopy Analysis

Human exposure to electromagnetic fields (EMFs) has risen considerably during the last decades, because of the industrial and technical development and the consequent increase of artificial EMFs sources. In particular, blood is largely involved in the environmental EMF exposure, because it is located everywhere in the human body. Lympho-monocyte cells are blood components that protect the human organism against infections. In this study, we investigate biochemical changes in lympho-monocyte cells extracted from human peripheral blood after exposure to EMFs at 1.8 GHz frequency and 200 V/m electric field strength for times ranging from 5 to 20 h inside a reverberation chamber. Some mixtures of cells, coming from many human subjects, were exposed and successively investigated by means of Raman micro-spectroscopy technique and principal components analysis. The spectral analysis was able to detect variations of the biochemical composition of the nucleus of exposed cells. Such modifications are mainly detectable as an intensity decrease of some DNA and nucleic acid Raman peaks with respect to the intensity of some protein peaks and they were most evident in the case of 20 h exposed samples. These results were in agreement with the increase of reactive oxygen species (ROS) production, observed in the exposed cells. Overall, the obtained results point out that EMFs exposure may induce modifications of the DNA in some blood cells of long-term exposed people.

Vibrational Spectroscopy Fingerprinting in Medicine: from Molecular to Clinical Practice

In the last two decades, Fourier Transform Infrared (FTIR) and Raman spectroscopies turn out to be valuable tools, capable of providing fingerprint-type information on the composition and structural conformation of specific molecular species. Vibrational spectroscopy’s multiple features, namely highly sensitive to changes at the molecular level, noninvasive, nondestructive, reagent-free, and waste-free analysis, illustrate the potential in biomedical field. In light of this, the current work features recent data and major trends in spectroscopic analyses going from in vivo measurements up to ex vivo extracted and processed materials. The ability to offer insights into the structural variations underpinning pathogenesis of diseases could provide a platform for disease diagnosis and therapy effectiveness evaluation as a future standard clinical tool.

Chemotherapeutic Targets in Osteosarcoma: Insights from Synchrotron-MicroFTIR and Quasi-Elastic Neutron Scattering

This study aimed at the development of improved drugs against human osteosarcoma, which is the most common primary bone tumor in children and teenagers with a low prognosis. New insights into the impact of an unconventional Pd(II) anticancer agent on human osteosarcoma cells were obtained by synchrotron radiation-Fourier transform infrared microspectroscopy and quasi-elastic neutron scattering (QENS) experiments from its effect on the cellular metabolism to its influence on intracellular water, which can be regarded as a potential secondary pharmacological target. Specific infrared biomarkers of drug action were identified, enabling a molecular-level description of variations in cellular biochemistry upon drug exposure. The main changes were detected in the protein and lipid cellular components, namely, in the ratio of unsaturated-to-saturated fatty acids. QENS revealed reduced water mobility within the cytoplasm for drug-treated cells, coupled to a disruption of the hydration layers of biomolecules. Additionally, the chemical and dynamical profiles of osteosarcoma cells were compared to those of metastatic breast cancer cells, revealing distinct dissimilarities that may influence drug activity.

Remarkably Intricate Raman Spectra of Platinum(II)-Ligand Skeletal Modes in Diamminedihalido Complexes

More than 100 calculations of vibrational frequencies for cis-[Pt(NH₃)₂X₂] (X = Cl^-, Br^-) and trans-[Pt(NH₃)₂Cl₂] have been published over the past 25 years. The high-quality Raman spectra presented here have sufficient resolution in the crucial region of metal-ligand modes to permit an assessment of frequency calculations. The peaks for symmetric and antisymmetric Pt-Cl stretching modes ν_s and ν_a are resolved in the 312-333 cm^-1 region. Frequency variations due to ³⁵Cl and ³⁷Cl isotopes are shown to be comparable in size to the differences between ν_s and ν_a. Peaks corresponding to the two Pt-Br stretching frequencies are observed at 213 and 218 cm^-1 and Pt-N stretching frequencies for all compounds between 485 and 540 cm^-1. The crystal structures of trans-[Pt(NH₃)₂Cl₂] and cis-[Pt(NH₃)₂Br₂] at 300 and 120 K are reported and complement the variable-temperature vibrational frequencies.

Live single cell analysis using synchrotron FTIR microspectroscopy: development of a simple dynamic flow system for prolonged sample viability

Synchrotron radiation Fourier transform infrared microspectroscopy (SR-microFTIR) of live biological cells has the potential to provide far greater biochemical and morphological detail than equivalent studies using dehydrated, chemically-fixed single cells. Attempts to measure live cells using microFTIR are complicated by the aqueous environment required and corresponding strong infrared absorbance by water. There is also the additional problem of the limited lifetime of the cells outside of their preferred culture environment. In this work, we outline simple, cost-effective modifications to a commercially available liquid sample holder to perform single live cell analysis under an IR microscope and demonstrate cell viability up to at least 24 hours. A study using this system in which live cells have been measured at increasing temperature has shown spectral changes in protein bands attributed to α-β transition, consistent with other published work, and proves the ability to simultaneously induce and measure biochemical changes. An additional study of deuterated palmitic acid (D31-PA) uptake at different timepoints has made use of over 200 individual IR spectra collected over ∼4 hours, taking advantage of the ability to maintain viable cell samples for longer periods of time in the measurement environment, and therefore acquire greatly increased numbers of spectra without compromising on spectral quality. Further developments of this system are planned to widen the range of possible experiments, and incorporate more complex studies, including drug-cell interaction.

Anticancer activity of palladium-based complexes against triple-negative breast cancer

Treatment of triple-negative breast carcinoma (TNBC) remains an unmet medical need with no targeted therapy available to date. Accounting for 10-30% of all human breast cancer tumors, this mammary carcinoma subtype has a particularly poor prognosis owing to its high metastatic potential, aggressive biology and limited pharmacological treatment options. Platinum chemotherapeutics are the mainstay therapy in patients with TNBC but their clinical use is limited by severe toxicity and acquired resistance. Palladium-based complexes are appealing alternative metal-based drugs because of significant similarities regarding structure and coordination chemistry with the platinum agents. This review summarizes the knowledge gathered so far on 121 Pd(II) complexes, emphasizing their anticancer activity and putative pharmacological targets toward TNBC.

Cisplatin-Membrane Interactions and Their Influence on Platinum Complexes Activity and Toxicity

Cisplatin and other platinum(II) analogs are widely used in clinical practice as anti-cancer drugs for a wide range of tumors. The primary mechanism by which they exert their action is through the formation of adducts with genomic DNA. However, multiple cellular targets by platinum(II) complexes have been described. In particular, the early events occurring at the plasma membrane (PM), i.e., platinum-membrane interactions seem to be involved in the uptake, cytotoxicity and cell-resistance to cisplatin. In fact, PM influences signaling events, and cisplatin-induced changes on membrane organization and fluidity were shown to activate apoptotic pathways. This review critically discusses the sequence of events caused by lipid membrane-platinum interactions, with emphasis on the mechanisms that lead to changes in the biophysical properties of the membranes (e.g., fluidity and permeability), and how these correlate with sensitivity and resistance phenotypes of cells to platinum(II) complexes.

Anticancer drug impact on DNA – a study by neutron spectroscopy coupled with synchrotron-based FTIR and EXAFS

Complementary information on drug–DNA interplay has been achieved for Pt/Pd anticancer agents, by a combined QENS, SR-FTIR-ATR and EXAFS approach.

Non plasmonic semiconductor quantum SERS probe as a pathway for in vitro cancer detection

Surface-enhanced Raman scattering (SERS)-based cancer diagnostics is an important analytical tool in early detection of cancer. Current work in SERS focuses on plasmonic nanomaterials that suffer from coagulation, selectivity, and adverse biocompatibility when used in vitro, limiting this research to stand-alone biomolecule sensing. Here we introduce a label-free, biocompatible, ZnO-based, 3D semiconductor quantum probe as a pathway for in vitro diagnosis of cancer. By reducing size of the probes to quantum scale, we observed a unique phenomenon of exponential increase in the SERS enhancement up to ~106 at nanomolar concentration. The quantum probes are decorated on a nano-dendrite platform functionalized for cell adhesion, proliferation, and label-free application. The quantum probes demonstrate discrimination of cancerous and non-cancerous cells along with biomolecular sensing of DNA, RNA, proteins and lipids in vitro. The limit of detection is up to a single-cell-level detection.