Polyoxometalate-Based Nanomaterials Toward Efficient Cancer Diagnosis and Therapy

Prussian blue nanoparticle-based pH-responsive self-assembly for enhanced photothermal and chemotherapy of tumors

In recent years, there has been growing interest in size-transformable nanoplatforms that exhibit active responses to acidic microenvironments, presenting promising prospects in the field of nanomedicine for tumor therapy. However, the design and fabrication of such size-adjustable nanotherapeutics pose significant challenges compared to size-fixed nanocomposites, primarily due to their distinct pH-responsive requirements. In this study, we developed pH-activated-aggregating nanosystems to integrate chemotherapy and photothermal therapy by creating size-transformable nanoparticles based on Prussian blue nanoparticles (PB NPs) anchored with acid-responsive polyoxometalates (POMs) quantum dots via electrostatic interactions (PPP NPs). Subsequently, we utilized doxorubicin (DOX) as a representative drug to formulate PPPD NPs. Notably, PPPD NPs exhibited a significant response to acidic conditions, resulting in changes in surface charge and rapid aggregation of PPP NPs. Furthermore, the aggregated PPP NPs demonstrated excellent photothermal properties under near-infrared laser irradiation. Importantly, PPPD NPs prolonged their retention time in tumor cells via a size-transformation approach. In vitro cellular assays revealed that the anticancer efficacy of PPPD NPs was significantly enhanced. The IC50 values for the PPPD NPs groupand the PPPD NPs + NIR group were 50.11 μg/mL and 30.9 μg/mL. Overall, this study introduces a novel strategy for cancer therapy by developing size-aggregating nano-drugs with stimuli-responsive properties, holding promise for improved therapeutic outcomes in future combination approaches involving photothermal therapy and chemotherapy.

Assessing the Influence of Confinement on the Stability of Polyoxometalate-Functionalized Surfaces: A Soft Sequential Immobilization Approach for Electrochromic Devices

A functionalization process has been developed and the experimental conditions optimized allowing the immobilization of first-row transition metal (Mn+) containing polyoxometalates (POMs) with the formula [M(H2O)P2W17O61](10-n)- on transparent indium-tin oxide (ITO) electrodes for electrochromic applications. Both flat ITO grafted with 4-sulfophenyl moieties and sulfonate-functionalized vertically oriented silica films on ITO have been used as electrode supports to evaluate possible confinement effects provided by the mesoporous matrix on the stability of the modified surfaces and their electrochromic properties. Functionalization involved a two-step sequential process: (i) the immobilization of hexaaqua metallic ions, such as Fe(H2O)63+, onto the sulfonate-functionalized materials achieved through hydrogen bonding interactions between the sulfonate functions and aqua ligands (water molecules) coordinated to the metallic ions facilitating and stabilizing the attachment of the metallic ions to the sulfonated surfaces; (ii) their coordination to [P2W17O61]10- species to generate "in situ" the target [Fe(H2O)P2W17O61]7- moieties. Comparison of the characterized surfaces clearly evidenced a significant improvement in the long-term stability of the nanostructured [Fe(H2O)P2W17O61]7--functionalized silica films compared to the less constrained flat [Fe(H2O)P2W17O61]7--modified ITO electrodes for which a rapid loss of [P2W17O61]10- species was observed. Concordantly, the [Fe(H2O)P2W17O61]7- POM confined in the mesoporous films coated on ITO gave rise to much better and stable electrochromic properties, with a transmittance modulation of 40% at 515 nm.

Selective Hydrolysis of Ovalbumin by Zr-Based Lacunary Polyoxotungstate in Surfactant Solutions

This study aims to design an artificial metalloprotease based on a Zr-containing polyoxometalate Na8[Zr(W5O18)2] [Zr(W5)2] for the hydrolysis of ovalbumin (OVA) in the presence of different surfactants, which can be used in many areas of the biological and medical sciences, particularly for targeted proteolytic drug design. For this reason, parameters, including the free energy of binding, the chemical nature of amino acid residues, secondary structures, and electrostatic potentials, of Zr(W5)2-OVA and Zr(W5)2-OVA-surfactant were analyzed by molecular docking simulations. The investigations showed that the presence of surfactants decreases the binding affinity of Zr(W5)2 for OVA amino acids, and hydrogen bonds and van der Waals interactions are formed between Zr(W5)2 and OVA amino acids. Additionally, GROMACS further illustrated the significance of SDS and CTAB surfactants in influencing the conformational changes of the OVA that lead to selective protein hydrolysis. In agreement with molecular dynamics simulation results, the experimental analysis showed more protein hydrolysis for the Zr(W5)2-OVA-surfactant systems. For instance, circular dichroism spectroscopy indicated that Zr(W5)2-OVA-CTAB and Zr(W5)2-OVA-TX-100 were more hydrolytically efficient due to the increased level of β-structures rather than α-chains, which showed that surfactants can facilitate the accessibility of Zr(W5)2 to the cleavage sites by inducing partial unfolding of the OVA structure.

Insight into small-molecule inhibitors targeting extracellular nucleotide pyrophosphatase/phosphodiesterase1 for potential multiple human diseases

Extracellular nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) has been identified as a type II transmembrane glycoprotein. It plays a crucial role in various biological processes, such as bone mineralization, cancer cell proliferation, and immune regulation. Consequently, ENPP1 has garnered attention as a promising target for pharmacological interventions. Despite its potential, the development of clinical-stage ENPP1 inhibitors for solid tumors, diabetes, and silent rickets remains limited. However, there are encouraging findings from preclinical trials involving small molecules exhibiting favorable therapeutic effects and safety profiles. This perspective aims to shed light on the structural properties, biological functions and the relationship between ENPP1 and diseases. Additionally, it focuses on the structure-activity relationship of ENPP1 inhibitors, with the intention of guiding the future development of new and effective ENPP1 inhibitors.

Self-Assembled Materials Based on Fully Aromatic Peptides: The Impact of Tryptophan, Tyrosine, and Dopa Residues

Peptides are able to self-organize in structural elements including cross-β structures. Taking advantage of this tendency, in the last decades, peptides have been scrutinized as molecular elements for the development of multivalent supramolecular architectures. In this context, different classes of peptides, also with completely aromatic sequences, were proposed. Our previous studies highlighted that the (FY)3 peptide, which alternates hydrophobic phenylalanine and more hydrophilic tyrosine residues, is able to self-assemble, thanks to the formation of both polar and apolar interfaces. It was observed that the replacement of Phe and Tyr residues with other noncoded aromatic amino acids like 2-naphthylalanine (Nal) and Dopa affects the interactions among peptides with consequences on the supramolecular organization. Herein, we have investigated the self-assembling behavior of two novel (FY)3 analogues with Trp and Dopa residues in place of the Phe and Tyr ones, respectively. Additionally, PEGylation of the N-terminus was analyzed too. The supramolecular organization, morphology, and capability to gel were evaluated using complementary techniques, including fluorescence, Fourier transform infrared spectroscopy, and scanning electron microscopy. Structural periodicities along and perpendicular to the fiber axis were detected by grazing incidence wide-angle X-ray scattering. Finally, molecular dynamics studies provided interesting insights into the atomic structure of the cross-β that constitutes the basic motif of the assemblies formed by these novel peptide systems.

Patterned immobilization of polyoxometalate-loaded mesoporous silica particles via amine-ene Michael additions on alkene functionalized surfaces

Polyoxometalates (POM) are anionic oxoclusters of early transition metals that are of great interest for a variety of applications, including the development of sensors and catalysts. A crucial step in the use of POM in functional materials is the production of composites that can be further processed into complex materials, e.g. by printing on different substrates. In this work, we present an immobilization approach for POMs that involves two key processes: first, the stable encapsulation of POMs in the pores of mesoporous silica nanoparticles (MSPs) and, second, the formation of microstructured arrays with these POM-loaded nanoparticles. Specifically, we have developed a strategy that leads to water-stable, POM-loaded mesoporous silica that can be covalently linked to alkene-bearing surfaces by amine-Michael addition and patterned into microarrays by scanning probe lithography (SPL). The immobilization strategy presented facilitates the printing of hybrid POM-loaded nanomaterials onto different surfaces and provides a versatile method for the fabrication of POM-based composites. Importantly, POM-loaded MSPs are useful in applications such as microfluidic systems and sensors that require frequent washing. Overall, this method is a promising way to produce surface-printed POM arrays that can be used for a wide range of applications.

Polyoxometalate-Guanosine Monophosphate Hydrogels with Haloperoxidase-like Activity for Antibacterial Performance

Haloperoxidases represent an important class of enzymes that nature adopts as a defense mechanism to combat the colonial buildup of microorganisms on surfaces, commonly known as biofouling. Subsequently, there has been tremendous focus on the development of artificial haloperoxidase mimics that can catalyze the oxidation of X- (halide ion) in the presence of H2O2 to form HOX. The natural intermediate HOX disrupts the bacterial quorum sensing, thus preventing biofilm formation. Herein, we report a simple method for the formation of supramolecular hydrogels through the self-assembly of Keggin-structured polyoxometalates, phosphotungstic acid, and silicotungstic acid with the small biomolecule guanosine monophosphate (GMP) in an aqueous medium. The polyoxometalate-GMP hydrogels that contained highly entangled nanofibers were mechanically robust and showed thixotropic properties. The gelation of the polyoxometalates with GMP not only rendered manifold enhancement in biocompatibility but also the fibril network in the hydrogel provided high water wettability and the polyoxometalates acted as an efficient haloperoxidase mimic to trigger oxidative iodination, as demonstrated by a haloperoxidase assay. The antifouling activity of the phosphotungstic acid-GMP hydrogel was demonstrated against both Gram-positive and Gram-negative bacteria, which showed enhanced antibacterial performance of the hydrogel as compared to the polyoxometalate alone. We envision that the polyoxometalate-GMP hydrogels may facilitate mechanically robust coatings in a simple pathway that can be useful for antifouling applications.

A polyoxomolybdate-based hybrid nano capsule as an antineoplastic agent

Polyoxometalates (POMs) are versatile anionic clusters which have attracted a lot of attention in biomedical investigations. To counteract the increasing resistance effect of cancer cells and the high toxicity of chemotherapeutic treatments, POM-based metallodrugs can be strategically synthesized by adjusting the stereochemical and physicochemical features of POMs. In the present report a polyoxomolybdate (POMo) based organic-inorganic hybrid solid (C6H16N)(C6H15N)2[Mo8O26]·3H2O, solid 1, has been synthesized and its antitumoral activities have been investigated against three cancer cell lines namely, A549 (Lung cancer), HepG2 (Liver cancer), and MCF-7 (Breast cancer) with IC50 values 56.2 μmol L-1, 57.3 μmol L-1, and 55.2 μmol L-1 respectively. The structural characterization revealed that solid 1 consists of an octa molybdate-type cluster connected by three triethylamine molecules via hydrogen bonding interactions. The electron microscopy analysis suggests the nanocapsule-like morphology of solid 1 in the size range of 50-70 nm. The UV-vis absorption spectra were used to assess the binding ability of synthesized POM-based solid 1 to calf thymus DNA (ctDNA), which further explained the binding interaction between POMo and ctDNA and the binding constant was calculated to be 2.246 × 103 giving evidence of groove binding.

Chitosan-Imidazolium Core-Shell Nanoparticles of Gd-Mn-Mo Polyoxometalate as Novel Potential MRI Nano-Agent for Breast Cancer Detection

Polyoxometalates (POMs) are mineral nanoclusters with many advantages in various diagnostic fields, in particular cancer detection. This study aimed to synthesize and evaluate the performance of gadolinium-manganese-molybdenum polyoxometalate (Gd-Mn-Mo; POM) nanoparticles coated with chitosan-imidazolium (POM@CSIm NPs) for detecting 4T1 breast cancer cells by magnetic resonance imaging in vitro and in vivo. The POM@Cs-Im NPs were fabricated and characterized by FTIR, ICP-OES, CHNS, UV-visible, XRD, VSM, DLS, Zeta potential, and SEM. Cytotoxicity, cellular uptake, and MR imaging in vivo and in vitro of L929 and 4T1 cells were also assessed. The efficacy of nanoclusters was demonstrated using MR images of BALB/C mice bearing a 4T1 tumor in vivo. The evaluation of the in vitro cytotoxicity of the designed NPs showed their high biocompatibility. In fluorescence imaging and flow cytometry, NPs had a higher uptake rate by 4T1 than L929 (p < 0.05). Furthermore, NPs significantly increased the signal strength of MR images, and its relaxivity (r1) was calculated as 4.71 mM^-1 s^-1. MR imaging also confirmed the attachment of nanoclusters to cancer cells and their selective accumulation in the tumor region. Overall, the results showed that fabricated POM@CSIm NPs have considerable potential as an MR imaging nano-agent for early 4T1 cancer detection.

Ultra-small molybdenum-based nanodots as an antioxidant platform for effective treatment of periodontal disease

Periodontal disease (PD) is a local inflammatory disease with high morbidity, manifesting tissue destruction results from inflammation of the host immune response to bacterial antigens and irritants. The supportive function of connective tissue and skeletal tissue can be jeopardized without prompt and effective intervention, representing the major cause of tooth loss. However, traditional treatments exhibited great limitations, such as low efficacies, causing serious side effects and recurrent inflammatory episodes. As a major defense mechanism, reactive oxygen species (ROS) play important roles in the pathological progression of PD. Antioxidant therapy is widely believed to be an effective strategy for ROS-triggered diseases, including oxidative stress-induced PD. Most antioxidants can only scavenge one or a few limited kinds of ROS and cannot handle all kinds. In addition, current antioxidant nanomaterials present limitations associated with toxicity, low stability, and poor biocompatibility. To this end, we develop ultra-small molybdenum-based nanodots (MoNDs) with strong ROS in oxidative stress-induced PD. To the best of our knowledge, this is the first time that MoNDs have been used for PD. In the present study, MoNDs have shown extremely good therapeutic effects as ROS scavengers. Spectroscopic and in vitro experiments provided strong evidence for the roles of MoNDs in eliminating multiple ROS and inhibiting ROS-induced inflammatory responses. In addition, the mouse model of PD was established and demonstrated the feasibility of MoNDs as powerful antioxidants. It can alleviate periodontal inflammation by scavenging multiple ROS without obvious side effects and exhibit good biocompatibility. Thus, this newly developed nanomedicine is effective in scavenging ROS and inhibiting M1 phenotypic polarization, which provides promising candidates for the treatment of PD.

Spectroscopic, Crystallographic, and Electrochemical Study of Different Manganese(II)‐Substituted Keggin‐Type Phosphomolybdates

Adjusting the RedOx activity of polyoxometalate catalysts is a key challenge for the catalysis of selective oxidation reactions. For this purpose, the possibility of influencing the RedOx potential by the introduction of an additional RedOx‐active element was investigated. Thereby, Keggin‐type polyoxometalates (POMs) with up to three different elements in the metal framework were created. An advanced and reproducible synthetic procedure to incorporate Mn^II and additionally V^V into Keggin‐type heteropolyacids alongside comprehensive characterization of the new molecules is presented. The success of our syntheses was confirmed by vibrational spectroscopy (IR and Raman) and elemental analysis. Furthermore, the new compounds were analyzed by NMR spectroscopy to investigate the characteristics of the POMs in solution. The structures of successfully crystalized compounds were determined by single‐crystal X‐ray diffraction. Moreover, all synthesized compounds were characterized using UV/Vis spectroscopy and electrochemical analysis to get further insights into the electronic transfer processes and redox potentials.

New Organic-Inorganic Hybrid Compounds Based on Sodium Peroxidomolybdates (VI) and Derivatives of Pyridine Acids: Structure Determination and Catalytic Properties

Two organic-inorganic hybrids based on sodium peroxidomolybdates(VI) and 3,5-dicarboxylic pyridine acid (Na-35dcpa) or N-oxide isonicotinic acid (Na-isoO) have been synthesized and characterized. All compounds contain inorganic parts: a pentagonal bipyramid with molybdenum center, and an organic part containing 3,5-dicarboxylic pyridine acid or N-oxide isonicotinic acid moieties. The type of organic part used in the synthesis influences the crystal structure of obtained compounds. This aspect can be interesting for crystal engineering. Crystal structures were determined using powder X-ray diffraction or single crystal diffraction for compounds Na-35dcpa and Na-isoO, respectively. Elemental analysis was used to check the purity of the obtained compounds, while X-ray Powder Diffraction (XRPD) vs. temp. was applied to verify their stability. Moreover, all the compounds were examined by Infrared (IR) spectroscopy. Their catalytic activity was tested in the Baeyer-Villiger (BV) oxidation of cyclohexanone to ε-caprolactone in the oxygen-aldehyde system. The highest catalytic activity in the BV oxidation was observed for Na-35dcpa. The compounds were also tested for biological activity on human normal cells (fibroblasts) and colon cancer cell lines (HT-29, LoVo, SW 620, HCT 116). All compounds were cytotoxic against tumor cells with metastatic characteristics, which makes them interesting and promising candidates for further investigations of specific anticancer mechanisms.

Hybrid Ag nanoparticles/polyoxometalate-polydopamine nano-flowers loaded chitosan/gelatin hydrogel scaffolds with synergistic photothermal/chemodynamic/Ag+ anti-bacterial action for accelerated wound healing

Bacterial infections significantly slow the wound healing process, thus severely threatening human health. Furthermore, traditional antibiotics may promote the development of multidrug-resistant bacteria. Therefore, developing novel bactericides and therapeutic strategies for bacterial infections is important to enhance wound healing. Herein, a three-in-one bactericidal flower-like nanocomposite was assembled using Ag nanoparticles/phosphotungstic acid-polydopamine nano-flowers (AgNPs/POM-PDA). The nanocomposite exhibited photothermal therapy (PTT) when exposed to NIR light via photothermal conversion by PDA. The resultant photothermal effect accelerated and controlled the Ag⁺ released from AgNPs. The chemodynamic therapy (CDT) was obtained via POM catalytic Fenton-like reaction. The combined PTT/CDT/Ag⁺ treatment achieved excellent synergistic anti-bacterial activity against both gram-negative E. coli and gram-positive S. aureus. A multifunctional wound dressing was then obtained by embedding the AgNPs/POM-PDA flower-like nanocomposite into the chitosan (CS)/gelatin (GE) biocomposite hydrogel. The synergy of AgNPs/POM-PDA nanocomposites and CS/GE hydrogel remarkably accelerated wound healing in vivo due to the excellent biocompatibility, hydroabsorptivity, and breathability of the hydrogel. In this study, a multifunctional agent was developed to synergistically combat bacterial infections and accelerate wound healing.

K5BW12O40 Induces the Apoptosis of A549 Cells by Regulating Caspase-3

Objective. The purpose of the study is to explore the effect of K5BW12O40, a polyoxometalate (POM), on the apoptosis of A549 cells and its underlying mechanism and to analyze the potential therapeutic effect of K5BW12O40 in non-small-cell lung cancer. Materials and Methods. A549 cells were treated with different concentrations of K5BW12O40 (0 mg/ml, 0.001 mg/ml, 0.01 mg/ml, and 0.1 mg/ml). The proliferation of A549 cells treated with different concentrations of K5BW12O40 was detected by MTT assay (3-(4,5-dimethylthiazol-2-yl)-2 and 5-diphenyl tetrazolium bromide). The apoptosis of A549 cells induced by K5BW12O40 was detected by flow cytometry. Western blot was used to detect the changes in Bax and caspase-3 protein levels in A549 cells induced by K5BW12O40. Results. As the dose of the K5BW12O40 increases, the cell viability of A549 cells gradually decreases. The results of flow cytometry showed that the apoptotic rate of A549 cells increased with the increase of K5BW12O40 concentration. Western blot results showed that the expression of the apoptosis marker protein caspase-3 was increased in the three groups treated with K5BW12O40 whereas the protein level of Bax did not change significantly in A549 cells treated with K5BW12O40. Conclusions. K5BW12O40 increases the apoptotic rate of A549 cells by upregulating caspase-3.

Enhanced dual-band modulation of visible and near-infrared light transmittance in electrochromic composite films based on Preyssler-type polyoxometalates and W18O49

Benefitting from a unique wrap-type porous nano-structure, a POM/W18O49 composite film achieved excellent electrochromic properties and a high coloration efficiency, and is promising for applications in smart windows.

A POM-based copper-coordination polymer crystal material for phenolic compound degradation by immobilizing horseradish peroxidase

A new polyoxometalate (POM)-based organic-inorganic hybrid Cu-coordination polymer, namely {((Cu(bipy))₂(μ-PhPO₃)₂Cu(bipy))₂H(PCuW₁₁O₃₉)·3H₂O}_n (denoted as compound 1, bipy = 2,2'-bipyridine, PhPO₃ = phenylphosphonate), was self-assembled hydrothermally. Single-crystal X-ray diffraction (SC-XRD) analysis shows that two unique types of 1D chains are present in compound 1, i.e. Cu(II)-organophosphine and organonitrogen complex cation ([((Cu(bipy))₂(μ-PhPO₃)₂Cu(bipy))₂]⁴⁺) chains and Cu-monosubstituted Keggin-type polyoxoanion ([PCuW₁₁O₃₉]^5-) chains, forming a hetero-POM. Crystalline compound 1 as a new enzyme immobilization support exhibited a high horseradish peroxidase (HRP) loading capacity (268 mg g^-1). The powder X-ray diffraction (PXRD), FTIR, zeta potential, confocal laser scanning microscopy (CLSM) and circular dichroism (CD) results show that HRP is only immobilized on the surface of compound 1 through simple physical adsorption without a secondary structure change. This POM-immobilized enzyme (HRP/1) was first used for degradation of pollutants in wastewater, and it showed a high degradation efficiency and TOC removal efficiency for phenol, 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) within 30 min reaction time. Moreover, HRP/1 exhibited better operational and storage stabilities and reusability compared with free HRP. This work suggests that POMs can be used as new supports for enzyme immobilization and POM-immobilized enzymes may be used as a new kind of biocatalyst for degradation of phenolic pollutants.

Looking for Options to Sustainably Fixate Nitrogen. Are Molecular Metal Oxides Catalysts a Viable Avenue?

Fast and reliable industrial production of ammonia (NH₃) is fundamentally sustaining modern society. Since the early 20^th Century, NH₃ has been synthesized via the Haber-Bosch process, running at conditions of around 350-500°C and 100-200 times atmospheric pressure (15-20 MPa). Industrial ammonia production is currently the most energy-demanding chemical process worldwide and contributes up to 3% to the global carbon dioxide emissions. Therefore, the development of more energy-efficient pathways for ammonia production is an attractive proposition. Over the past 20 years, scientists have imagined the possibility of developing a milder synthesis of ammonia by mimicking the nitrogenase enzyme, which fixes nitrogen from the air at ambient temperatures and pressures to feed leguminous plants. To do this, we propose the use of highly reconfigurable molecular metal oxides or polyoxometalates (POMs). Our proposal is an informed design of the polyoxometalate after exploring the catabolic pathways that cyanobacteria use to fix N₂ in nature, which are a different route than the one followed by the Haber-Bosch process. Meanwhile, the industrial process is a "brute force" system towards breaking the triple bond N-N, needing high pressure and high temperature to increase the rate of reaction, nature first links the protons to the N₂ to later easier breaking of the triple bond at environmental temperature and pressure. Computational chemistry data on the stability of different polyoxometalates will guide us to decide the best design for a catalyst. Testing different functionalized molecular metal oxides as ammonia catalysts laboratory conditions will allow for a sustainable reactor design of small-scale production.

Selected polyoxopalladates as promising and selective antitumor drug candidates

Polyoxo-noble-metalates (PONMs), a class of molecular noble metal-oxo nanoclusters that combine features of both polyoxometalates and noble metals, are a promising platform for the development of next-generation antitumor metallodrugs. This study aimed to evaluate the antitumor potential against human neuroblastoma cells (SH-SY5Y), as well as toxicity towards healthy human peripheral blood cells (HPBCs), of five polyoxopalladates(II): (Na₈[Pd₁₃As₈O₃₄(OH)₆]·42H₂O (Pd₁₃), Na₄[SrPd₁₂O₆(OH)₃(PhAsO₃)₆(OAc)₃]·2NaOAc·32H₂O (SrPd₁₂), Na₆[Pd₁₃(AsPh)₈O₃₂]·23H₂O (Pd₁₃L), Na₁₂[SnO₈Pd₁₂(PO₄)₈]·43H₂O (SnPd₁₂), and Na₁₂[PbO₈Pd₁₂(PO₄)₈]·38H₂O (PbPd₁₂)), as the largest subset of PONMs. A pure inorganic, Pd₁₃, was found as the most potent and selective antineuroblastoma agent with IC₅₀ values (µM) of 7.2 ± 2.2 and 4.4 ± 1.2 for 24 and 48 h treatment, respectively, even lower than cisplatin (28.4 ± 7.4 and 11.6 ± 0.8). The obtained IC₅₀ values (µM) for 24/48 h treatment with SrPd₁₂ and Pd₁₃L were 75.8 ± 6.7/76.7 ± 22.9 and 63.8 ± 3.6/21.4 ± 10.8, respectively, whereas SnPd₁₂ and PbPd₁₂ did not remarkably affect the SH-SY5Y viability (IC₅₀ > > 100 µM). Pd₁₃ caused depolarisation of inner mitochondrial membrane prior to superoxide ion hyperproduction, followed by caspase activation, DNA fragmentation and cell cycle arrest, all hallmarks of apoptotic cell death, and accompanied by an increase in acidic vesicles content, suggestive of autophagy induction. Importantly, Pd₁₃ demonstrated the antitumor effect at concentrations not cytogenotoxic for normal HPBCs. On the contrary, SrPd₁₂ and Pd₁₃L at concentrations ≥ 1/3 IC₅₀ (24 h) decreased HPBC viability and increased % tail DNA up to 42% and 3.05 times, respectively, related to control. SnPd₁₂ and PbPd_12, previously confirmed promising antileukemic agents, did not exhibit cytogenotoxicity to HPBCs, and thus could be regarded as tumor cell specific and selective drug candidates.