Functionalization of Siloxanes with Arynes Generated from o-Triazenylarylboronic Acids.

Herein, we report the functionalization of polyhedral oligosilsesquioxanes (POSS) and related siloxanes with arynes. Using o-triazenylarylboronic acids as aryne precursors and silica gel as the activator, the transformation of siloxane bearing various arynophilic moieties on the side chains was achieved with high yields without touching the siloxane core. This method was applied to the conjugation of POSS and pharmaceutical cores using an aryne derived from the synthetic intermediate of cabozantinib. Furthermore, orthogonal dual functionalization of POSS was realized by combining the aryne reaction with Huisgen cyclization.

Fluorescent biosensor based on magnetic separation platform and spore-like breakable organosilica nanocapsules controlled-release carbon dots for the detection of Escherichia coli O157:H7.

Ultrasensitive and rapid detection of low concentration of Escherichia coli O157: H7 (E. coli O157:H7) in food is essential for food safety and public health. In this study, A novel fluorescence signal amplification biosensor based on magnetic separation platform and red fluorescent carbon dots (R-CDs)-encapsulated breakable organosilica nanocapsules (BONs) for ultrasensitive detection of E. coli O157:H7 was established. Wulff-type boronic acid functionalized magnetic nanoparticles (MNPs@B-N/APBA) with broad-spectrum bacterial recognition ability were synthesized for the first time to recognize and capture E. coli O157: H7 in food samples. R-CDs@BONs labeled with anti-E. coli O157:H7 monoclonal antibody (mAb@R-CDs@BONs-NH2) were used as the second recognition element to ensure the specificity for E. coli O157:H7 and form MNPs@B-N/APBA∼ E. coli O157:H7∼mAb@R-CDs@BONs-NH2 sandwich complexes, followed by releasing R-CDs to generate amplified fluorescence response signals for quantitative detection of E. coli O157:H7. The proposed method had a limit of detection with 25 CFU/mL in pure culture and contaminated lettuce samples, which the whole detection process took about 120 min. This fluorescence signal amplification biosensor has the potential to detect other pathogens in food by altering specific antibodies.

Monitoring of singlet oxygen generation of a novel Schiff-base substituted silicon phthalocyanines by sono-photochemical studies and in vitro activities on prostate cancer cell.

This study demonstrates the potential of sono-photodynamic therapy as an effective approach for enhancing singlet oxygen generation using the synthesized Schiff-base diaxially substituted silicon phthalocyanines. In photochemical studies, the singlet oxygen quantum yields (Φ∆) were determined as 0.43 for Si1a, 0.94 for Q-Si1a, 0.58 for S-Si1a, and 0.49 for B-Sia1. In sono-photochemical studies, the Φ∆ values were reached to 0.67 for Si1a, 1.06 for Q-Si1a, 0.65 for S-Si1a, and 0.67 for B-Sia1. In addition, this study demonstrates the therapeutic efficacy of phthalocyanines synthesized as sensitizers on the PC3 prostate cancer cell line through in vitro experiments. The application of these treatment modalities exhibited notable outcomes, leading to a substantial decrease in cell viability within the PC3 prostate cancer cell line. These findings highlight the potential of utilizing these synthesized phthalocyanines as promising therapeutic agents for prostate cancer treatment.

Magnetically modified-mitoxantrone mesoporous organosilica drugs: an emergent multimodal nanochemotherapy for breast cancer.

BACKGROUND: Chemotherapy, the mainstay treatment for metastatic cancer, presents serious side effects due to off-target exposure. In addition to the negative impact on patients' quality of life, side effects limit the dose that can be administered and thus the efficacy of the drug. Encapsulation of chemotherapeutic drugs in nanocarriers is a promising strategy to mitigate these issues. However, avoiding premature drug release from the nanocarriers and selectively targeting the tumour remains a challenge. RESULTS: In this study, we present a pioneering method for drug integration into nanoparticles known as mesoporous organosilica drugs (MODs), a distinctive variant of periodic mesoporous organosilica nanoparticles (PMOs) in which the drug is an inherent component of the silica nanoparticle structure. This groundbreaking approach involves the chemical modification of drugs to produce bis-organosilane prodrugs, which act as silica precursors for MOD synthesis. Mitoxantrone (MTO), a drug used to treat metastatic breast cancer, was selected for the development of MTO@MOD nanomedicines, which demonstrated a significant reduction in breast cancer cell viability. Several MODs with different amounts of MTO were synthesised and found to be efficient nanoplatforms for the sustained delivery of MTO after biodegradation. In addition, Fe3O4 NPs were incorporated into the MODs to generate magnetic MODs to actively target the tumour and further enhance drug efficacy. Importantly, magnetic MTO@MODs underwent a Fenton reaction, which increased cancer cell death twofold compared to non-magnetic MODs. CONCLUSIONS: A new PMO-based material, MOD nanomedicines, was synthesised using the chemotherapeutic drug MTO as a silica precursor. MTO@MOD nanomedicines demonstrated their efficacy in significantly reducing the viability of breast cancer cells. In addition, we incorporated Fe3O4 into MODs to generate magnetic MODs for active tumour targeting and enhanced drug efficacy by ROS generation. These findings pave the way for the designing of silica-based multitherapeutic nanomedicines for cancer treatment with improved drug delivery, reduced side effects and enhanced efficacy.

Multifunctional Hierarchical Nanoplatform with Anisotropic Bimodal Mesopores for Effective Neural Circuit Reconstruction after Spinal Cord Injury.

A persistent inflammatory response, intrinsic limitations in axonal regenerative capacity, and widespread presence of extrinsic axonal inhibitors impede the restoration of motor function after a spinal cord injury (SCI). A versatile treatment platform is urgently needed to address diverse clinical manifestations of SCI. Herein, we present a multifunctional nanoplatform with anisotropic bimodal mesopores for effective neural circuit reconstruction after SCI. The hierarchical nanoplatform features of a Janus structure consist of dual compartments of hydrophilic mesoporous silica (mSiO2) and hydrophobic periodic mesoporous organosilica (PMO), each possessing distinct pore sizes of 12 and 3 nm, respectively. Unlike traditional hierarchical mesoporous nanomaterials with dual-mesopores interlaced with each other, the two sets of mesopores in this Janus nanoplatform are spatially independent and possess completely distinct chemical properties. The Janus mesopores facilitate controllable codelivery of dual drugs with distinct properties: the hydrophilic macromolecular enoxaparin (ENO) and the hydrophobic small molecular paclitaxel (PTX). Anchoring with CeO2, the resulting mSiO2&PMO-CeO2-PTX&ENO nanoformulation not only effectively alleviates ROS-induced neuronal apoptosis but also enhances microtubule stability to promote intrinsic axonal regeneration and facilitates axonal extension by diminishing the inhibitory effect of extracellular chondroitin sulfate proteoglycans. We believe that this functional dual-mesoporous nanoplatform holds significant potential for combination therapy in treating severe multifaceted diseases.

SilE-R and SilE-S-DABB Proteins Catalying Enantiospecific Hydrolysis of Organosilyl Ethers.

Silyl ethers fulfil a fundamental role in synthetic organic chemistry as protecting groups and their selective cleavage is an important factor in their application. We present here for the first time two enzymes, SilE-R and SilE-S, which are able to hydrolyse silyl ethers. They belong to the stress-response dimeric A/B barrel domain (DABB) family and are able to cleave the Si-O bond with opposite enantiopreference. Silyl ethers containing aromatic, cyclic or aliphatic alcohols and, depending on the alcohol moiety, silyl functions as large as TBDMS are accepted. The X-ray crystal structure of SilE-R, determined to a resolution of 1.98 Å, in combination with mutational studies, revealed an active site featuring two histidine residues, H8 and H79, which likely act synergistically as nucleophile and Brønsted base in the hydrolytic mechanism, which has not previously been described for enzymes. Although the natural function of SilE-R and SilE-S is unknown, we propose that these 'silyl etherases' may have significant potential for synthetic applications.

Organosilica Nanosensors for Monitoring Spatiotemporal Changes in Oxygen Levels in Bacterial Cultures.

Oxygen plays a central role in aerobic metabolism, and while many approaches have been developed to measure oxygen concentration in biological environments over time, monitoring spatiotemporal changes in dissolved oxygen levels remains challenging. To address this, we developed a ratiometric core-shell organosilica nanosensor for continuous, real-time optical monitoring of oxygen levels in biological environments. The nanosensors demonstrate good steady state characteristics (KpSV = 0.40 L/mg, R2 = 0.95) and respond reversibly to changes in oxygen concentration in buffered solutions and report similar oxygen level changes in response to bacterial cell growth (Escherichia coli) in comparison to a commercial bulk optode-based sensing film. We further demonstrated that the oxygen nanosensors could be distributed within a growing culture of E. coli and used to record oxygen levels over time and in different locations within a static culture, opening the possibility of spatiotemporal monitoring in complex biological systems.

AgNPs loaded adenine-modified chitosan composite POSS-PEG hybrid hydrogel with enhanced antibacterial and cell proliferation properties for promotion of infected wound healing.

Wound healing is a dynamic and complex process, it's urgent to develop new wound dressings with excellent performance to promote wound healing at the different stages. Here, a novel composite hydrogel dressing composed by silver nanoparticles (AgNPs) impregnated adenine-modified chitosan (CS-A) and octafunctionalized polyhedral oligomeric silsesquioxane (POSS) of benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO) solution was presented to solve the problem of wound infection. Modification of chitosan with adenine, not only can improve the water solubility of chitosan, but also introduce bioactive substances to promote cell proliferation. CS-A and POSS-PEG-CHO were cross-linked by Schiff-base reaction to form the injectable self-healing hydrogel. On this basis, AgNPs were added into the hydrogel, which endows the hydrogel with better antibacterial activity. Moreover, this kind of hydrogel exhibits excellent cell proliferation properties. Studies demonstrated that the hydrogel can significantly accelerate the closure of infected wounds. The histological analysis and immunofluorescence staining demonstrated that the wounds treated with the composite hydrogel exhibited fewer inflammatory cells, more collagen deposition and angiogenesis, faster regeneration of epithelial tissue. Above all, adenine-modified chitosan composite hydrogel with AgNPs loaded was considered as a dressing material with great application potential for promoting the healing of infected wounds.

Properties of chromatographic columns prepared on the basis of poly(1-trimethylsilyl-1-propyne) modified with organic bases.

This article describes the effect of modification with organic bases such as uracil (U) and polyethyleneimine (PEI) on the adsorption and chromatographic properties of poly(1-trimethylsilyl-1-propyne) (PTMSP) used as a stationary phase (SP) in packed and capillary columns. It was shown that the sorbents prepared on the basis of diatomite Chromosorb P NAW support and successively modified with 9 wt.% PTMSP and 1 wt.% U (or PEI) (PC-U and PC-PEI samples, respectively), have a mesoporous structure. The IR spectrum shows the presence of carbonyl groups in the sorbent modified with uracil. The impregnation of the Chromosorb P NAW + (9/1) wt.% PTMSP sorbent with a polyethyleneimine solution leads to the appearance in the spectrum of bands characterizing NH stretching and bending vibrations, as well as a band at 1310 cm-1 which can be attributed to CN bond vibrations. The chromatographic properties of the studied sorbents differ significantly from the properties of the initial PTMSP. Packed columns PC-U and PC-PEI, as well as capillary columns with a polyethyleneimine-modified PTMSP layer, allow one to selectively separate mixtures of polar and non-polar compounds and structural isomers of hydrocarbons. Methanol on these columns is eluted in the form of a symmetrical peak separately from propane, propylene and other associated hydrocarbon impurities in commercial (technical, target) n-butane.

Asymmetric silicon phthalocyanine based nanoparticle with spatiotemporally targeting of mitochondria for synergistic apoptosis-ferroptosis antitumor treatment.

A promising therapeutic strategy in cancer treatment merges photodynamic therapy (PDT) induced apoptosis with ferroptosis, a form of programmed cell death governed by iron-dependent lipid peroxidation. Given the pivotal role of mitochondria in ferroptosis, the development of photosensitizers that specifically provoke mitochondrial dysfunction and consequentially trigger ferroptosis via PDT is of significant interest. To this end, we have designed and synthesized a novel nanoparticle, termed FECTPN, tailored to address this requisite. FECTPN harnesses a trifecta of critical attributes: precision mitochondria targeting, photoactivation capability, pH-responsive drug release, and synergistic apoptosis-ferroptosis antitumor treatment. This nanoparticle was formulated by conjugating an asymmetric silicon phthalocyanine, Chol-SiPc-TPP, with the ferroptosis inducer Erastin onto a ferritin. The Chol-SiPc-TPP is a chemically crafted entity featuring cholesteryl (Chol) and triphenylphosphine (TPP) functionalities bonded axially to the silicon phthalocyanine, enhancing mitochondrial affinity and leading to effective PDT and subsequent apoptosis of cells. Upon cellular uptake, FECTPN preferentially localizes to mitochondria, facilitated by Chol-SiPc-TPP's targeting mechanics. Photoactivation induces the synchronized release of Chol-SiPc-TPP and Erastin in the mitochondria's alkaline domain, driving the escalation of both ROSs and lipid peroxidation. These processes culminate in elevated antitumor activity compared to the singular application of Chol-SiPc-TPP-mediated PDT. A notable observation is the pronounced enhancement in glutathione peroxidase-4 (GPX4) expression within MCF-7 cells treated with FECTPN and subjected to light exposure, reflecting intensified oxidative stress. This study offers compelling evidence that FECTPN can effectively induce ferroptosis and reinforces the paradigm of a synergistic apoptosis-ferroptosis pathway in cancer therapy, proposing a novel route for augmented antitumor treatments.

POSS and PEG Contained Copolymer for Antibioadhesive Rigid Contact Lenses Materials Application.

Myopia is a global public health issue. Rigid contact lenses (RCLs) are an effective way to correct or control myopia. However, bioadhesion issues remain one of the significant obstacles limiting its clinical application. Although enhancing hydrophilicity through various surface treatments can mitigate this problem, the duration of effectiveness is short-lived and the processing involved is complex and costly. Herein, an antiadhesive RCLs material was designed via 8-armed methacrylate-POSS (8MA-POSS), and poly(ethylene glycol) methacrylate (PEGMA) copolymerization with 3-[tris(trimethylsiloxy)silyl] propyl methacrylate (TRIS). The POSS and PEG segments incorporated P(TRIS-co-PEGMA-co-8MA-POSS) (PTPM) material was obtained and their optical transparency, refractive index, resolution, hardness, surface charge, thermal features, and wettability were tested and optimized. The antibioadhesion activities, including protein, lipid, and bacteria, were evaluated as well. In vitro and in vivo results indicated that the optimized antibioadhesive PTPM materials present good biocompatibility and biosafety. Thus, such POSS and PEG segments containing material were a potential antibioadhesive RCL material option.

A novel polyhedral oligomeric silsesquioxane nanohybrid fluorescent sensor designed based on an osmotic mechanism for specific detection and intelligent scavenging of magnesium ions.

BACKGROUND: Mg2+ has long been recognized as one of the most vital cations due to its diverse physiological and pathological roles, making it indispensable in both biomedical and biological research. Organic fluorescent sensors are commonly employed for Mg2+ detection, but they often lack high selectivity and exhibit poor hydrophilicity, limiting their biomedical applications. RESULTS: Herein, we introduced a novel organic-inorganic hybrid fluorescence sensor, PFHBS, constructed on the POSS nanoplatforms. The efficient connection between PEGylated POSS and the small molecule sensor FHBS through Click chemistry enhances the selectivity and reduces interference, making this chemical sensor ideal for the accurate detection of Mg2+. Furthermore, the incorporation of POSS amplifies the ligand field effect of FHBS, making it more conducive to Mg2+ capture. The modification of PEG chains enhances the sensor's amphiphilicity, facilitating efficient cell penetration and effective Mg2+ detection at the biological level. SIGNIFICANCE: Finally, relying on spontaneous permeation, coupled with its strong ligand field effect and excellent cell permeability, the chemosensor demonstrates the capability to intelligently remove excess Mg2+ from the body. It has been successfully applied to mitigate renal overload resulting from acute Mg2+ poisoning.

One-pot preparation of bi-functional POSS-based hybrid monolith via photo-initiated polymerization for isolation of extracellular vesicles.

Extracellular vesicles (EVs) are important participants in numerous pathophysiological processes, and could be used as valuable biomarkers to detect and monitor various diseases. However, facile EV isolation methods are the essential and preliminary issue for their downstream analysis and function investigation. In this work, a polyhedral oligomeric silsesquioxanes (POSS) based hybrid monolith combined metal affinity chromatography (MAC) and distearoyl phospholipid ethanolamine (DSPE) function was developed via photo-initiated thiol-ene polymerization. This synthesis process was facile, simple and convenient, and the obtained hybrid monolith could be applied to efficiently isolate EVs from bio-samples by taking advantages of the specific bond of Ti4+ and phosphate groups on the phospholipid membrane of EVs and the synergistic effect of DSPE insertion. Meanwhile, the eluted EVs could maintain their structural integrity and biological activity, suggesting they could be used for downstream application. Furthermore, 75 up-regulated proteins and 56 down-regulated proteins were identified by comparing the urinary EVs of colorectal cancer (CRC) patients and healthy donors, and these proteins might be used as potential biomarkers for early screening of CRC. These results demonstrated that this hybrid monolith could be used as a simple and convenient tool for isolating EVs from bio-samples and for wider applications in biomarker discovery.

Ni(II) functionalized polyhedral oligomeric silsesquioxane based capillary monolith for purification of histidine-tagged proteins by immobilized metal affinity micro-chromatography.

A new capillary monolithic stationary phase was synthesized for the purification of histidine tagged proteins by immobilized metal affinity micro-chromatography (µ-IMAC). For this purpose, mercaptosuccinic acid (MSA) linked-polyhedral oligomeric silsesquioxane [MSA@poly(POSS-MA)] monolith 300 µm in diameter was obtained by thiol-methacrylate polymerization using methacryl substituted-polyhedral oligomeric silsesquioxane (POSS-MA) and MSA as the thiol functionalized agent in a fused silica capillary tubing. Ni(II) cations were immobilized onto the porous monolith via metal-chelate complex formation with double carboxyl functionality of bound MSA segments. µ-IMAC separations aiming the purification of histidine tagged-green fluorescent protein (His-GFP) from Escherichia coli extract were carried out on Ni(II)@MSA functionalized-poly(POSS-MA) [Ni(II)@MSA@poly(POSS-MA)] capillary monolith. His-GFP was succesfully isolated by µ-IMAC on Ni(II)@MSA@poly(POSS-MA) capillary monolith with the isolation yield of 85 % and the purity of 92 % from E. coli extract. Higher His-GFP isolation yields were obtained with lower His-GFP feed concentrations and lower feed flow rates. The monolith was used for consecutive His-GFP purifications with a tolerable decrease in equilibrium His-GFP adsorption over five runs.

Periodic Mesoporous Organosilica Nanomaterials with Unconventional Structures and Properties.

Periodic mesoporous organosilicas (PMOs) are high surface area organic-inorganic hybrid nanomaterials that have found broad applications in various fields of research such as in (bio)chemistry or material science. By choosing suitable organic groups in the framework of these materials, their surface properties such as polarity, optical/electrical characteristics and adsorption capacity can be tuned. This critical review provides an overview of the current state of the art in the developments and applications of some PMO nanomaterials in diverse fields of research. This is placed in the context of four leading areas of PMO nanomaterials, including chiral PMOs, plugged PMO nanomaterials, Janus PMOs and PMO-based nanomotors. The review briefly discusses the recent and key findings on these PMO nanomaterials as well as their potential applications for future developments.

Effect of Axial Ligand Length on Biological and Anticancer Properties of Axially Disubstituted Silicon Phthalocyanines.

In this study, three new axially disubstituted silicon phthalocyanines (SiPc1-3) and their quaternized phthalocyanine derivatives (QSiPc1-3) were prepared and characterized. The biological properties (antioxidant, antimicrobial, antibiofilm, and microbial cell viability activities) of the water-soluble silicon phthalocyanines were examined, as well. A 1 % DMSO diluted with pure water was used as a solvent in biological activity studies. All the compounds exhibited high antioxidant activity. They displayed efficient antimicrobial and antimicrobial photodynamic therapeutic properties against various microorganisms, especially Gram (+) bacteria. Additionally, they demonstrated high antibiofilm activities against S. aureus and P. aeruginosa. In addition, 100 % bacterial reduction was obtained for all the studied phthalocyanines against E. coli viable cells. Besides, the DNA cleavage and binding features of compounds (QSiPc1-3) were studied using pBR322 DNA and CT-DNA, respectively. Furthermore, the human topoisomerase I enzyme inhibition activities of compounds QSiPc1-3 were studied. Anticancer properties of the water-soluble compounds were investigated using cell proliferation MTT assay. They exhibited anticarcinogenic activity against the human colon cancer cell line (DLD-1). Compounds QSiPc1 and QSiPc3 displayed a high anticarcinogenic effect on the DLD-1 cell line. The obtained results indicated that all the studied compounds may be effective biological agents and anticancer drugs after further investigations.

Preparation and application of sulfated lily polysaccharide bridged polyhedral oligomeric silsesquioxane hybrid organosilicas as stationary phase.

Periodic mesoporous organosilicas (PMO) hydrophilic microspheres were synthesized by co-condensation of sulfated polysaccharide from Lilum lancifolium Thunb. bridged silane (SLLTPBS) and polyhedral oligomeric silsesquioxane (POSS) as stationary phase (PMO(SLLTP-POSS)) for per aqueous liquid chromatography (PALC), which would overcome the disadvantages of using a large amount of acetonitrile on the hydrophilic interaction liquid chromatography (HILIC) columns. Average particle size of PMO (SLLTP-POSS) microspheres was 4.9 µm, which was suitable for stationary phase. The retention mechanism of the stationary phase in PALC was mainly hydrophobic interactions and also included some ion-exchange interactions and electrostatic interactions. The acid-base resistance was greatly improved compared to the C18 column. The PMO(SLLTP-POSS) column under PALC mode had increased the resolution when separating some hydrophilic compounds such as eight organic acids and eleven sweeteners compared with the C18 column and HILIC column. The new column was more efficient than the HILIC columns. Additionally, a PALC-triple quadrupole mass spectrometry approach for the simultaneous identification of the eleven sweeteners was developed. The averagere coveries of the eleven compounds were 70.20%-91.33% with the relative standard deviation (RSD) range of 1.74% to 4.27%. The results showed good precision and accuracy of the method.

Swellable hollow periodic mesoporous organosilica capsules with ultrahigh loading capacity for hydrophobic drugs.

As a new kind of drug carrier, practical applications of hollow periodic mesoporous organosilica (HPMO) have been greatly limited by their low loading capacity for hydrophobic drugs. In this work, we demonstrated the preparation of HPMO capsules with tunable shell thickness by using 1,2-bis(triethoxysilyl)ethane as the precursor. The capsules with thin shells and thus low Young's modulus showed excellent swellability to organic solvents containing hydrophobic drugs. As a result, hydrophobic drugs, i.e., paclitaxel (PTX) could be loaded into the hollow interior of the HPMO capsules with 4 nm shell at an efficiency of ca. 120 %. The as-prepared PTX-loaded HPMO capsules were dispersible in aqueous media and showed improved performance in killing cancer cells compared to free PTX.

Regioisomeric Giant Triblock Molecules: Role of the Linker.

In this study, polyhedral oligomeric silsesquioxane (POSS) based giant triblock molecules with precisely defined regio-configuration are modularly prepared through highly efficient coupling reactions. The length of the linker connecting neighboring nanoparticles is elaborately designed to regulate the geometric constraints. The triblock molecules adopt a folded packing during phase separation, and the regio-configuration imparts direct influence on the self-assembly behaviors. The ortho-isomers form periodic structures with a larger domain size, larger interfacial curvature, and enhanced phase stability. The regio-effect is closely related to the length and symmetry of the linker. As the linker extends, the neighboring particles gradually decouple, and the regio-effect diminishes. The symmetry of the linker shows an even more profound impact. This work quantitatively scrutinized the role of the linker, opening an avenue for engineering the assembled structures with molecular precision.

Ru- and Ir-complex decorated periodic mesoporous organosilicas as sensitizers for artificial photosynthesis.

A versatile and facile strategy based on an inverse electron demand Diels-Alder reaction between 5-norbornen-2-yltriethoxysilane and a tetrazine derivative has been established for the synthesis of a new triethoxysilane precursor containing dipyridylpyridazine units. Such a precursor has been incorporated into the mesostructure of an ethylene-bridged periodic mesoporous organosilica (PMO) material through a one-pot synthesis via a co-condensation method. Upon attachment of Ru- and Ir-complexes to the pendant N-chelating heterocyclic ligands, the resulting decorated PMOs have acted as photosensitizers in artificial photosynthetic systems. The deposition of Pt on these PMOs has allowed us to obtain efficient photocatalytic materials for the hydrogen evolution reaction as a result of electron transfer from the light harvesting Ru- and Ir-complexes to the supported Pt nanoparticles through methyl viologen as an electron relay. They have exhibited total turnover number values of 573 and 846, respectively, under visible light irradiation. The role played by each component and the stability of the photocatalytic systems have been discussed. The present approach paves the way to the synthesis of different materials with coordination sites capable of forming surface complexes to be applied as sensitizers and catalysts.