Development and Application of an Advanced Biomedical Material-Silk Sericin.

Sericin, a protein derived from silkworm cocoons, is considered a waste product derived from the silk industry for thousands of years due to a lack of understanding of its properties. However, in recent decades, a range of exciting properties of sericin are studied and uncovered, including cytocompatibility, low-immunogenicity, photo-luminescence, antioxidant properties, as well as cell-function regulating activities. These properties make sericin-based biomaterials promising candidates for biomedical applications. This review summarizes the properties and bioactivities of silk sericin and highlights the latest developments in sericin in tissue engineering and regenerative medicine. Furthermore, the extended application of sericin in developing flexible electronic devices and 3D bioprinting is also discussed. It is believed that sericin-based biomaterials have great potential of being developed into novel tissue engineering products and smart implantable devices for various medical applications toward improving clinical outcomes.

Nickel-Based Metal-Organic Frameworks Promote Diabetic Wound Healing via Scavenging Reactive Oxygen Species and Enhancing Angiogenesis.

Chronic diabetic wounds remain a worldwide challenge for both the clinic and research. Given the vicious circle of oxidative stress and inflammatory response as well as the impaired angiogenesis of the diabetic wound tissues, the wound healing process is disturbed and poorly responds to the current treatments. In this work, a nickel-based metal-organic framework (MOF, Ni-HHTP) with excellent antioxidant activity and proangiogenic function is developed to accelerate the healing process of chronic diabetic wounds. The Ni-HHTP can mimic the enzymatic catalytic activities of antioxidant enzymes to eliminate multi-types of reactive species through electron transfer reactions, which protects cells from oxidative stress-related damage. Moreover, this Ni-based MOF can promote cell migration and angiogenesis by activating transforming growth factor-ß1 (TGF-ß1) in vitro and reprogram macrophages to the anti-inflammatory phenotype. Importantly, Ni-HHTP effectively promotes the healing process of diabetic wounds by suppressing the inflammatory response and enhancing angiogenesis in vivo. This study reports a versatile and promising MOF-based nanozyme for diabetic wound healing, which may be extended in combination with other wound dressings to enhance the management of diabetic or non-healing wounds.

Nanozyme-like single-atom catalyst combined with artesunate achieves photothermal-enhanced nanocatalytic therapy in the near-infrared biowindow.

Selectively generating active free radical (AFR) in tumor microenvironment (TME) can promote irreversible oxidation of biomolecules and damage tumor cells, resulting in effective tumor inhibition. However, therapeutic efficacy of AFR-based tumor suppression approaches is often limited by insufficient amount of H2O2 or O2 within TME. To overcome this obstacle, we design a pH/photothermal dual responsive nanosystem (PFeSA@AS) for combined photothermal and nanocatalytic therapy in the near-infrared biowindow. Here the Fe single-atom dispersed N, S-doped carbon nanosheets (FeSA) nanozyme is dispersed by phospholipid-polyethylene glycol-amine (DSPE-PEG-NH2), and further loads artesunate (AS) via an amide reaction. Upon 808-nm laser irradiation in TME, the AS is released and further be catalyzed by the FeSA nanozyme to produce cytotoxic C-centered AFRs, and further be accelerated due to the photothermal conversion performance of FeSA (23.35%). The nanocatalytic process of FeSA nanozyme is realized by density functional theory (DFT). The tumor inhibition rates of a CT26 xenograft model is 92% through a photothermal-enhanced nanocatalytic synergistic therapy, and negligible systematic toxicity is observed. This work offers a potential paradigm of multifunctional single atomic catalysts (SACs) for enhancing tumor nanocatalytic therapy. STATEMENT OF SIGNIFICANCE: We designed a pH/photothermal dual responsive nanosystem (PFeSA@AS) for nanocatalytic therapy: (1) the nanosystem responsively releases AS under 808-nm laser irradiation in TME; (2) FeSA in the nanosystem can act as heme mimetic to convert AS into high cytotoxic C-centered free radicals for nanocatalytic therapy; (3) the photothermal conversion performance of FeSA further enhances the catalytic process to yield abundant AFR. Both in vitro and in vivo results demonstrate that this nanosystem can efficiently inhibit tumor growth through a photothermal-enhanced nanocatalytic synergistic therapy.

Silk sericin patches delivering miRNA-29-enriched extracellular vesicles-decorated myoblasts (SPEED) enhances regeneration and functional repair after severe skeletal muscle injury.

Severe skeletal muscle injuries usually lead to a series of poor recovery issues, such as massive myofibers loss, scar tissue formation, significant muscle function impairment, etc. Here, a silk sericin patch delivering miRNA-29-enriched extracellular vesicles-decorated myoblasts (SPEED) is designed for the rapid regeneration and functional repair after severe skeletal muscle injury. Specifically, miR29-enriched extracellular vesicles (miR29-EVs) are prepared and used to deliver miR29 into primary myoblasts, which promote the myotube formation of myoblasts and increase the expression of myogenic genes while inhibiting the expression of fibrotic genes. Our results indicate that miR29-EVs promote the integration of primary myoblasts and host muscle in a severe mouse tibialis anterior (TA) muscle injury model. Moreover, implantation of SPEED drastically stimulates skeletal muscle regeneration, inhibits fibrosis of injured muscles, and leads to significant improvement of muscle contraction forces and motor ability of mice about 3 weeks after treatment. Subsequently, we further evaluate the transcriptomes of TA muscles and find that SPEED can significantly ameliorate energy metabolism and muscular microenvironment of TA muscles on day 9 after implantation. Additionally, bioinformatic analysis and comprehensive molecular biology studies also reveal that the down-regulation of CDC20-MEF2C signaling axis may participate in the muscle repair process. Together, SPEED may serve as an effective alternative for the rapid repair of severe skeletal muscle injuries in the future.

Antibacterial Sericin Cryogels Promote Hemostasis by Facilitating the Activation of Coagulation Pathway and Platelets.

Cryogels, with high water/blood absorption, have great potential for rapid hemostasis. In this study, a hemostatic and antibacterial sericin-methacryloyl/Ag cryogel (SMC@Ag) based on freeze polymerization of methacryloyl-modified sericin and in situ reduction of silver ions is developed. The combination of interconnected micropores and Ag NPs endows the cryogel with high water/blood absorption, and outstanding hemostatic and antibacterial performance. SMC@Ag shows much better hemostatic performance than the commercial gelatin sponge in rat liver injury, tail amputation, and femoral artery injury models. Furthermore, the excellent hemostatic activity of SMC@Ag is due to facilitating the coagulation pathway activation and enhancing the platelets adhesion during coagulation process. Overall, SMC@Ag cryogel with excellent hemostatic and antibacterial performance is a suitable candidate for traumatic hemorrhage and wound healing.

Improving regorafenib's organ target precision via nano-assembly to change its delivery mode abolishes chemoresistance and liver metastasis of colorectal cancer.

Distant metastases and chemotherapy repellency are the key causes of colorectal cancer (CRC)-related mortality. Regorafenib, an oral multi-kinase inhibitor approved for treating advanced CRC with distant metastases and/or chemo-resistance, however only improves median overall survival by 1.4 months. Such limited therapeutic effect is likely due to the low bioavailability of orally administered hydrophobic regorafenib. A regorafenib nanodrug is fabricated by one-step self-assembly with a clinically often-used fluorescent agent (indocyanine green) for overcoming regorafenib's limitations, towards improving regorafenib's therapeutic efficacy in advanced CRC. This nanodrug (nanoRF) was characterized, and its antitumor effects were assessed in three preclinical CRC models. NanoRF converts regorafenib's delivery approach from oral to intravenous with a significantly high encapsulation efficacy of regorafenib (96%) and a long-time colloidal stability. Nanodrug (nanoRF) markedly prolongs regorafenib's blood circulation by halving clearance rate, and enhances regorafenib's tumor accumulation. Across three preclinical CRC models (xenografted tumor, chemodrug-resistant xenografted tumor, and liver metastasis), nanoRF drastically enhances regorafenib's tumor inhibiting efficacy by 0.5-4 folds and effectively extends survival by 0.5-5 folds. This regorafenib nanodrug is a simple, safe, and efficient therapeutic nanodrug for treating advanced CRC with a ready-to-be-clinically-translated potential.

In vitro and in vivo detection of lactate with nanohybrid-functionalized Pt microelectrode facilitating assessment of tumor development.

Accelerated glucose uptake and "aerobic glycolysis" of tumor cells generates a high-level lactate in extracellular space and within tumor tissue, which is thought to be a hallmark of tumor and closely correlated with tumor development. Here, we report the development of an enzyme-free electrochemical sensing platform based on a Pt-microneedle electrode functionalized with Au nanoparticles (Au-NPs) decorated polydopamine nanospheres (PDA-NSs), and explore its practical application in in vitro and in vivo detection of lactate in different biological samples. Our results demonstrate that in virtue of the nanostructured merits and high electrocatalytic activity, the resultant nanohybrid-microelectrode exhibits good sensitivity and selectivity to the nonenzymatic electrochemical detection of lactate, with a detection limit of 50 µM, a liner range of 0.375-12 mM, and a sensitivity of 11.25 mA mM-1 cm-2, as well as a good anti-interference ability to other active small molecules. The platform quantifies lactate in complex bio-fluids, including cancerous and non-cancerous cell culture media, as well as serum samples, with detecting time 7.5-fold faster than does a clinically-used approach. Moreover, owing to miniaturized size and satisfactory electrochemical performance, the sensor achieves in vivo recording of lactate-related characteristic voltammetric signals within a living tumor, which are positively correlated with tumor burden and growth. Therefore, the platform cannot only be employed for cancer metabolic investigation, but also potentially for clinical assessment of tumor progression, and even clinical diagnosis of other lactate metabolism disorders.

Oxygen-Generating Cyanobacteria Powered by Upconversion-Nanoparticles-Converted Near-Infrared Light for Ischemic Stroke Treatment.

Stroke is one of most common causes of death and disability. Most of neuroprotective agents fail to rescue neurons from cerebral ischemic insults, mainly because of targeting downstream cascading events, such as excitotoxicity, oxidative and nitrosative stress, and inflammation, rather than improving hypoxia that initially occurs. Here, we report a near-infrared light (NIR)-driven nanophotosynthesis biosystem capable of generating oxygen and absorbing carbon dioxide, thus rescuing neurons from ischemia toward treating stroke. Through cerebral delivery of S. elongatus that spontaneously photosynthesize and upconversion nanoparticles (UCNPs), NIR with excellent tissue penetrating capability is converted to visible light by UCNPs to activate S. elongatus generating oxygen in vivo, enhancing angiogenesis, reducing infarction, and facilitating repair of brain tissues, thus improving neuronal function recovery. The combination of cell-biological, biochemical, and animal-level behavioral data provides compelling evidence demonstrating that this oxygen-generating biosystem through jointly utilizing microorganism and nanotechnology represents a novel approach to stroke treatment.

Silk-Based Biomaterials for Cardiac Tissue Engineering.

Cardiovascular diseases are one of the leading causes of death globally. Among various cardiovascular diseases, myocardial infarction is an important one. Compared with conventional treatments, cardiac tissue engineering provides an alternative to repair and regenerate the injured tissue. Among various types of materials used for tissue engineering applications, silk biomaterials have been increasingly utilized due to their biocompatibility, biological functions, and many favorable physical/chemical properties. Silk biomaterials are often used alone or in combination with other materials in the forms of patches or hydrogels, and serve as promising delivery systems for bioactive compounds in tissue engineering repair scenarios. This review focuses primarily on the promising characteristics of silk biomaterials and their recent advances in cardiac tissue engineering.

A Sequentially Responsive Nanosystem Breaches Cascaded Bio-barriers and Suppresses P-Glycoprotein Function for Reversing Cancer Drug Resistance.

Cancer chemotherapy is challenged by multidrug resistance (MDR) mainly attributed to overexpressed transmembrane efflux pump P-glycoprotein (P-gp) in cancer cells. Improving drug delivery efficacy while co-delivering P-gp inhibitors to suppress drug efflux is an often-used nanostrategy for combating MDR, which is however challenged by cascaded bio-barriers en route to cancer cells and P-gp inhibitors' adverse effects. To effectively breach the cascaded bio-barriers while avoiding P-gp inhibitors' adverse effects, a stealthy, sequentially responsive doxorubicin (DOX) delivery nanosystem (RCMSNs) is fabricated, composed of an extracellular-tumor-acidity-responsive polymer shell (PEG-b-PLLDA), pH/redox dual-responsive mesoporous silica nanoparticle-based carriers (MSNs-SS-Py), and cationic ß-cyclodextrin-PEI (CD-PEI) gatekeepers. The PEG-b-PLLDA corona makes RCMSNs stealthy with prolonged blood circulation time. Once tumors are reached, extracellular acidity degrades PEG-b-PLLDA, reversing nanosystem's surface charges to be positive, which drastically improves RCMSNs' tumor accumulation, penetration, and cellular internalization. Within cancer cells, CD-PEI gatekeepers detach to allow DOX unloading in response to intracellular acidity and glutathione and functionally act as a P-gp inhibitor, dampening P-gp's efflux activity by impairing ATP production. Thus, the resultant high-efficacy drug delivery along with reduced P-gp function cooperatively reverses MDR in vitro. Importantly, in preclinical tumor models, DOX@RCMSNs potently suppress MDR tumor growth without eliciting systemic toxicity, demonstrating their potential of clinical translation.

Dual-engineered, "Trojanized" macrophages bio-modally eradicate tumors through biologically and photothermally deconstructing cancer cells in an on-demand, NIR-commanded, self-explosive manner.

To engineer tumor-tropic cells as drug delivery vehicles is a promising strategy to improve therapeutic specificity and efficacy for cancer treatment. However, conventional genetically engineered cell-based drug delivery systems are often capable of initiating single-mode therapy, and lack precise spatiotemporal control over the release of therapeutic payloads at tumor local, thus possibly causing severe systemic toxicity. Here, the macrophages are genetically engineered to encode a non-secreted form of EGFP-TNFα fusion protein and intracellularly carry near-infrared (NIR)-responsive heat-nanogenerators (HIMs). Owing to macrophages' intrinsic tumor tropism and HIMs' photo-responsiveness to NIR, these macrophages (HIMs@eMET) can actively accumulate at tumor sites and undergo controlled photothermolysis induced by NIR-induced HIMs-mediated photothermal effects (PTE). Such heat-induced cell explosion enables spatiotemporally controlled release of non-secreted TNFα from macrophages and effectively kills cancer cells. Importantly, in a preclinical tumor model, HIMs@eMET actively migrate to tumors where PTE and released EGFP-TNFα exhibit an enhanced antitumor effect, suppressing tumor growth and significantly prolonging animal survival without eliciting adverse side effects. Thus, this study demonstrates the potential of such dual-engineered macrophages in bi-modal cancer therapy.

One-step solution synthesis of a two-dimensional semiconducting covalent organometallic nanosheet via the condensation of boronic acid.

In this work, a 2D covalent organometallic nanosheet (COMS) was designed and successfully synthesized through the one-step conjunction of a terpyridine-metal-terpyridine (TMT) sandwich coordinate motif with borate ester covalent heterocyclic (B3O3) linkage via the condensation of boronic acid. The obtained 2D COMS with a cobalt coordination center (2D COMS-Co) showed promising p-type semiconducting properties.

Stepwise synthesis of the heterotrimetallic chains [MRu2(dpa)4X2]0/1+ using group 7 to group 12 transition metal ions and [Ru2(dpa)4Cl].

The CoRu2(dpa)4Cl2 (1) (dpa: 2,2'-dipyridylamide) is synthesized by the reaction of Ru2(OAc)4Cl and Co3(dpa)4Cl2. By mixing 1 with NH3, Co2+ can be removed and result in the formation of unique binuclear complex 4,0-Ru2(dpa)4Cl (2) featuring one coordination pocket supported by free pyridine groups. Hence, this complex can act as an outstanding precursor for the formation of heterotrimetallic chains with MRu2 cores. A series of M-Ru25+ complexes (M = Co2+ (3), Ag+ (4), Mn2+ (5), Fe2+ (6), Zn2+ (7), Cd2+ (8), Pd2+ (9), Rh2+ (10), and Ir2+ (11)) were prepared and isolated, representing the most complete series of heterotrimetallic chains to date. All these metal string complexes are in a linear trimetallic framework helically wrapped by four dpa- ligands, characterized by X-ray diffraction measurements. The bending of the trinuclear metal cores in RhRu2 (10) and IrRu2 (11) (∠Ru-Ru-Rh: 167.58° and ∠Ru-Ru-Ir: 167.61°) indicates that a heterometallic metal-metal bonds (Ru-Rh; Ru-Ir) are generated. The studies from DFT calculation of 10 and 11 coincide with the experimental results. Furthermore, the MRu25+ distances are regulated by the factors including the bonding force of M-pyridyl and the static repulsion between M and Ru25+ unit. Interestingly, the trend for these distances is in line with that observed in trans-M(py)4Cl2 complexes.

Aligned hierarchical Ag/ZnO nano-heterostructure arrays via electrohydrodynamic nanowire template for enhanced gas-sensing properties.

Gas sensing performance can be improved significantly by the increase in both the effective gas exposure area and the surface reactivitiy of ZnO nanorods. Here, we propose aligned hierarchical Ag/ZnO nano-heterostructure arrays (h-Ag/ZnO-NAs) via electrohydrodynamic nanowire template, together with a subsequent hydrothermal synthesis and photoreduction reaction. The h-Ag/ZnO-NAs scatter at top for higher specific surface areas with the air, simultaneously contact at root for the electrical conduction. Besides, the ZnO nanorods are uniformly coated with dispersed Ag nanoparticles, resulting in a tremendous enhancement of the surface reactivity. Compared with pure ZnO, such h-Ag/ZnO-NAs exhibit lower electrical resistance and faster responses. Moreover, they demonstrate enhanced NO2 gas sensing properties. Self-assembly via electrohydrodynamic nanowire template paves a new way for the preparation of high performance gas sensors.

In Situ Electrochemical Sensing and Real-Time Monitoring Live Cells Based on Freestanding Nanohybrid Paper Electrode Assembled from 3D Functionalized Graphene Framework.

In this work, we develop a new type of freestanding nanohybrid paper electrode assembled from 3D ionic liquid (IL) functionalized graphene framework (GF) decorated by gold nanoflowers (AuNFs), and explore its practical application in in situ electrochemical sensing of live breast cell samples by real-time tracking biomarker H2O2 released from cells. The AuNFs modified IL functionalized GF (AuNFs/IL-GF) was synthesized via a facile and efficient dopamine-assisted one-pot self-assembly strategy. The as-obtained nanohybrid assembly exhibits a typical 3D hierarchical porous structure, where the highly active electrocatalyst AuNFs are well dispersed on IL-GF scaffold. And the graft of hydrophilic IL molecules (i.e., 1-butyl-3-methylimidazolium tetrafluoroborate, BMIMBF4) on graphene nanosheets not only avoids their agglomeration and disorder stacking during the self-assembly but also endows the integrated IL-GF monolithic material with unique hydrophilic properties, which enables it to be readily dispersed in aqueous solution and processed into freestanding paperlike material. Because of the unique structural properties and the combinational advantages of different components in the AuNFs/IL-GF composite, the resultant nanohybrid paper electrode exhibits good nonenzymatic electrochemical sensing performance toward H2O2. When used in real-time tracking H2O2 secreted from different breast cells attached to the paper electrode without or with radiotherapy treatment, the proposed electrochemical sensor based on freestanding AuNFs/IL-GF paper electrode can distinguish the normal breast cell HBL-100 from the cancer breast cells MDA-MB-231 and MCF-7 cells, and assess the radiotherapy effects to different breast cancer cells, which opens a new horizon in real-time monitoring cancer cells by electrochemical sensing platform.

Self-Supported Biocarbon-Fiber Electrode Decorated with Molybdenum Carbide Nanoparticles for Highly Active Hydrogen-Evolution Reaction.

Devising and facilely synthesizing an efficient noble metal-free electrocatalyst for the acceleration of the sluggish kinetics in the hydrogen-evolution reaction (HER) is still a big challenge for electrolytic water splitting. Herein, we present a simple one-step approach for constructing self-supported biocarbon-fiber cloth decorated with molybdenum carbide nanoparticles (BCF/Mo2C) electrodes by a direct annealing treatment of the Mo oxyanions loaded cotton T-shirt. The Mo2C nanoparticles not only serve as the catalytic active sites toward the HER but also enhance the hydrophilicity and conductivity of resultant electrodes. As an integrated three-dimensional HER cathode catalyst, the BCF/Mo2C exhibits outstanding electrocatalytic performance with extremely low overpotentials of 88 and 115 mV to drive a current density of 20 mA cm-2 in alkaline and acidic media, respectively. In addition, it can continuously work for 50 h with little decrease in the cathodic current density in both alkaline and acidic solutions. Even better, self-supported tungsten carbide and vanadium carbide based electrodes also can be prepared by a similar synthesis process. This work will illuminate an entirely new avenue for the preparation of various self-supported three-dimensional electrodes made of transition-metal carbides for various applications.

Well-Ordered Oxygen-Deficient CoMoO4 and Fe2O3 Nanoplate Arrays on 3D Graphene Foam: Toward Flexible Asymmetric Supercapacitors with Enhanced Capacitive Properties.

In this work, we report the development of well-ordered hydrogenated CoMoO4 (H-CoMoO4) and hydrogenated Fe2O3 (H-Fe2O3) nanoplate arrays on 3D graphene foam (GF) and explore their practice application as binder-free electrodes in assembling flexible all-solid-state asymmetric supercapacitor (ASC) devices. Our results show that the monolithic 3D porous GF prepared by solution casting method using Ni foam template possesses large surface area, superior electrical conductivity, and sufficient surface functional groups, which not only facilitate in situ growth of CoMoO4 and Fe2O3 nanoplates but also contribute the double-layer capacitance of the resultant supercapacitor. The well-ordered pseudocapacitive metal oxide nanoplate arrays standing up on 3D GF scaffold can provide efficient space and shorten the length for electrolyte diffusion from the outer to the inner region of the electrode material for Faradaic energy storage. Furthermore, one of our major findings is that the introduction of oxygen vacancies in CoMoO4 and Fe2O3 nanoplates by hydrogenation treatment can increase their electronic conductivity as well as improve their donor density and surface properties, which gives rise to a substantially improved electrochemical performance. Benefiting from the synergistic contributions of different components in the nanohybrid electrode, the resultant flexible ASC device with GF/H-CoMoO4 as the positive electrode and GF/H-Fe2O3 as the negative electrode achieves a wide operation voltage of 1.5 V and a maximum volumetric specific capacitance of 3.6 F cm-3, which is two times larger than that of the Ni/GF/CoMoO4//Ni/GF/Fe2O3 device (1.8 F cm-3), and the rate capability is up to 70% as the current density increases from 2 to 200 mA cm-3. Moreover, the Ni/GF/H-CoMoO4//Ni/GF/H-Fe2O3 device also exhibits a high energy density of 1.13 mWh cm-3 and a high power density of 150 mW cm-3, good mechanical flexibility with the decrease in capacitance of less than 4% after being bent inward to different angles and inward to 90° 200 times, and good cycling stability of 93.1% capacitance retention after 5000 cycles.

Solid-State Thin-Film Supercapacitors with Ultrafast Charge/Discharge Based on N-Doped-Carbon-Tubes/Au-Nanoparticles-Doped-MnO2 Nanocomposites.

Although carbonaceous materials possess long cycle stability and high power density, their low-energy density greatly limits their applications. On the contrary, metal oxides are promising pseudocapacitive electrode materials for supercapacitors due to their high-energy density. Nevertheless, poor electrical conductivity of metal oxides constitutes a primary challenge that significantly limits their energy storage capacity. Here, an advanced integrated electrode for high-performance pseudocapacitors has been designed by growing N-doped-carbon-tubes/Au-nanoparticles-doped-MnO2 (NCTs/ANPDM) nanocomposite on carbon fabric. The excellent electrical conductivity and well-ordered tunnels of NCTs together with Au nanoparticles of the electrode cause low internal resistance, good ionic contact, and thus enhance redox reactions for high specific capacitance of pure MnO2 in aqueous electrolyte, even at high scan rates. A prototype solid-state thin-film symmetric supercapacitor (SSC) device based on NCTs/ANPDM exhibits large energy density (51 Wh/kg) and superior cycling performance (93% after 5000 cycles). In addition, the asymmetric supercapacitor (ASC) device assembled from NCTs/ANPDM and Fe2O3 nanorods demonstrates ultrafast charge/discharge (10 V/s), which is among the best reported for solid-state thin-film supercapacitors with both electrodes made of metal oxide electroactive materials. Moreover, its superior charge/discharge behavior is comparable to electrical double layer type supercapacitors. The ASC device also shows superior cycling performance (97% after 5000 cycles). The NCTs/ANPDM nanomaterial demonstrates great potential as a power source for energy storage devices.

Heterobimetallic peroxo-titanium(IV) nitrilotriacetate complexes as single source precursors for preparation of MTiO3 (M = Co, Ni and Zn).

Three isostructural heterobimetallic nitrilotriacetatoperoxotitanate complexes of general formula [M(H(2)O)(5)](2)[Ti(2)(O(2))(2)O(nta)(2)].7H(2)O [M = Co (1), Ni (2) and Zn (3)] have been isolated in pure crystals directly from the quaternary system of M(2+)-Ti(OC(4)H(9))(4)-H(2)O(2)-H(3)nta (H(3)nta = nitrilotriacetic acid) at pH = 4.0 and have been characterized by elemental analyses, IR, thermal analysis (TGA), and single-crystal X-ray diffraction. Single crystal X-ray analysis reveals that the titanium atom in these complexes features seven-fold-coordination, each surrounded by six oxygen atoms and one nitrogen atom. The divalent transition metal ions in these compounds are hexa coordinated, surrounded by five water molecules and one bridged carboxylato oxygen atom. The TGA and XRD results prove that complexes 1-3 undergo facile thermal decomposition to form pure CoTiO(3), NiTiO(3) and ZnTiO(3) at 700 degrees C respectively. The morphologies, microstructures, and crystallinity of the residues obtained after pyrolysis were characterized by transmission electron microscopy and powder X-ray diffraction.