One-Pot Synthesis of Mesoporous Silica Nanocarriers with Tunable Particle Sizes and Pendent Carboxylic Groups for Cisplatin Delivery

Mesoporous silica nanocarriers with tunable particle sizes and different loadings of pendent carboxylic groups were successfully prepared by a straightforward and reproducible strategy, in which carboxyethylsilanetriol sodium salt was co-condensed with tetraethoxyorthosilicate to introduce the carboxylic groups. The key in this strategy was to separate the synthesis process into two steps of the nuclei formation and particle growth. The uniform particle size and ordered structure of the synthesized nanocarriers were manifested by several techniques such as XRD, TEM, SEM, and BET. DLS measurement illustrated that nanocarriers could be well suspended in aqueous solution. The integration and content tunability of the carboxylic groups within mesoporous silica nanoparticles (MSNs) were verified by FT-IR and ²⁹Si NMR. The inherent carboxylic units on the obtained carboxylic group modified MSNs (MSNs-C) effectively enhanced the capture and tailored the release properties of the anticancer drug of cisplatin. The accumulation of drug in the HeLa cells was greatly enhanced due to the highly efficient platinum uptake efficiency transported by the synthesized nanocarriers. The drug encapsulated in the MSNs-C exhibited a higher antitumor activity than free cisplatin against both MCF-7 and HeLa cells

Real-Time Monitoring of Dissolved Oxygen with Inherent Oxygen-Sensitive Centers in Metal–Organic Frameworks

Despite that they are regarded as the ideal sensory platform, there are still no reports on luminescent metal–organic frameworks (LMOFs) for dissolved oxygen (DO) measurement. Here, we reported the rational construction of a platinum­(II) porphyrinic LMOF, PCN-224­(Pt), as an novel porous matrix for the phosphorescent DO sensing with commercially available Pt­(II) meso-tetra­(4-carboxy­phenyl)­porphyrin as the bridging struts, oxygen-sensitive centers, and luminescent reporters. The newly developed probe featured excellent tolerance to harsh chemical environments, excellent photostability as well as pH-independent luminescence, rationalizing its suitability for DO sensing. Thanks to the homogeneous and well-isolated arrangement of the oxygen-accessible sites in the porous network, PCN-224­(Pt) exhibited reversible phosphorescent response and excellent linear Stern–Volmer quenching behavior toward DO. A real-time analysis of DO during the process of enzyme-catalytic reaction exemplified its potentials in industrial and biological applications with oxygen involved

Synthesis of gold Nanoshells through Improved Seed-Mediated Growth Approach: Brust-like, <i>in Situ</i> Seed Formation

Gold nanoshells have shown great potentials in various fields. However, the widely used seed-mediated growth method based on a silica template for gold nanoshells is a complex and time-consuming procedure. In this work, mercaptosilica was first used as a template to synthesize gold nanoshells through improved seed-mediated growth method. It is verified that gold seeds were formed and attached onto the mercaptosilica nanospheres through Brust-like, <i>in situ</i> process, which makes this method extremely time-saving and easy to manipulate. Importantly, the key factors affecting the <i>in situ</i> process were demonstrated, allowing fine control on the synthesis in a highly reproducible manner. The as-synthesized nanoshells are monodisperse with well-defined morphology and tunable near-IR plasmon resonance. Furthermore, other metal nanoparticles such as Pt and Pd could be grafted onto the surface of mercaptosilica nanospheres through the same Brust-like, <i>in situ</i> process. These provide new insights into seed attachment, and the improved seed-mediated growth approach based on Brust-like, <i>in situ</i> seed formation will take an important step forward toward the widespread application of gold nanoshells

Specific Recovery and In Situ Reduction of Precious Metals from Waste To Create MOF Composites with Immobilized Nanoclusters

Incorporation of active metal (especially precious metal) nanocomponents into metal–organic frameworks (MOFs) could capacitate MOFs with enhanced or new properties for innovative industrial applications. Despite increasing numbers of reports of precious metal nanoparticles/MOFs, developing such composites with low cost and high metal loading is still highly desirable. Herein, we demonstrated a novel and facile method to convert precious metal waste to wealth via using thiourea modified MOFs of UiO-66-TU as a proof of principle to recover and immobilize precious metals. The new MOFs exhibited excellent selectivity which allowed for precious metals to be isolated from the waste electronic and electrical equipment (WEEE), which commonly contain different metal species. UiO-66-TU extracts a representative precious metal of Au effectively in a wide pH range, and the maximum Au adsorption capacity could approach 326 mg g^–1. Through a simple reduction treatment, the adsorbed Au ions could be converted to well-dispersed Au nanoclusters (NCs, size below 1.8 nm) embedded in the MOFs, resulting in useful Au NCs/MOF composites. The merits of low cost and considerable Au loading, combined with the good stability of the Zr based MOFs, make the currently prepared Au NCs/UiO-66-TU composites potentially promising for various applications

Surface Modification−Complexation Strategy for Cisplatin Loading in Mesoporous Nanoparticles

High-density carboxyl groups have been successfully grafted onto the pore surface of mesoporous nanocarriers which served to complex with platinum atoms in cisplatin, leading to much increased drug loading efficiency, distinctly prolonged and pH-responsive cisplatin release, and greatly enhanced growth inhibition effect against MCF-7 and HeLa cancer cell lines

Rapid and Specific Aqueous-Phase Detection of Nitroaromatic Explosives with Inherent Porphyrin Recognition Sites in Metal–Organic Frameworks

Development of a rapid and effective method for the detection of 2,4,6-trinitrotoluene (TNT) in aqueous phase has attracted great attention. In this work, the fluorescent porphyrin-based metal–organic frameworks (MOFs) of PCN-224 were successfully exploited as a fluorescent probe for the rapid and selective TNT detection in water media. This strategy combined the advantages of fluorescent porphyrin molecules and porous MOFs, which not only overcame the aggregation of hydrophobic tetrakis­(4-carboxyphenyl)­porphyrin (TCPP) recognition sites but also promoted TNT to interact with recognition sites in virtue of the high surface and intrinsic open structure of MOFs. As a result, a rapid response time of as short as 30 s was obtained for the elaborated fluorescent probe. Meanwhile, the bright red emission of porphyrin units in PCN-224 could be proportionally quenched in correlation with the applied TNT level through the formation of TNT-TCPP complex in the ground state. The specificity of the employed sensory platform for TNT recognition was scarcely affected by other possible coexistent interfering species. Furthermore, this fluorescent PCN-224 probe presented a much higher quenching efficiency for TNT than other structurally similar nitroaromatic compounds and was successfully applied for the quantitative detection of TNT in the mixed nitroaromatic explosive samples. This prefigured their great potentials of practical TNT detection in water media for public safety and security

Effective Adsorption and Enhanced Removal of Organophosphorus Pesticides from Aqueous Solution by Zr-Based MOFs of UiO-67

Though many efforts have been devoted to the adsorptive removal of hazardous materials of organophosphorus pesticides (OPs), it is still highly desirable to develop novel adsorbents with high adsorption capacities. In the current work, the removal of two representative OPs, glyphosate (GP) and glufosinate (GF), was investigated by the exceptionally stable Zr-based MOFs of UiO-67. The abundant Zr–OH groups, resulting from the missing-linker induced terminal hydroxyl groups and the inherent bridging ones in Zr–O clusters of UiO-67 particles, served as natural anchorages for efficient GP and GF capture in relation with their high affinity toward phosphoric groups in OPs. The correlation between the most significant parameters such as contact time, OPs concentration, adsorbent dose, pH, as well as ionic strength with the adsorption capacities was optimized, and the effects of these parameters on the removal efficiency of GP and GF from the polluted aqueous solution were investigated. The adsorption of GP on UiO-67 was faster than that of GF, and a pseudo-second-order rate equation effectively described the uptake kinetics. The Langmuir model exhibited a better fit to adsorption isotherm than the Freundlich model. Thanks to the strong affinity and adequate pore size, the adsorption capacities in UiO-67 approached as high as 3.18 mmol (537 mg) g^–1 for GP and 1.98 mmol (360 mg) g^–1 for GF, which were much higher than those of many other reported adsorbents. The excellent adsorption characteristics of the current adsorbents toward OPs were preserved in a wide pH window and high concentration of the background electrolytes. These prefigured the promising potentials of UiO-67 as novel adsorbent for the efficient removal of OPs from aqueous solution

Synthesis of a Pillar[5]arene-Based Polyrotaxane for Enhancing the Drug Loading Capacity of PCL-Based Supramolecular Amphiphile as an Excellent Drug Delivery Platform

A pillar[5]­arene-based nonionic polyrotaxane (PR) with <i>star</i>-poly­(ε-caprolactone) (<i>S</i>-PCL) as the axle, pillar[5]­arene (DEP5) as the wheel and adamantane as the end-capped group is designed and synthesized. The resulting PR is subsequently assembled with β-cyclodextrin end-capped pH-stimulated poly­(acrylic acid) (CD-PAA) via a host–guest interaction to form the supramolecular pseudoblock polymer PR-PAA. This supramolecular pseudoblock polymer could self-assemble in aqueous solution to produce PR-PAA-based supramolecular vesicular nanoparticles (PR-SVNPs), which present significantly enhanced drug loading capacity (DLC, 45.6%) of DOX, much higher than those of superamphiphiles (PCL-PAA, 17.1%). Such a high DLC of PR-SVNPs can be most probably attributed to the greatly decreased crystallinity of PCL in PR. Moreover, the loaded drugs could be selectively released in an acidic microenvironment-responsive manner. Compared to free DOX, the DOX-loaded PR-SVNPs (DOX@PR-SVNPs) shows much enhanced cellular uptake and cytotoxicity against the SMMC-7721. More importantly, thanks to the enhanced permeability and retention (EPR) effect, DOX@PR-SVNPs exhibits appealing features such as extremely low toxicity, highly efficient intratumoral accumulation and substantial antitumor efficacy in vivo