Mingyi Guo

pH-Triggered Controlled Drug Release from Mesoporous Silica Nanoparticles via Intracelluar Dissolution of ZnO Nanolids

Acid-decomposable, luminescent ZnO quantum dots (QDs) have been employed to seal the nanopores of mesoporous silica nanoparticles (MSNs) in order to inhibit premature drug (doxorubicin) release. After internalization into HeLa cells, the ZnO QD lids are rapidly dissolved in the acidic intracellular compartments, and as a result, the loaded drug is released into the cytosol from the MSNs. The ZnO QDs behave as a dual-purpose entity that not only acts as a lid but also has a synergistic antitumor effect on cancer cells. We anticipate that these nanoparticles may prove to be a significant step toward the development of a pH-sensitive drug delivery system that minimizes drug toxicity.

Synthesis of a porous aromatic framework for adsorbing organic pollutants application

Porous organic frameworks (POFs) have attracted considerable attention due to their high surface areas and good mechanical properties. A series of vivid characteristics in POFs, such as their plentiful phenyl rings texture, their high surface area, uniform pore size distribution and permanent porosity, make themselves suitable adsorbents to adsorb organic pollutants. To synthesize a new porous aromatic framework being composed of only phenyl rings, a monomer 1,3,5-tris(4-bromophenyl)benzene was employed. PAF-5 has been synthesized successfully using the Yamamoto-type Ullmann reaction. This material was characterized by Fourier transform infrared spectroscopy (FT-IR), 13C solid-state NMR, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and N2 gas sorption. PAF-5 displaying high stability and high surface area exhibits excellent abilities to adsorb organic chemical pollutants at saturated vapour pressure and room temperature.

Acid degradable ZnO quantum dots as a platform for targeted delivery of an anticancer drug

Efficacious chemotherapy mainly hinges on the tumor-specific delivery of anticancer drugs. Herein we report a successful fabrication of highly photoluminescent and water dispersible ZnO quantum dotsvia a new ligand exchange free strategy. In addition to bioimaging, ZnO QDs have also been evaluated as a platform for targeted and pH responsive intracellular delivery of an anticancer drug. The cancer targeting feature is endowed by conjugating folic acid on to the surface of ZnO–NH2 QDs via an amidation reaction. Doxorubicin (DOX) is then successfully loaded onto the folic acid functionalized ZnO QDs by capitalizing on its marked tendency towards the formation of metal complexes. Drug loaded ZnO-FA QDs remain stable at physiological pH but readily disintegrate in the mildly acidic intracellular environment of cancer cells as validated by a drug release profile, confocal microscopy and a cell-cytotoxicity assay. Compared to the conventional drug nanovector, ZnO-FA QDs themselves manifest a significant therapeutic activity after reaching their targeted site, therefore, combined DOX and ZnO QDs can be more efficacious than either alone. Hence, this approach provides a valuable ZnO QDs-based nanovector that can simultaneously realize targeting, diagnosis, and therapy of cancer cells.

Novel mesoporous silica spheres with ultra-large pore sizes and their application in protein separation

A series of novel mesoporous silica materials with ultra-large pores (20 to 40 nm in size), interconnected channel structure, thick walls (15 to 20 nm), high hydrothermal stability and selective protein adsorption were synthesized via a new synthetic strategy. We used Brij-56 and Brij-97 as templates and ethyl acetate (EA) and dimethyl o-phthalate (DOP) as additives in a neutral pH system to afford three novel spherical mesoporous silica materials (denoted as B56-E-20, B56-D-33 and B97-D-40) having controllable, interconnected mesoscale channels with diameters of 20, 33 and 40 nm, respectively. The products have shown effective performance in size-selective adsorption of biomacromolecules, demonstrating great potentials in biomacromolecular separation. The molecular weight ranges of the proteins selectively adsorbed in B56-E-20, B56-D-33 and B97-D-40 are 50–55, 60–65 and 70–100 KDa, respectively. Moreover, the products show good hydrothermal stability and can maintain the mesostructure in boiling water over 5 days. This work has bridged the gap in the synthesis of ultra-large pore between mesoporous and macroporous biomaterials and their application in biomacromolecular separation.

Targeted Synthesis of Porous Aromatic Frameworks and their Composites for Versatile, Facile, Efficacious, and Durable Antibacterial Polymer Coatings

Novel quaternary pyridinium-type porous aromatic frameworks, PAF-50, and their composites, AgCl-PAF-50, have been synthesized to effectively and efficiently inhibit the growth of bacteria. Most importantly, both PAF-50 and AgCl-PAF-50 have excellent compatibility with conventional polymers, which lead to great operation flexibility and versatility for antibactrial coatings on various medical devices simply via solution or spray coating.

Facile fabrication of metal–organic framework films promoted by colloidal seeds on various substrates

With the aid of In(OH)(BDC) colloidal seeds, metal–organic framework films (In(OH)(BDC)) have been fabricated by a simple solvothermal reaction of 1,4-benzenedicarboxylic acid (H2BDC) and In(NO3)3·xH2O in DMF on various substrates with different surface conditions.

pH dictates the release of hydrophobic drug cocktail from mesoporous nanoarchitecture.

Combination therapy has been a norm in clinical practice to effectively treat cancer. Besides polytherapy, nowadays, smart and nanobased drug carriers are extensively being explored to deliver drugs according to pathophysiological environment of diseases. In this regard, herein we designed intelligent mesoporous architecture, incorporating both combinational therapy with smart nanotechnology, to simultaneously deliver two highly hydrophobic chemotherapeutic drugs in response to extracellular and/or intracellular acidic environ of tumor. Novelty of the system lies in the employment of acid responsive ZnO QDs to clog not only the nanochannels of mesoporous silica, encapsulating one hydrophobic drug, but also exploitation of chelate forming propensity of another hydrophobic drug (curcumin) to load a significant quantity onto the surface of ZnO nanolids. Cell viability results revealed an extraordinarily high cytotoxic efficiency of that lethal drug cocktail even at a concentration as low as 3 μg/mL nanocarrier. We envision that this sophisticated nanocarrier, which utilizes both interior pore and exterior surface of nanolids for loading different hydrophobic guest molecules and their subsequent acid responsive release, will undoubtedly, illustrates its remarkable potential in targeted chemotherapy.

Lethal drug combination: arsenic loaded multiple drug mesoporous silica for theranostic applications.

Simultaneous delivery of multiple therapeutic agents is of great importance for effective chemotherapy due of its well-known drug synergism and suppression to chemoresistance. We report a new theranostic nanoformulation to shuttle multiple chemotherapeutic agents for successfully exterminating cancer cells. This strategy is based on the fabrication of magnetite doped mesoporous silica nanoparticles (MSNs) in which both internal porous and external surface of MSN are respectively exploited to load two different kinds of cytotoxic cargoes. Notably, an exceptionally high quantity (29%) of poorly hydrophobic drug camptothecin (CPT) is loaded into the nanopores of MSNs; however, in previous reports less than 1% loading efficiency is reported. Following CPT loading in the pores of MSNs, another unconventional but FDA approved arsenic trioxide (ATO) is conjugated onto the surface of nanocomposite via exploiting the thiophilic nature of ATO. Cell inhibition performance of dual drug nanoformulation is significantly higher than single drug formulation, possibly due to additional or synergistic effect, as low as 3 μg/ml of double drug nanocarrier were found effective to exterminate cancer cells. Besides drug delivery, the presence of superparamagnetic magnetite nanocrystals additionally empowers this system to be used as a contrast agent in magnetic resonance (MR) imaging for either monitoring diseased tissues or feedback of chemotherapy. We anticipate that the integration of combination therapy with nanotechnology coupled with versatile magnetic manipulation feature may prove a significant step forward toward the development of effective theranostic agents.

Magnesium hydroxide nanoplates: a pH-responsive platform for hydrophobic anticancer drug delivery

The cost of conventional chemotherapeutic drugs is substantially high, and biomedical researchers are constantly hunting for cheap and effective chemotherapeutic alternatives. Recently, curcumin has emerged as a cost effective anticancer remedy, however, the low bioavailability of curcumin has been a major impediment to its successful utilization for disease management. In this work, we developed a highly biocompatible magnesium hydroxide as an intelligent nanocarrier for delivering curcumin into cancer cells. Curcumin was loaded onto magnesium hydroxide nanoplates via a complexation strategy. Furthermore, these drug conjugated nanoparticles not only achieve efficient loading of a highly hydrophobic drug, but also exhibit pH responsive release in extracellular or intracellular acid environments, validated by in vitro drug release, confocal microscopy and MTT assay. These biocompatible nanoplates can be promising candidates for the further development of smart drug delivery nanodevices.

Design of zeolite frameworks with cross-linked channels through constrained assembly of atoms

Abstract A computational method for design of zeolite frameworks has been developed through constrained assembly of atoms around a predefined channel structure. The forbidden zones, corresponding to a porous pattern, are first defined in a unit cell and then atoms are placed outside of the forbidden zones based on specified symmetry and distance constraints. Employing this method, a number of known zeolite frameworks, as well as new hypothetical frameworks, especially with cross-linked channels, can be generated.