Design of Metal-Organic Frameworks for pH-Responsive Drug Delivery Application

Metal-Organic Frameworks (MOFs) have aroused great interest in the field of nanoscience and nanotechnology particularly in biomedical domains, such as Drug Delivery System (DDS), Biomedical Imaging (BI) and Photodynamic Therapy (PDT). As an emerging material, MOFs possess extraordinarily high surface area, controllable particle size and good biocompatibility. With extraordinary flexibility in the selection of organic and inorganic components, MOFs can rationally be tuned to obtain the materials having versatile structures and porosities. MOFs can serve as ideal vehicles for DDS, BI and PDT through modification and function. In this review, we summarized the design and synthetic strategies for preparing MOFs and introduced their recent advanced usage in DDS, BI and PDT. Finally, the prospect and future challenges of these nanomaterials are also documented.

Synthesis of High-Quality Carboxyl End-Functionalized Poly(3-hexylthiophene)/CdSe Nanocomposites

Carboxyl end-functionalized poly(3-hexylthiophene) (P3HT-COOH) was grafted chemically with CdSe nanocrystals (NCs) by a phosphine-free method. The particle quality of P3HT-COOH/CdSe nanocomposites was better than that of P3HT/CdSe nanocomposites, which were synthesized using the same method. Nanocrystals with controllable particle size exhibited a wurtzite crystalline structure and showed excellent nanocrystal dispersion in the P3HT-COOH matrix. Photoluminescence (PL) characterization performed on nanocomposites suggested the efficient charge transfer at the P3HT-COOH/CdSe interface. This approach based on the phosphine-free method is not only environmentally friendly but also highly efficient.

Antagonistic Effect of Azoxystrobin Poly (Lactic Acid) Microspheres with Controllable Particle Size on Colletotrichum higginsianum Sacc

Size-controlled azoxystrobin-poly (lactic acid) microspheres (MS) were prepared by an oil/water emulsion solvent evaporation approach. The hydrated mean particle sizes of the MS1, MS2, and MS3 aqueous dispersions were 130.9 nm, 353.4 nm, and 3078.0 nm, respectively. The drug loading and encapsulation efficiency of the azoxystrobin microspheres had a positive relationship with particle size. However, the release rate and percentage of cumulative release were inversely related to particle size. The smaller-sized microspheres had a greater potential to access the target mitochondria. As a result, the more severe oxidative damage of Colletotrichum higginsianum Sacc and higher antagonistic activity were induced by the smaller particle size of azoxystrobin microspheres. The 50% lethal concentrations against Colletotrichum higginsianum Sacc of MS1, MS2, and MS3 were 2.0386 μg/mL, 12.7246 μg/mL, and 21.2905 μg/mL, respectively. These findings reveal that particle size is a critical factor in increasing the bioavailability of insoluble fungicide.

Porous metal–organic frameworks based on 3,6-bis(4-benzoic acid)-N-(4-benzoic acid)carbazole for HPLC separation of small organic molecules

A stable porous MOF with a controllable particle size can be used as an HPLC situational phase for small organic molecule separations.

Deposition of Controllable Nanoparticles by Hybrid Aerodynamic and Electrostatic Spray

Generating uniform and size controllable nanoparticles are important for various analytical and industrial applications. Here, we propose the hybrid aerodynamic and electrostatic spray system with a large amount of size-controlled nanoparticles. The aerodynamic force easily produces a large amount of sprayed droplets and the electric field assists in secondary breakup of sprayed droplets. The charge of droplets was evaluated to understand the mechanism of controllable particle size because the size and uniformity of particles are determined by the distributions of droplets after evaporation. The distributions of particles are evaluated with a scanning mobility particle sizer (SMPS) technique and a field emission scanning electron microscope (FE-SEM) images. The size and aggregation of the particles are reduced and controlled by electric field strengths.