Liru Cui

An Enzyme-Responsive Controlled Release System of Mesoporous Silica Coated with Konjac Oligosaccharide

A simple and green method to fabricate an ingenious enzyme-responsive drug controlled release system was presented. Mesoporous silica material (mSiO2) 100 nm in size was used as the host, and Konjac oligosaccharide (KOGC) was employed to seal the nanopores of mSiO2 to inhibit the drug release. Rhodamine B was used as the model cargo to reveal the release behavior of the system. The KOGC-modified mSiO2 (mSiO2@KOGC) retains the drug until it reaches the colonic environment where bacteria secrete enzymes (β-mannanase) can degrade KOGC and make drug release. The amount of KOGC and enzyme can be used to adjust the release performance. And all the release behaviors fit the two-step Higuchi model, which predominate by KOGC degradation and mesoporous structure, respectively. With well bioactivity and selectivity, the system has potential application as an oral medicine carrier for treating intestinal disease.

pH-responsive controlled-release system based on mesoporous bioglass materials capped with mineralized hydroxyapatite

A controlled release system with pH-responsive ability has been presented. Mesoporous bioglass (MBG) was used as the drug carrier and a spontaneous mineralization method was adopted to cap the pores of the carrier with hydroxyapatite (HAp) and to restrict the drug release. It is a simple and green method to realize the ingenious pH-sensitive controlled release. The model drug, metformin hydrochloride (MH), was loaded simultaneously with the mineralization process. Due to the degradation of HAp at acid environments, the system shows well pH-sensitive drug release ability. The release kinetics can be easily adjusted by the mineralization time and the ion concentration of media. The system is recommended as a promising candidate as a pH-sensitive vehicle for drug controlled release to low pH tissues, such as inflammatory sites and tumors.

Fe3O4@mSiO2 core–shell nanocomposite capped with disulfide gatekeepers for enzyme-sensitive controlled release of anti-cancer drugs

Multifunctional nanocarriers based on the magnetic Fe3O4 nanoparticle core and bis-(3-carboxy-4-hydroxy phenyl) disulfide (R-S-S-R1) modified mesoporous silica shell (Fe3O4@mSiO2@R-S-S-R1) were synthesized for cancer treatment through passive targeting and enzyme-sensitive drug release. Anti-cancer drug doxorubicin (DOX) was used as the model cargo to reveal the release behavior of the system. The drug loading system (DOX-Fe3O4@mSiO2@R-S-S-R1) retains the drug until it reaches the tumor tissue where glutathione reductase (GSH) can degrade the disulfide bonds and release the drug. Furthermore, the grafting amount of R-S-S-R1 can be used to adjust the release performance. All the release behaviors fit the Higuchi model very well and the release kinetics are predominated by disulfide bond degradation and mesoporous structure. With good bioactivity and targeted release performance, the system could play an important role in the development of intracellular delivery nanodevices for cancer therapy.

NIR-sensitive UCNP@mSiO2 nanovehicles for on-demand drug release and photodynamic therapy

Nanocomposites have attracted the most attention for antitumor treatment. Here, we present a near-infrared (NIR) sensitive nanovehicle to reveal synergistic chemotherapy and photodynamic therapy (PDT). Upconverting nanoparticles (UCNP) NaYF4:Yb, Tm@NaYF4 were adopted as the core using a one-step coprecipitation method to realize the coating of the mesoporous silica shell and the doping of photosensitizer Hypocrellin A (HA). Furthermore, a UV light-cleavable 4-(2-carboxy-ethylsulfanylmethyl)-3-nitro-benzoic acid linker (CNBA) was synthesized and grafted outside as a “gate” to insure the encapsulation of the anticancer drug doxorubicin (DOX). Upon NIR irradiation, the UV light emission (derived from UCNP) can induce the break of the CNBA linker to make the “gate” open and cause drug release. Besides, the blue emission (450–470 nm) can excite HA to generate reactive oxygen (ROS) to achieve PDT. Owing to the nanoscale particle size (75 nm) and targeting transferrin (Tf) modification, these nanocomposites possess fast uptake by cancer cells (HeLa and MCF-7) and the enhanced cytotoxicity is derived from the synergistic effect of chemotherapy and PDT that would easily be controlled by the acting strength and time of NIR irradiation. Hence, the NIR light-sensitive nanocomposites are expected to be the promising and flexible platform for cancer treatment.

A novel pH-responsive controlled release system based on mesoporous silica coated with hydroxyapatite

With well bioactive and nontoxic, hydroxyapatite (HAp) was employed to seal the nanopores of mesoporous silica (MCM-41) to realize the pH-responsive controlled release. First, MCM-41 was modified with cationic polymer, poly-(diallyldimethylammoniumchloride) (PA). And after the addition of Ca2+/PO43−, HAp precipitation can take place based on the cationic sites derived from PA. It is a simple and effective way to obtain HAp coating MCM-41 system (MHAs). The structure of the system was characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, N2 adsorption–desorption and so on. Metformin hydrochloride was used as the model drug, and the drug release performance and the release kinetics of the system were investigated in detail. Because of the degradation of HAp under acid condition, the drug loading MHAs showed a well pH-sensitive controlled release behavior. From above investigation, MHAs is a promising platform to construct a pH-responsive controlled drug delivery system, especially for some low pH tissues, such as inflammatory and tumor.

Enzyme-sensitive magnetic core–shell nanocomposites for triggered drug release

Fe3O4@mSiO2 (magnetic Fe3O4 core coated by a mesoporous silica shell) nanoparticles were successfully synthesized as a carrier. The anti-cancer drug doxorubicin (DOX) and chlorambucil (Chl) were used as the model cargo. After the drug-loading, a sodium hyaluronic acid (HA) cross-linked gel was adopted to coat the outside of the Fe3O4@mSiO2 nanoparticles as a layer (named as drug–Fe3O4@mSiO2–HA) to prevent drug pervasion. The detailed release kinetics were investigated, revealing the sensitive release triggered by hyaluronidase (HAase), a major enzyme which is rich in the tumor microenvironment, which can degrade the HA shell to induce the enzyme sensitive drug release. Moreover, there are some HA receptors in many tumor areas, associating with magnetic targets to further ensure the specific targeted drug delivery. With these improved performances, these smart multifunctional nanocomposites are expected to possess potential applications in the biopharmaceutical for cancer therapy.

Simple way to obtain pH-sensitive drug release from functional mesoporous silica materials.

A novel pH-sensitive drug release system has been synthesised by functional mesoporous silica materials. SBA-15, calcium modified SBA-15 (Ca-SBA-15) and phosphate modified SBA-15 (PO4-SBA-15) were synthesised using solvent evaporation method. It is a simple and feasible way to prepare the doping mesoporous silica materials. They show the large surface are, high pore volume and uniform pore size. Metformin hydrochloride was used as the model drug, and the control release behaviour was investigated. The functional mesoporous silica materials show the pH sensitive drug release behaviour because of the adjustable interaction between the drug molecule and the host.