Stimuli-Responsive Polymer-Based Nanosystems for Cancer Theranostics

Stimuli-responsive polymers can respond to internal stimuli, such as reactive oxygen species (ROS), glutathione (GSH), and pH, biological stimuli, such as enzymes, and external stimuli, such as lasers and ultrasound, etc., by changing their hydrophobicity/hydrophilicity, degradability, ionizability, etc., and thus have been widely used in biomedical applications. Due to the characteristics of the tumor microenvironment (TME), stimuli-responsive polymers that cater specifically to the TME have been extensively used to prepare smart nanovehicles for the targeted delivery of therapeutic and diagnostic agents to tumor tissues. Compared to conventional drug delivery nanosystems, TME-responsive nanosystems have many advantages, such as high sensitivity, broad applicability among different tumors, functional versatility, and improved biosafety. In recent years, a great deal of research has been devoted to engineering efficient stimuli-responsive polymeric nanosystems, and significant improvement has been made to both cancer diagnosis and therapy. In this review, we summarize some recent research advances involving the use of stimuli-responsive polymer nanocarriers in drug delivery, tumor imaging, therapy, and theranostics. Various chemical stimuli will be described in the context of stimuli-responsive nanosystems. Accordingly, the functional chemical groups responsible for the responsiveness and the strategies to incorporate these groups into the polymer will be discussed in detail. With the research on this topic expending at a fast pace, some innovative concepts, such as sequential and cascade drug release, NIR-II imaging, and multifunctional formulations, have emerged as popular strategies for enhanced performance, which will also be included here with up-to-date illustrations. We hope that this review will offer valuable insights for the selection and optimization of stimuli-responsive polymers to help accelerate their future applications in cancer diagnosis and treatment.

Microbiota and plant-derived vesicles that serve as therapeutic agents and delivery carriers to regulate metabolic syndrome

The gut is a fundamental organ in controlling human health. Recently, researches showed that substances in the intestine can alter the course of many diseases through the intestinal epithelium, especially intestinal flora and exogenously ingested plant vesicles that can be transported over long distances to various organs. This article reviews the current knowledge on extracellular vesicles in modulating gut homeostasis, inflammatory response and numerous metabolic disease that share obesity as a co-morbidity. These complex systemic diseases that are difficult to cure, but can be managed by some bacterial and plant vesicles. Vesicles, due to their digestive stability and modifiable properties, have emerged as novel and targeted drug delivery vehicles for effective treatment of metabolic diseases.

Stable Discoidal Bicelles: Formulation, Characterization, and Functions

Bicellar mixtures have been used as alignable membrane substrates under a magnetic field applicable for the structural characterization of membrane-associated proteins. Recently, it has shown that bicelles can serve as nanocarriers to effectively deliver hydrophobic therapeutic molecules to cancer cells with a three- to ten-fold enhancement compared to that of liposomes of a chemically identical composition. In this chapter, detailed preparation protocol, common structural characterization methods, the structural stability, the cellular uptake and a few unique functions of bicellar nanodiscs are discussed.

Synthesis of Gum Arabic-g-polyaniline using diode laser

Grafting of polyaniline (PANI) on Gum Arabic (GA) was carried out in the presence of ceric ammonium nitrate (CAN) under acidic conditions by diode laser as initiator. The grafting condition was optimized by varying the diode laser power, exposure time, concentrations of PANI, CAN, GA, reaction time and temperature were carefully optimized to achieve the highest percentage of grafting yield % GY (90%) and percentage of graft efficiency % GE (36%). The Fourier-transform infrared spectroscopy (FTIR), ¹H NMR, X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), and Scanning electron micrographs (SEM) techniques have been used for the characterization of the produced graft copolymer GA-g-PANI, which used as drug delivery carrier to control cancer in brain. This study focused to new trends and latest developments in this area where diode laser was found to be efficient and, clean method for synthesis GA-g-PANI.

One-Step Synthesis of Nitrogen-Doped Hydrophilic Mesoporous Carbons from Chitosan-Based Triconstituent System for Drug Release

In situ nitrogen-doped hydrophilic mesoporous carbon spheres with different carbon-to-silicon (C/Si) ratios (NMCs-x/3, x = 5, 6, 7, and 8) were prepared by one-step method coupled with a spray drying and carbonizing technique, in which triblock copolymer (F127) and tetraethyl orthosilicate (TEOS) were used as template agents, and biocompatible chitosan (CS) was used as the carbon source and nitrogen source. These carbon materials were characterized by TG, BET, XRD, Raman, FTIR, TEM, XPS, and contact angle measuring device. The adsorption and release properties of mesoporous carbon materials for the poorly soluble antitumor drug hydroxycamptothecin (HCPT) were investigated. Results showed that nanospherical mesoporous carbon materials were successfully prepared with high specific surface area (2061.6 m²/g), narrowly pore size distribution (2.01-3.65 nm), and high nitrogen content (4.75-6.04%). Those NMCs-x showed a satisfactory hydrophilicity, which gradually increased with the increasing of surface N content. And the better hydrophilicity of NMCs-x was, the larger adsorption capacity for HCPT. The absorption capacity of NMCs-x towards HCPT was in the following orders: q_NMCs-5/3 > q_NMCs-6/3 > q_NMCs-7/3 > q_NMCs-8/3. NMCs-5/3 had the largest saturated adsorption capacity of HCPT (1013.51 mg g^-1) and higher dissolution rate (93.75%).

Stable Discoidal Bicelles: A Platform of Lipid Nanocarriers for Cellular Delivery

Bicellar mixtures have been used as alignable membrane substrates for the structural characterization of membrane-associated proteins. Most recently, it has been shown that bicelles can serve as nanocarriers to effectively deliver hydrophobic molecules to cancer cells with a 3- to 10-fold enhancement compared to that of chemically identical liposomes. In this chapter, a detailed preparation protocol, common structural characterization methods, the structural stability and the cellular uptake of bicellar nanodisks are discussed.

Improved angiogenesis and healing in crush syndrome by fibroblast growth factor-2-containing low-molecular-weight heparin (Fragmin)/protamine nanoparticles

BACKGROUND

We produced fibroblast growth factor (FGF)-2-containing low-molecular-weight heparin (Fragmin)/protamine nanoparticles (FGF-2 + F/P NPs). The purpose of this study was to evaluate the effectiveness of the local administration of FGF-2 + F/P NPs on repairing crush syndrome (CS)-injured lesions after compression release using a nonlethal and reproducible CS injury rat model.

MATERIALS AND METHODS

The hind limbs of the anesthetized rats were compressed for 6 h using 3.6 kg blocks, as previously described. The effects of administering FGF-2 + F/P NPs (group A), F/P NPs alone (group B), FGF-2 alone (group C), and saline (control; group D) were examined. Motor function, surface blood flow in the hind limbs, and the wet/dry weight ratio in the tibialis anterior muscle were examined for 1-28 d after the compression release. Histologic analyses were also performed.

RESULTS

At the middle and late stages (3-28 d after the compression release), group A had higher scores in the motor function, improved blood flow, increased number of blood vessels, and faster recovered muscle tissue, compared with the other groups. There was no significant difference in enhanced edema in the tibialis anterior muscle among all groups.

CONCLUSIONS

The local administration of FGF-2 + F/P NPs to a CS-injured lesion was effective in repairing damaged muscle tissue after compression release.