Chitosan and its derivatives as vehicles for drug delivery

An overview of biodegradable nanomaterials and applications in vaccines

Vaccination is the most cost-effective and sustainable way to prevent and eliminate infectious diseases. Compared with traditional vaccines, novel vaccines have better stability, longer duration and require less antigen usage. In addition, novel vaccines have better immune effects and significantly less toxic side effects. However, both novel vaccines and traditional vaccines require carrier molecules or adjuvants to produce an optimal immune response. There is an increasing demand for vaccine adjuvants and delivery systems that can induce stronger immune response whilst reducing production cost and the dose of vaccine. In recent years, nanotechnology has played an important role in the development of novel vaccine adjuvants and nano-delivery systems. Biodegradable materials have also received a lot of attention in medical science because they have excellent biocompatibility, biodegradability and low toxicity, which can protect antigens from degradation, increase antigen stability and provide slow release; resulting in enhanced immunogenicity. Therefore, biodegradable nanoparticles have attracted much attention in the formulation of vaccines. In this review, we outline some key features of biodegradable nanomaterials in the developing safer and more effective vaccines. The properties, structural characteristics, advantages and disadvantage of the biodegradable nanomaterials will be systematically reviewed. Additionally, applications, research progress and future prospects of biodegradable nanomaterials are discussed. This review will be help in future research work directed at developing biodegradable vaccine adjuvants or delivery carriers.

Patented therapeutic approaches targeting LRP/LR for cancer treatment

Introduction: The ubiquitously expressed 37 kDa/67 kDa high-affinity laminin receptor (laminin receptor precursor/laminin receptor, LRP/LR) is a protein found to play several roles within cells. The receptor is located in the nucleus, cytosol and the cell surface. LRP/LR mediates cell proliferation, cell adhesion and cell differentiation. As a result, it is seen to enhance tumor angiogenesis as well as invasion and adhesion, key steps in the metastatic cascade of cancer. Recent findings have shown that LRP/LR is involved in the maintenance of cell viability through apoptotic evasion, allowing for tumor progression. Thus, several patented therapeutic approaches targeting the receptor for the prevention and treatment of cancer have emerged.Areas covered: The several roles that LRP/LR plays in cancer progression as well as an overview of the current therapeutic patented strategies targeting LRP/LR and cancer to date.Expert opinion: Small molecule inhibitors, monoclonal antibodies and small interfering RNAs might act used as powerful tools in preventing tumor angiogenesis and metastasis through the induction of apoptosis and telomere erosion in several cancers. This review offers an overview of the roles played by LRP/LR in cancer progression, while providing novel patented approaches targeting the receptor as potential therapeutic routes for the treatment of cancer as well as various other diseases.

Preparation and application of dextran and its derivatives as carriers

As a natural and renewable biological macromolecule, dextran not only has excellent biodegradability, but also has good biocompatibility. Dextran and its derivatives are functional polymers for the construction of targeted drug delivery systems. Herein, the application of dextran as prodrug and nanoparticle/nanogel/microsphere/micelle carrier for targeting drug delivery system was summarized. It is clarified that dextran is an important biomaterial with application value.

Sugar ligand-mediated drug delivery

Sugar ligand molecules, such as mannose, galactose and glucose, can bind to drug-delivery systems, making them targeted. These glycosylation ligands have the advantages of nontoxicity, no immunogenicity, good biocompatibility and biodegradation. They can be widely used in glycosylation-modified drug-delivery systems. Herein, the targeting mechanisms, synthesis methods and targeting characteristics of glycosylation-modified drug-delivery systems were reviewed.

Nanoparticles for ocular drug delivery: modified and non-modified chitosan as a promising biocompatible carrier

The eye is a very important, yet sensitive organ, presenting complex anatomy. To overcome its protective mechanisms, with the aim of improving drug delivery, drug encapsulation in nanocarriers is considered in this review. Chitosan is found to be an excellent drug carrier and its application in ophthalmology is being extensively researched. This mucoadhesive biopolymer can protect the encapsulated molecule, optimize its mode of action and minimize any existent risk. Moreover, chitosan and its derivatives may provide advantageous properties to the system such as thermoresponsivity and pH dependency. Finally, dual systems of chitosan with other carriers, such as poly (lactic-co-glycolic acid) and alginate, are also mentioned in this review, as they may offer additional benefits such as higher permeation due to different interaction of each carrier with the corneal layers.

The dextrans as vehicles for gene and drug delivery

Dextran has become a hot research topic in drug vehicle material because of its biodegradable, nonspecific cell adhesion, resistance to protein adsorption, low price and ease of structural modification. The fate and changes of dextran in vivo are not fully understood. It is helpful to guide the design and modification of dextran drug vehicles to clarify the changes in the morphology, metabolism and function of drug targets. With the deep understanding of dextran and the emergence of new functional dextran derivatives, its application in nanodrug delivery systems will be more and more, clinically applicable delivery systems may also be available.

Identification and imaging of miR-155 in the early screening of lung cancer by targeted delivery of octreotide-conjugated chitosan-molecular beacon nanoparticles

Lung cancer is still the most common cancer globally. Early screening remains the key to improve the prognosis of patients. There is currently a lack of specific and sensitive methods for early screening of lung cancer. In recent years, studies have found that microRNA plays an important role in the occurrence and development of lung cancer and become a biological target in the early diagnosis of lung cancer. In this study, lung cancer cells, subcutaneous xenografts of lung cancer in nude mice, and Lox-Stop-lox K-ras G12D transgenic mice were used as models. The transgenic mice displayed the dynamic processes from normal lung tissue to atypical hyperplasia, adenomas, carcinoma in situ and lung adenocarcinoma. It was found that miR-155 and somatostatin receptor 2 (SSTR2) were expressed in all the disease stages of transgenic mice. Through molecular beacon (MB) technology and nanotechnology, chitosan-molecular beacon (CS-MB) nanoparticles and targeted octreotide (OCT) were conjugated and synthesized. The octreotide-conjugated chitosan-molecular beacon nanoparticles (CS-MB-OCT) can specifically bind to SSTR2 expressed by the lung cancer cells to achieve the goal of identification of lung cancer cells and imaging miR-155 in vivo and in vitro. Fluorescence imaging at different disease stages of lung cancer in Lox-Stop-lox K-ras G12D transgenic mice was performed, and could dynamically monitor the occurrence and development of lung cancer by different fluorescence intensity ranges. The current research, in turn, provides new idea, new method, and new technology for the early screening of lung cancer.

Chitosan-Modified PLGA Nanoparticles for Control-Released Drug Delivery

Poly (lactic-co-glycolic acid) nanoparticles (PLGA NPs) are well recognized as an ideal drug delivery carrier for their biocompatibility and biodegradability. In order to overcome the disadvantage of drug burst release, chitosan (CS) was used to modify the PLGA nanoparticles. In this work, CS-PLGA nanoparticles with different ratio of CS to PLGA were prepared using high-gravity rotating packed bed (RPB). With the increase of amount of CS, the particle size increased from 132.8 ± 1.5 nm to 172.7 ± 3.2 nm, zeta potential increased from -20.8 ± 1.1 mV to 25.6 ± 0.6 mV, and drug encapsulation efficiency increased from 65.8% to 87.1%. The initial burst release of PLGA NPs reduced after being modified by CS, and the cumulative release was 66.9%, 41.9%, 23.8%, and 14.3%, after 2 h, respectively. The drug release of CS-modified PLGA NPs was faster at pH5.5 than that at pH 7.4. The cellular uptake of CS-modified PLGA NPs increased compared with PLGA NPs, while cell viability was reduced. In conclusion, these results indicated that CS-modified, PTX-loaded PLGA NPs have the advantages of sustained drug release and enhanced drug toxicity, suggesting that CS-modified NPs can be used as carriers of anticancer drugs.

Promising positive liver targeting delivery system based on arabinogalactan-anchored polymeric micelles of norcantharidin

Liver cancer is the third most common cause of global cancer-related deaths. This study focused on newly developed drug delivery systems with hepatocyte asialoglycoprotein receptor binding targeting the liver. Although norcantharidin (NCTD) is effective in primary liver cancer treatment, its toxicity in the urinary system remains. Positive liver-targeting effect could be achieved by preparing polymer micelles by arabinogalactan on the surface of N-(4-methylimidazole)-hydroxyethyl-chitosan (MHC). HepG2 cells were used to analyze the cytotoxicity, invasion, apoptosis and uptake of NCTD-loaded micelles. The in vivo antitumor efficacy of NCTD-M was evaluated using tumor-bearing nude mice. Successful preparation of NCTD-M was shown. In vivo imaging showed that micelles significantly increased positive liver drug targeting. Laser confocal microscopy showed increased cellular uptake of micelles. NCTD-M also enhanced cell invasion and the proportion of apoptotic cells. Compared with the other groups, the micelles showed better antitumor effects in vivo. Therefore, the positive liver-targeting NCTD-M, which can enhance antitumor efficacy and reduce toxicity, could be a promising and effective therapeutic agent for liver cancer treatment.

Extraction, characterization and antioxidant activities of pumpkin polysaccharide

Extraction and antioxidant activities of polysaccharide from pumpkin were discussed. The crude polysaccharide was extracted with the hot water. It showed that the calcium chloride (CaCl₂) method was ideal for deproteinization. The pumpkin polysaccharide was linked by the α/β-glycosidic bond, and it might contain acetyl groups. Pumpkin polysaccharide was heteropolysaccharide composed of six monosaccharides. In addition, it indicated that pumpkin polysaccharide exhibited good antioxidant activities.