Rapid hybridization of chitosan-gold-antibodies via metal-free click in water-based systems: a model approach for naked-eye detectable antigen sensors

Brush-Structured Chitosan/PolyHEMA with Thymine and Its Synergistic Effect on the Specific Interaction with ssDNA and Cellular Uptake

Cationic polymers are known to attach on an anionic cell surface and favor gene transportation/transfection into the cells. However, when the positive charges accumulate, they tend to cause cell damage and delivery failure. Chitosan (CS) is a potential cationic bio-derived polymer whose chemical structures can be modified to fine-tune the charges as well as the add-on functions. The present work demonstrates (i) the decoration of a nucleic acid sequence-like brush structure on CS to allow the specific interaction with DNA and (ii) delivery into the cell. By simply applying mercaptoacetic acid as the chain transfer agent, the grafting of poly(hydroxyethyl methacrylate) (PHEMA) containing Thy (P(HEMA-Thy)) on CS is possible. The brush-like P(HEMA-Thy) leads Thy moieties to be in sequences. The Thy sequences perform as poly[T] for the specific interaction with ssDNA. The synergistic effect of CS and Thy sequences, i.e., electrostatic and base pairing interactions, results in an effective and efficient binding with ssDNA as well as significant delivery, especially in cellular uptake and cell viability. The use of CS in combination with Thy sequences in brush-like structures on CS is a model for other polysaccharides to be conjugated with the as-designed nucleic acid sequences for potential gene delivery.

Anti-CD24 bio Modified PEGylated Gold Nanoparticles as Targeted Computed Tomography Contrast Agent

Purpose: Molecular imaging is one of the import methods for recognition of cancer at the early stage in order to enhance the capacity of remedy. This study was aimed to introduce a new contrast agent that was targeted with CD24 so as to improve the CT scan detection of cancer cells with higher CD24 expression. Methods: The surface modifications of gold nanoparticles (Au-NPs) were done with long PEG (HS-PEG-CH3O) and short PEG (HS-PEG-COOH) chains to enhance their stability and capacity for immobilization of different antibodies. MTT assay was carried out to assess the biocompatibility of the NPs. The obtained contrast agent was implemented in the targeted CT imaging based on in vitro and in vivo studies of breast cancer. Results: The results revealed that the attached CD24 to the cell surface of PEGylated Au-NPs could enhance significantly the cells CT number (40.45 HU in 4T1, while it was 16.61 HU in CT26) It was shown that the attenuation coefficient of the molecularly targeted cells was more than 2 times excessive than the control groups. Further, the tumor region in model of xenograft tumor has higher density compare to the omnipaque groups, 60 min after injection (45 Hu vs.81 Hu). These results showed that the nanoparticles stayed in tumor region for longer time. Conclusion: It is predicted that the synthesized nanoparticle can be used as computed tomography contrast agent. Also, it can be used to identify the tumor cells with higher expression of CD24 at the early stages more efficiently compare to the other routine methods.

Chitosan Derivatives: Introducing New Functionalities with a Controlled Molecular Architecture for Innovative Materials

The functionalization of polymeric substances is of great interest for the development of innovative materials for advanced applications. For many decades, the functionalization of chitosan has been a convenient way to improve its properties with the aim of preparing new materials with specialized characteristics. In the present review, we summarize the latest methods for the modification and derivatization of chitin and chitosan under experimental conditions, which allow a control over the macromolecular architecture. This is because an understanding of the interdependence between chemical structure and properties is an important condition for proposing innovative materials. New advances in methods and strategies of functionalization such as the click chemistry approach, grafting onto copolymerization, coupling with cyclodextrins, and reactions in ionic liquids are discussed.