The Diamond Concept Enigma: Recent Trends of Its Implementation in Cross-linked Chitosan-Based Scaffolds for Bone Tissue Engineering

An increasing number of publications over the past ten years have focused on the development of chitosan-based cross-linked scaffolds to regenerate bone tissue. The design of biomaterials for bone tissue engineering applications relies heavily on the ideals set forth by a polytherapy approach called the "Diamond Concept". This methodology takes into consideration the mechanical environment, scaffold properties, osteogenic and angiogenic potential of cells, and benefits of osteoinductive mediator encapsulation. The following review presents a comprehensive summarization of recent trends in chitosan-based cross-linked scaffold development within the scope of the Diamond Concept, particularly for nonload-bearing bone repair. A standardized methodology for material characterization, along with assessment of in vitro and in vivo potential for bone regeneration, is presented based on approaches in the literature, and future directions of the field are discussed.

Multifunctional chitosan ferrogels for targeted cancer therapy by on-demand magnetically triggered drug delivery and hyperthermia

A facile method for the synthesis of chitosan ferrogels for magnetically triggered drug release and hyperthermia treatment is presented. The glyoxal crosslinked, dried ferrogels (magnetic bioaerogels) have been characterized by FTIR, XRD, TGA and VSM analyses and they possess unique characteristics such as high porosity, ultra-low density and superparamagnetism (M_s up to 56 emu g^-1). In addition, they present high drug (Doxorubicin, DOX) loading efficiency (~40 %), tumor-specific pH-responsive swelling, excellent biodegradation, remotely switchable drug release and high magnetic hyperthermia potential (42 °C within 4 min). Almost complete degradation of the ferrogels occurs in 3 months under physiological conditions (pH = 7.4), while the tumor-specific microenvironment (pH = 5.6) accelerates the degradation rate, where it occurs in ~8 weeks. Furthermore, an enhancement in drug release (by 30 %) was observed in 60 min, when subjected to a magnetic field of 50 mT. Excellent biocompatibility and promising cell-material interactions have been exhibited by the ferrogels, substantiated by MTT assay, cytoskeleton staining and confocal imaging. The viability has been drastically reduced for DOX-loaded samples due to the action of the released drug; validating the efficacy of DOX loaded ferrogels. The system presented, therefore, holds multi-functionalities enabling smart cancer treatment.