Bioprinting offers tremendous potential in the fabrication of functional tissue constructs for replacement of damaged or diseased tissues. Among other fabrication methods used in tissue engineering, bioprinting provides accurate control over the construct's geometric and compositional attributes using an automated approach. Bioinks are composed of the hydrogel material and living cells that are critical process variables in the fabrication of functional, mechanically robust constructs. Appropriate cells can be encapsulated in bioinks to create functional tissue structures. Ideal bioinks are required to undergo a sol–gel transition consuming minimal processing time, and a plethora of chemical and physical crosslinking mechanisms are generally exploited to achieve high shape fidelity and construct stability. In contrast, crosslinking of hydrogel material at rapid rates can cause nozzle clogging, and hence, optimization of the bioink is often necessary. Bioinks can be formulated using natural or synthetic biomaterials, alone or in combination of these biomaterials. Herein, the various bioprinting methods are discussed; the natural, synthetic, or hybrid materials used as bioinks are analyzed; and the challenges, limitations, and future directions concerning the bioprinting technique are appraised.

Iron oxide magnetic nanoparticles (IONPs) have attracted enormous attention because of their extensive medicinal and industrial applicability. PEGylated L-arginine modified iron oxide magnetic nanoparticles (PEG-Arg@IONPs) were synthesized and functioned in the present research as MRI contrast agents considered in vivo BALB/c model. The Synthesized PEG-Arg@IONPs were tracked in certain time intervals by MRI. The intensity of MR imaging of kidneys increased after administration of PEG-Arg@IONPs, which could confirm the emission of these nanoparticles by kidneys shortly after administration. Although PEG-Arg@IONPs were uptake by liver within 2 hours after injection, whereas, the signal change intensity of spleen, heart and kidneys confirmed that PEG-Arg@IONPs existed in other organs. The results illustrated that IONPs coated with PEGylated natural amino acid thin layers had a long circulation time and could be served as T₂ contrast agents for diagnosis purpose. Notably, to the best of our knowledge, it was the first time the biocompatibility and biodegradability of IONPs was studied and evaluated by stereological and MRI technique.

We report the synthesis of iron oxide magnetic nanoparticles (IONPs) coated with various natural amino acids (AAs) using a one‐pot reaction in an aqueous medium. Several AAs, which contained hydrophilic and hydrophobic groups, were selected to study their effects on size, morphology and toxicity of IONPs. Functionalized IONPs were characterized using X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning and transmission electron microscopies. Furthermore, vibrating sample magnetometry analysis shows these nanoparticles have excellent magnetic properties. Cellular toxicity of IONPs was also investigated on HFF2 cell lines. The AA‐coated IONPs are non‐toxic and biocompatible. Natural AA‐coated IONPs show a potential for their development in in vitro and in vivo biomedical fields due to their non‐toxicity, good ζ ‐potential and related small size and narrow size distribution.

Radiation therapy has demonstrated promising effectiveness against several types of cancers. X-ray radiation therapy can be made further effective by utilizing nanoparticles of high-atomic-number (high-Z) materials that act as radiosensitizers. Here, in purpose of maximizing the radiation therapy within tumors, bovine serum albumin capped gadolinium oxide and gold nanoparticles (Gd₂O₃@BSA-Au NPs) are developed as a bimetallic radiosensitizer. In this study, we incorporate two high-Z-based nanoparticles, Au and Gd, in a single nanoplatform. The radiosensitizing ability of the nanoparticles was assessed with a series of in vitro tests, following evaluation in vivo in a breast cancer murine model. Enhanced tumor suppression is observed in the group that received radiation after administration of Gd₂O₃@BSA-Au NPs. As a result, cancer therapy efficacy is significantly improved by applying Gd₂O₃@BSA-Au NPs under X-ray irradiation, as evidenced by studies evaluating cell viability, proliferation, reactive oxygen species production, and in vivo anti-tumor effect.