Oligochitosan-stabilized photoluminescent gold nanoconstructs for optical bioimaging

Biodistribution of Multimodal Gold Nanoclusters Designed for Photoluminescence-SPECT/CT Imaging and Diagnostic

Highly biocompatible nanostructures for multimodality imaging are critical for clinical diagnostics improvements in the future. Combining optical imaging with other techniques may lead to important advances in diagnostics. The purpose of such a system would be to combine the individual advantages of each imaging method to provide reliable and accurate information at the site of the disease bypassing the limitations of each. The aim of the presented study was to evaluate biodistribution of the biocompatible technetium-99m labelled bovine serum albumin-gold nanoclusters (^99mTc-BSA-Au NCs) as photoluminescence-SPECT/CT agent in experimental animals. It was verified spectroscopically that radiolabelling with ^99mTc does not influence the optical properties of BSA-Au NCs within the synthesized ^99mTc-BSA-Au NCs bioconjugates. Biodistribution imaging of the ^99mTc-BSA-Au NCs in Wistar rats was performed using a clinical SPECT/CT system. In vivo imaging of Wistar rats demonstrated intense cardiac blood pool activity, as well as rapid blood clearance and accumulation in the kidneys, liver, and urinary bladder. Confocal images of kidney, liver and spleen tissues revealed no visible uptake indicating that the circulation lifetime of ^99mTc-BSA-Au NCs in the bloodstream might be too short for accumulation in these tissues. The cellular uptake of ^99mTc-BSA-Au NCs in kidney cells was also delayed and substantial accumulation was observed only after 24-h incubation. Based on our experiments, it was concluded that ^99mTc-BSA-Au NCs could be used as a contrast agent and shows promise as potential diagnostic agents for bloodstream imaging of the excretory organs in vivo.

Tb-doped BSA-gold nanoclusters as a bimodal probe for the selective detection of TNT

Trinitrotoluene (TNT) is a widely used explosive belonging to the family of nitroaromatic compounds, and its misuse poses a significant threat to society. Herein, we propose a Tb-BSA-AuNC fluorescent and colorimetric sensing probe for the selective onsite detection of TNT in the aqueous phase. Tb-doped BSA-protected gold nanoclusters (Tb-BSA-AuNCs) were synthesized by a microwave-assisted method, and TNT detection was carried out utilizing the chemistry of Meisenheimer complex formation. Tb doping of gold nanoclusters was demonstrated to facilitate better electron shuttling effects and thereby improve the efficiency of complex formation between the TNT and gold nanoclusters. A paper strip assay was also developed for TNT detection with the designed probe. Limits of detection and quantification of 0.2136 mM and 0.7120 mM, respectively, were achieved. Graphical abstract.

The appliances and prospects of aurum nanomaterials in biodiagnostics, imaging, drug delivery and combination therapy

Aurum nanomaterials (ANM), combining the features of nanotechnology and metal elements, have demonstrated enormous potential and aroused great attention on biomedical applications over the past few decades. Particularly, their advantages, such as controllable particle size, flexible surface modification, higher drug loading, good stability and biocompatibility, especially unique optical properties, promote the development of ANM in biomedical field. In this review, we will discuss the advanced preparation process of ANM and summarize their recent applications as well as their prospects in diagnosis and therapy. Besides, multi-functional ANM-based theranostic nanosystems will be introduced in details, including radiotherapy (RT), photothermal therapy (PTT), photodynamic therapy (PDT), immunotherapy (IT), and so on.

Stability improvement and characterization of bioprinted pectin-based scaffold

Purpose:

Bioprinting is an alternative method for constructing tissues/organs for transplantation. This study investigated the cross-linker influence and post-printing modification using oligochitosan and chitosan for stability improvement.

Methods:

Oligochitosan was tested as a novel cross-linker to replace Ca2+ for pectin-based bio-ink. Oligochitosan (2 kD) and different molecular weight of chitosan were used to modify the bioprinted scaffold. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to characterize the scaffolds.

Results:

Oligochitosan failed to serve as a viable cross-linker. Successful post-printing modification was confirmed by FTIR and SEM analyses.

Conclusion:

Regarding post-modification, chitosan-treated scaffolds showed enhanced stability compared to untreated scaffolds. In particular, scaffolds modified with 150 kD chitosan exhibited the highest stability.

Two-dimensional material-based bionano platforms to control mesenchymal stem cell differentiation

Background

In the past decade, stem cells, with their ability to differentiate into various types of cells, have been proven to be resourceful in regenerative medicine and tissue engineering. Despite the ability to repair damaged parts of organs and tissues, the use of stem cells still entails several limitations, such as low differentiation efficiency and difficulties in guiding differentiation. To address these limitations, nanotechnology approaches have been recently implemented in stem cell research. It has been discovered that stem cells, in combination with carbon-based functional materials, show enhanced regenerative performances in varying biophysical conditions. In particular, several studies have reported solutions to the conventional quandaries in biomedical engineering, using synergetic effects of nanohybrid materials, as well as further development of technologies to recover from diverse health conditions such as bone fracture and strokes.

Main text

In this review, we discuss several prior studies regarding the application of various nanomaterials in controlling the behavior of stem cells. We focus on the potential of different types of nanomaterials, such as two-dimensional materials, gold nanoparticles, and three-dimensional nanohybrid composites, to control the differentiation of human mesenchymal stem cells (hMSCs). These materials have been found to affect stem cell functions via the adsorption of growth/differentiation factors on the surfaces of nanomaterials and the activation of signaling pathways that are mostly related to cell adhesion and differentiation (e.g., FAK, Smad, Erk, and Wnt).

Conclusion

Controlling stem cell differentiation using biophysical factors, especially the use of nanohybrid materials to functionalize underlying substrates wherein the cells attach and grow, is a promising strategy to achieve cells of interest in a highly efficient manner. We hope that this review will facilitate the use of other types of newly discovered and/or synthesized nanomaterials (e.g., metal transition dichalcogenides, non-toxic quantum dots, and metal oxide frameworks) for stem cell-based regenerative therapies.