The performance of nanomaterials is intricately linked to their size and combination form. Quantum dots (QDs), for instance, exhibit unique electronic and quantum properties due to their size effect. Moreover, the optical and electronic attributes of QD assemblies can be tailored by adjusting the size of individual QDs and their spatial arrangement within the assembly. Thus, it is imperative to explore suitable and universally applicable methods to prepare adjustable QDs and their assemblies.

In a recent study, Akter et al. devised mesoscopic QD assemblies using a novel bio-catalytic nanoparticle shaping (BNS) approach. Specifically, the authors employed L-lysine as a linker to assemble CdSe/CdS QDs, initially yielding ultra-large QD assemblies. Subsequently, these assemblies were catalytically cleaved by trypsin, resulting in mesoscopic QD assemblies (ms-QD) with a size of 84 nm (Fig. 1A). Relative to single QDs, the redshift and weakened emission observed in the photoluminescence spectrum of ms-QD suggest the presence of internal emission reabsorption processes within the assembly, which holds promise for leveraging energy or electron/hole transfer processes in the production of new optical materials.

Fig 1. (A) Synthetic pathway of ms-QD by the BNS method and corresponding TEM image, and (B) the synthetic scheme of organic molecule assemblies. Reproduced from DOI: 10.1039/D4NH00134F with permission from the Royal Society of Chemistry.

Additionally, the authors synthesized and investigated nanoassemblies of the organic molecule tetrakis(4-carboxyphenyl)porphyrin (Fig. 1B) using a similar method. They observed significant differences in reactive oxygen generation under light among the various assemblies, indicating the potential to modulate the molecular function of the particle’s core unit by altering the composition of connecting molecules.

In summary, this method demonstrates high versatility and can be employed for preparing assemblies of both QDs and organic molecules. Furthermore, it allows for the replacement of biological enzymes/substrates as needed to generate various nanoassemblies with unique physicochemical properties for further applications.

To find out more, please read:

Bio-catalytic nanoparticle shaping for preparing mesoscopic assemblies of semiconductor quantum dots and organic molecules
Rumana Akter, Nicholas Kirkwood, Samantha Zaman, Bang Lu, Tinci Wang, Satoru Takakusagi, Paul Mulvaney, Vasudevanpillai Biju and Yuta Takano
Nanoscale Horiz., 2024, Advance Article

About the blogger

Chao Wang is a postdoctoral fellow at Oregon State University and a member of the Nanoscale Horizons Community Board. His research focuses on multiple nanomedicines (especially metal-organic frameworks) and their theranostics for cancer, endometriosis and stem cell tracking.

Currently, nanomaterials (NM) are attracting significant attention in the field of biomedicine. However, once these nanomaterials are utilized for in vivo treatments they interact with the surrounding physiological environment, leading to the adsorption of various biomolecules onto their surfaces, forming a biomolecular corona (BMC) and thereby influencing the performance and behavior of the nanomaterials. Presently, the in vitro studies of NM primarily involve dispersing the nanoparticles in 10% fetal bovine serum (FBS) and then evaluating their toxicity and therapeutic effects. However, this evaluation method is insufficient as it cannot accurately simulate the conditions of human blood. Moreover, this practical issue remains unresolved to date.

Fig 1. Schematic illustrating the molecular and biological biases arising from the well-known in vitro/in vivo mismatch in nanomedicine due to the biomolecular corona. Reproduced from DOI: 10.1039/D3NH00510K with permission from the Royal Society of Chemistry.

To validate the series of biases existing in established experimental practices and to advance the fields of nanomedicine and nanotoxicology, this study investigated two NM types with vastly different physicochemical properties commonly used in biomedicine. The research compared the molecular and biological biases resulting from the mismatch between NM dispersed in 10% FBS (utilized for in vitro biological assays) and whole human plasma (HP, closer to in vivo administration schemes). Through comparative analysis using proteomics, lipidomics, high-throughput multi-parameter in vitro screening, and single-molecule feature analysis, it was demonstrated that the dynamic changes in BMC composition are material dependent and that cell viability, transport pathways, and autophagic cascades are influenced by the presence or absence of pre-formed BMC corona. These findings underscore the potential limitations of NM in vitro testing in accurately representing real in vivo conditions. Therefore, it is necessary to establish new shared protocols to enhance the accuracy and predictive capability of NM testing.

In summary, this study confirms the biases that may exist when using standard in vitro conditions for NM toxicology assessments, reminding us of the need to establish a comprehensive experimental framework to generate and support new knowledge in the field of biologically relevant nanomaterial interactions. For instance, integrating advanced predictive tools such as artificial intelligence and machine learning will enable nanotoxicology and nanomedicine to progress towards personalized solutions for precision healthcare.

To find out more, please read:

Sources of biases in the in vitro testing of nanomaterials: the role of the biomolecular corona
Valentina Castagnola, Valeria Tomati, Luca Boselli, Clarissa Braccia, Sergio Decherchi, Pier Paolo Pompa, Nicoletta Pedemonte, Fabio Benfenati and Andrea Armirotti
Nanoscale Horiz., 2024, Advance Article

About the blogger

Fangfang Cao is a Research Fellow at National University of Singapore and a member of the Nanoscale Horizons Community Board. Dr Cao’s research focuses on nanocatalytic medicine and microbial therapy.