Search

Nanodiamonds have acknowledged growing attention due to their facile functionalization, stable fluorescence, low toxicity, and decent biocompatibility. However, despite advances applications of nanodiamonds in drug delivery, catalysis and bio-sensing, laser irradiation still limits long-time tracking of nanodiamonds in living cells due to phototoxicity. Here, using optical diffraction tomography, we performed quantitative morphological and biophysical analysis of living cells via endocytosis or electroporation of nanodiamonds (5 nm, 35 nm, and 100 nm) without the need for a fluorescence label. Optical diffraction tomography is an inexpensive and noninvasive microscopy technique, which images cells and subcellular structures as a function of their refractive index. The laser excitation power is much weaker than in the case of fluorescence microscopy, which reduces phototoxicity. Thanks to the very high refractive index of diamond, nanodiamonds in HeLa cells can be clearly discriminated from cellular structures using optical diffraction tomography. As an application, we show that aggregation and deaggregation of internalized nanodiamonds can be detected via changes in the refractive index distribution of the entire cell. Optical diffraction tomography successively images prevention of in-cell particle aggregation through polyglycerol coating of nanodiamonds. In the case of endocytosis, optical diffraction tomography shows deaggregation of nanodiamonds after a prolonged incubation time. Together, our findings implicate that refractive index measurements are a favorable tool to track nanodiamonds, without a fluorescent label, inside living cells. This could be useful to study real-time therapeutic or metabolic activities in living cells using very weak laser irradiation. Finally, the elaborate creation of fluorescent defects in nanodiamonds becomes redundant.

Introducing nanomaterial in interfacial polymerization (IP) system for nanofiltration (NF) membrane synthesis has witnessed a remarkable performance enhancement thus drawing intensive attention. However, the underlying mechanism for nanomaterial induced performance enhancement is still unclear due to the lack of study on nanoparticle dispersity and architecture at polymerization interface. Using nanodiamond (ND) as the example, this study demonstrates nanoparticle undergoes aggregation preferably at the reaction interface and the architecture of ND particles has a direct impact on membrane structure and performance. Through proactively controlling the aggregation extent while employing these ND clusters as the nano-template, the feature morphology of NF membrane is transformed from nodules to ridges at the nanoscale. Such transformation generates a significant augmentation of effective membrane area, leading to the increase of water permeance by 70%. With a low amount of nanodiamond addition (

Background Nanodiamonds (NDs) provide a unique multitasking system for drug delivery and fluorescent imaging in biological environments. Owing to their quantum properties, NDs are expected to be employed as multifunctional probes in the future for the accurate visualization of biophysical parameters such as temperature and magnetic fields. However, the use of NDs for the selective targeting of the biomolecules of interest within a complicated biological system remains a challenge. One of the most promising solutions is the appropriate surface design of NDs based on organic chemistry and biochemistry. The engineered NDs have high biocompatibility and dispersibility in a biological environment and hence undergo cellular uptake through specific pathways. Scope of review This review focuses on the selective targeting of NDs for biomedical and biophysical applications from the viewpoint of ND surface functionalizations and modifications. These pretreatments make possible the specific targeting of biomolecules of interest on or in a cell by NDs via a designed biochemical route. Major conclusions The surface of NDs is covalently or noncovalently modified with silica, polymers, or biomolecules to reshape them, control their size, and enhance the colloidal stability and biomolecular selectivity toward the biomolecules of interest. Electroporation, chemical treatment, injection, or endocytosis are the methods generally adopted to introduce NDs into living cells. The pathway, efficiency, and the cell viability depend on the selected method. General significance In the biomedical field, the surface modification facilitates specific delivery of a drug, leading to a higher therapeutic efficacy. In biophysical applications, the surface modification paves the way for the accurate measurement of physical parameters to gain a better understanding of various cell functions.