Nanoparticles hold great potential in contributing to high-resolution bioimaging as well as for biomedical applications. Although, selenium (Se) nanoparticles (NPs) have been investigated owing to their potential roles in therapeutics, the imaging capability of these NPs has never been explored. This manuscript identifies the intrinsic fluorescence of Se NPs, which is highly beneficial for nanoscale imaging of biological structures. The emission of individual NPs and its evolution with time is explored. The photoluminescence spectra has revealed visible to near infrared emission for Se NPs. The work finally reflects on the role of this intrinsic fluorescence for in vitro imaging and tracking in fibroblast cells, without the need of any additional tags. This technique would overcome the limitations of the conventionally used methods of imaging with tagged fluorescent proteins and dyes, preventing possible adverse cellular effects or phototoxicity caused by the added fluorescent moieties.

The detection and identification of biomolecules are essential in the modern era of medical diagnostics. Several approaches have been established, but they have significant limitations such as laborious and time-consuming sample preparation, analysis, and the need to use external probes which provide adequate but not desired levels of accuracy and sensitivity. Herein, we have explored successfully a non-invasive technique to detect and identifybiomolecules such as amino acids and proteins by utilizing their intrinsic fluorescence. The developed confocal microscopy method revealed high and photostable emission counts of these biomolecules including amino acids (tryptophan, phenylalanine, tyrosine, proline, histidine, cysteine, aspartic acid, asparagine, isoleucine, lysine, glutamic acid, arginine) and proteins (HSA, BSA) when they are excited with a green laser. The fluorescence lifetime of the samples enabled the identification and distinction of known and blind samples of biomolecules from each other. The developed optical technique is straightforward, non-destructive and does not require laborious labeling to identify specific proteins, and may serve as the basis for the development of a device that would quickly and accurately identify proteins at an amino acid level. Therefore, this approach would open an avenue for precise detection in imaging and at the same time increases our understanding of chemical dynamics at the molecular level.

Nanoparticle (NP) based technologies have proved to be considerably beneficial for advances in biomedicine especially in the areas of disease detection, drug delivery and bioimaging. Over the last few decades, NPs have garnered interest for their exemplary impacts on the detection, treatment, and prevention of cancer. The full potential of these technologies are yet to be employed for clinical use. The ongoing research and development in this field demands single multifunctional composite materials that can be employed simultaneously for drug delivery and biomedical imaging. In this manuscript, a unique combination of silk fibroin (SF) and nanodiamonds (NDs) in the form of nanospheres are fabricated and investigated. The spheres were loaded with the anthracyline Doxorubicin (DoX) and the drug release kinetics for these ND-SF-DoX (NDSX) spheres were studied. NDs provided the fluorescence modality for imaging while the degradable SF spheres stabilized and released the drug in a controlled manner. The emission and structural properties of the spheres were characterized during drug release. The degradability of SF and the subsequent release of DoX from the spheres were monitored through fluorescence of NDs inside the spheres. This research demonstrates the enormous potential of the ND-SF nanocomposite platforms for diagnostic and therapeutic purposes, which are both important for pharmaceutical research and clinical settings.

Imaging of biological matter by using fluorescent nanoparticles (NPs) is becoming a widespread method for in vitro imaging. However, currently there is no fluorescent NP that satisfies all necessary criteria for short-term in vivo imaging: biocompatibility, biodegradability, photostability, suitable wavelengths of absorbance and fluorescence that differ from tissue auto-fluorescence, and near infrared (NIR) emission. In this paper, we report on the photoluminescent properties of magnesium oxide (MgO) NPs that meet all these criteria. The optical defects, attributed to vanadium and chromium ion substitutional defects, emitting in the NIR, are observed at room temperature in NPs of commercial and in-house ball-milled MgO nanoparticles, respectively. As such, the NPs have been successfully integrated into cultured cells and photostable bright in vitro emission from NPs was recorded and analyzed. We expect that numerous biotechnological and medical applications will emerge as this nanomaterial satisfies all criteria for short-term in vivo imaging.