Self-illumination of Carbon Dots by Bioluminescence Resonance Energy Transfer

Crosslinked modified decellularized rabbit conjunctival stroma for reconstruction of tissue-engineered conjunctivain vitro

Conjunctival reconstruction is an essential part of ocular surface restoration, especially in severe conjunctival disorders. Decellularized conjunctival tissues have been used in tissue engineering. In this study, we investigated the feasibility of constructing tissue-engineered conjunctiva using stem cell (human amniotic epithelial cells, hAECs), and cross-linked modified decellularized rabbit conjunctival stroma (DRCS-Asp-hEGF), and decellularized rabbit conjunctiva stroma (DRCS). With phospholipase A2 and sodium dodecyl, DRCS were nearly DNA-free, structurally intact and showed no cytotoxic effectsin vitro, as confirmed by DNA quantification, histology, and immunofluorescence. The results of Fourier transform infrared, Alcian blue staining and human epidermal growth factor (hEGF) release assays showed that DRCS-Asp-hEGF was successfully prepared via crosslinking with aspartic acid (Asp) and modified by hEGF at pH 7.7. The hAECs were positive for octamer-binding transcription factor-4 and ABCG2 cell markers. The hAECs were directly placed on the DRCS and DRCS-Asp-hEGF for five days respectively. Tissue-engineered conjunctiva was constructedin vitrofor five days, and the fluorescence staining results showed that hAECs grew in monolayers on DRCS-Asp-hEGF and DRCS. Flow cytometry results showed that compared with DRCS, the number of apoptotic cells stained in DRCS-Asp-hEGF was small, 86.70 ± 0.79% of the cells survived, and 87.59 ± 1.43% of the cells were in the G1 phase of DNA synthesis. Electron microscopy results showed that desmosome junction structures, which were similar to the native conjunctival tissue, were formed between cells and the matrix in the DRCS-Asp-hEGF.

Rapid detection of tear lactoferrin for diagnosis of dry eyes by using fluorescence polarization-based aptasensor

Differentiating dry eye disease (DED) from allergic or viral conjunctivitis rapidly and accurately is important to ensure prompt diagnosis and treatment. Tear lactoferrin (LF), a multi-functional glycoprotein found in tears, decreases significantly in patients with DED, and has been considered as a DED diagnostic biomarker. Measuring tear LF level, however, takes time and requires the use of bulky instruments. Herein, a homogeneous carbon nanostructure-based aptasensor with high sensitivity and selectivity has been developed by applying fluorescence polarization (FP) technology. The FP of carbon dots (CDs) bioconjugated with LF aptamers (CDs-aptamer) is 21.2% higher than that of CDs, which can be further amplified (1.81 times) once interacting with graphene oxide nanosheets (GONS). In the presence of LF, GONS separates from CDs-aptamer because of the stronger binding affinity between CDs-aptamer to LF, resulting in the decrease of FP value. A linear relationship is observed between FP value and LF concentration in spiked tear samples from 0.66 to 3.32 mg/mL. The selectivity of the aptasensor has been investigated by measuring other proteins. The results indicate that the FP-based aptasensor is a cost-effective method with high sensitivity and selectivity in detection of tear LF.

Coelenterazine-Dependent Luciferases as a Powerful Analytical Tool for Research and Biomedical Applications

: The functioning of bioluminescent systems in most of the known marine organisms is based on the oxidation reaction of the same substrate-coelenterazine (CTZ), catalyzed by luciferase. Despite the diversity in structures and the functioning mechanisms, these enzymes can be united into a common group called CTZ-dependent luciferases. Among these, there are two sharply different types of the system organization-Ca2+-regulated photoproteins and luciferases themselves that function in accordance with the classical enzyme-substrate kinetics. Along with deep and comprehensive fundamental research on these systems, approaches and methods of their practical use as highly sensitive reporters in analytics have been developed. The research aiming at the creation of artificial luciferases and synthetic CTZ analogues with new unique properties has led to the development of new experimental analytical methods based on them. The commercial availability of many ready-to-use assay systems based on CTZ-dependent luciferases is also important when choosing them by first-time-users. The development of analytical methods based on these bioluminescent systems is currently booming. The bioluminescent systems under consideration were successfully applied in various biological research areas, which confirms them to be a powerful analytical tool. In this review, we consider the main directions, results, and achievements in research involving these luciferases.