Development of the fluorescent carbon nanosensor for pH and temperature of liquid media with artificial neural networks

Intrinsic dual emissive insulin capped Au/Ag nanoclusters as single ratiometric nanoprobe for reversible detection of pH and temperature and cell imaging

pH and temperature are two important characteristics in cells and the environment. These, not only in the well-done regulation of cell functions but also in diagnosis and treatment, have a key role. Protein-protected bimetallic nanoclusters are abundantly used in the building of biosensors. However, insulin-stabilized Au-Ag nanoclusters with dual intrinsic emission have not been investigated yet. In this work, Dual emissive insulin templated Au-Ag nanocluster (Ins(Au/Ag)NCs) were first synthesized in a simple and green one-put manner. The two emission wavelengths of, as-prepared NCs centered at 410 and 630 nm, excited in one excitation wavelength (330 nm). These two emission peaks were assigned to the di-Tyrosine cross-linked formation and bimetallic nanoclusters respectively. Further analysis displayed that each emission band of Ins(Au/Ag)NCs responded to one variable whilst another peak remained constant; For blue and red emission wavelengths, pH dependency and thermo-responsibility were observed respectively. As-prepared nanoprobe with the intrinsic dual emissive feature was used for ratiometric determination of these parameters, each with a discrete response from another. The linear range of 6.0-9.0 for pH and 1 to 71 °C for temperature was obtained, which comprises the physiological range of pH and temperature and afforded intracellular sensing and imaging capability. As-prepared NCs probe show excellent biocompatibility and cell membrane permeability, and so were successfully applied as direct ratiometric pH and temperature probes in HeLa and HFF cells. More interestingly, this dual emissive nanoprobe is capable of distinguishing cancer cells from normal ones.

Using Recurrent Neural Networks to Reconstruct Temperatures from Simulated Fluorescent Data for use in Bio-Microfluidics

Many biological systems have a narrow temperature range of operation, meaning high accuracy and spatial distribution level are needed to study these systems. Most temperature sensors cannot meet both the accuracy and spatial distribution required in the microfluidic systems that are often used to study these systems in isolation. This paper introduces a neural network called the Multi-Directional Fluorescent Temperature Long Short-Term Memory Network (MFTLSTM) that can accurately calculate the temperature at every pixel in a fluorescent image to improve upon the standard fitting practice and other machine learning methods use to relate fluorescent data to temperature. This network takes advantage of the nature of heat diffusion in the image to achieve an accuracy of ±0.0199 K RMSE within the temperature range of 298K to 308 K with simulated data. When applied to experimental data from a 3D printed microfluidic device with a temperature range of 290 K to 380 K, it achieved an accuracy of ±0.0684 K RMSE. These results have the potential to allow high temperature resolution in biological systems than is available in many microfluidic devices.

All-in-One Photoactivated Inhibition of Butyrylcholinesterase Combined with Luminescence as an Activation and Localization Indicator: Carbon Quantum Dots@Phosphonate Hybrids

Photopharmacology is a booming research area requiring a new generation of agents possessing simultaneous functions of photoswitching and pharmacophore. It is important that any practical implementation of photopharmacology ideally requires spatial control of the medicinal treatment zone. Thus, advances in the study of substances meeting all the listed requirements will lead to breakthrough research in the coming years. In this study, CQDs@phosphonate nanohybrids are presented for the first time and combine biocompatible and nontoxic luminescent carbon quantum dots (CQDs) with photoactive phosphonate enabling inhibition of butyrylcholinesterase (BChE), which is a prognostic marker of numerous diseases. The conjunction of these components in hybrids maintains photoswitching and provides enhancement of BChE inhibition. After laser irradiation with a wavelength of 266 nm, CQDs@phosphonate hybrids demonstrate a drastic increase of butyrylcholinesterase inhibition from 38% up to almost 100% and a simultaneous luminescence decrease. All the listed hybrid properties are demonstrated not only for in vitro experiments but also for complex biological samples, i.e., chicken breast. Thus, the most important achievement is the demonstration of hybrids characterized by a remarkable combination of all-in-one properties important for photopharmacology: (i) bioactivity toward butyrylcholinesterase inhibition, (ii) strong change of inhibition degree as a result of laser irradiation, luminescence as an indicator of (iii) bioactivity state, and of (iv) spatial localization on the surface of a sample.

High sensitivity and wide range chlorophyll-a determination by simultaneous measurement of absorbance and fluorescence using a linear CCD

In the determination of chlorophyll with the fluorescence method in the natural water, the suspended particles and colloids will seriously interfere with the incident light and the fluorescence. Based on the analysis of the interaction between light and the measured substances, a high sensitivity, wide range of chlorophyll-a concentration measurement strategy, which combines optical information of fluorescence and absorbance with the CCD integration time transformation method, is proposed. Correspondingly, a novel algorithm, which can significantly correct the attenuation of incident light due to the absorption of suspended particles and the deviation of detected fluorescence caused by the scattered light and reflected light, is proposed to realize turbidity compensation. For verification, a self-designed compact optical experimental device consisting of a single LED and a linear CCD was set up to obtain the fluorescence spectrum and absorbance spectrum simultaneously. The experimental results demonstrate that the compensation strategy can commendably compensate for the impact of the suspended particles. The relative error of chlorophyll-a measurement is less than 5%, even in a high turbidity environment. Furthermore, the minimum detection limit is significantly reduced from conventional 0.01 μg/L to 0.0025 μg/L in the range of 0.0025-130 μg/L with the CCD integration time transformation method, which improves the measurement sensitivity. This device and method have the potential to be applied to the in situ online measurement of chlorophyll-a concentration in natural water.