High-sensitivity humidity sensing of a U-shaped microfiber coated with porous methacryloxyethyl trimethyl ammonium chloride film.

We demonstrate an intensity-modulated humidity sensor based on a U-shaped microfiber coated with porous methacryloxyethyl trimethyl ammonium chloride (DMC) film. The high surface-to-volume ratios of the porous structure improve the interaction between the DMC film and water molecules, resulting in significantly enhanced sensitivity of the humidity sensor. In the humidity range of 34.0%RH to 50.0%RH, the humidity sensitivity of this microfiber sensor is up to 3.090 dB/%RH, which is six times higher than that of other fiber humidity sensors. The humidity detection range can be adjusted with high humidity sensitivity (≥1.685d B/% R H) by controlling the microfiber diameter and bent diameter. Furthermore, this type of sensor has a fast recovery time of 0.023 s and a response time of only 0.692 s. This type of sensor has broad potential applications in chemical processing, medical diagnostics, instrument manufacturing, and so on.

Gastrin-releasing peptide receptor-targeted gadolinium oxide-based multifunctional nanoparticles for dual magnetic resonance/fluorescent molecular imaging of prostate cancer.

Bombesin (BBN), an analog of gastrin-releasing peptide (GRP), specifically binds to GRP receptors, which are overexpressed in human prostate cancer (PC). Here, we synthesized a BBN-modified gadolinium oxide (Gd2O3) nanoprobe containing fluorescein (Gd2O3-5(6)-carboxyfluorescein [FI]-polyethylene glycol [PEG]-BBN) for targeted magnetic resonance (MR)/optical dual-modality imaging of PC. The Gd2O3-FI-PEG-BBN nanoparticles exhibited a relatively uniform particle size with an average diameter of 52.3 nm and spherical morphology as depicted by transmission electron microscopy. The longitudinal relaxivity (r1) of Gd2O3-FI-PEG-BBN (r1 =4.23 mM-1s-1) is comparable to that of clinically used Magnevist (Gd-DTPA). Fluorescence microscopy and in vitro cellular MRI demonstrated GRP receptor-specific and enhanced cellular uptake of the Gd2O3-FI-PEG-BBN in PC-3 tumor cells. Moreover, Gd2O3-FI-PEG-BBN showed more remarkable contrast enhancement than the corresponding nontargeted Gd2O3-FI-PEG according to in vivo MRI and fluorescent imaging. Tumor immunohistochemical analysis further demonstrated improved accumulation of the targeted nanoprobe in tumors. BBN-conjugated Gd2O3 may be a promising nanoplatform for simultaneous GRP receptor-targeted molecular cancer diagnosis and antitumor drug delivery in future clinical applications.

Organic Radical Contrast Agents Based on Polyacetylenes Containing 2,2,6,6-Tetramethylpiperidine 1-Oxyl (TEMPO): Targeted Magnetic Resonance (MR)/Optical Bimodal Imaging of Folate Receptor Expressing HeLa Tumors in Vitro and in Vivo(a).

Nitroxides have great potential as magnetic resonance imaging (MRI) contrast agents for tumor detection. Polyacetylenes(PAs) containing 2,2,6,6-tetramethyl-piperidine oxyl (TEMPO) and poly(ethylene glycol) were synthesized via metathesis polymerization of the corresponding substituted acetylenes to be used for targeted bimodal MRI /optical imaging of tumors. The poly(ethylene glycol) in the polyacetylenes enables covalent conjugation of carboxyl fluorescein and folic acid (FA) with hydroxyl groups to develop targeted multifunctional organic radical contrast agents (ORCAs). In vitro studies confirm the excellent binding specificity and subsequent enhanced cellular internalization of the targeted ORCAs (PA-TEMPO-FI-FA) without cytotoxicity. In vivo T1-weighted MRI demonstrates the active tumor targeting ability of PA-TEMPO-FI-FA to generate specific contrast enhancement in mice bearing HeLa tumors. Moreover, longitudinal optical imaging displays high tumor accumulation after 1 h post-injection of PA-TEMPO-FI-FA. These results indicate that multifunctional ORCAs may provide a tumor-targeted delivery platform for further molecular imaging guided cancer therapy.

[Live cell fluorescent imaging and cytotoxicity assessment of pH fluorescent probe based on styrylcyanine dyes].

OBJECTIVE: To prepare a pH fluorescence probe based on styrylcyanine dyes for live cell imaging. METHODS: The Probe 1 was prepared by reaction of 4-pyridinecarboxaldehyde with 1,1,2-trimethylbenz[e]indole. The influence of pH on the fluorescent properties was examined, and the cell viability was examined using cell counting kit-8. The Probe 1 was used as a pH fluorescence probe in living cell. RESULTS: Probe 1 emitted green fluorescence under neutral and basic conditions but orange fluorescence under acid condition. Probe 1 selectively stained the cytoplasmic regions of living cells without significantly affecting the cell viability. CONCLUSION: The pH-sensitive fluorescent probe prepared based on styrylcyanine possesses good ability of cell membrane permeation for live cell fluorescent imaging.