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.
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 (Gd
2
O
3
) nanoprobe containing fluorescein (Gd
2
O
3
-5(6)-carboxyfluorescein [FI]-polyethylene glycol [PEG]-BBN) for targeted magnetic resonance (MR)/optical dual-modality imaging of PC. The Gd
2
O
3
-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 (r
1
) of Gd
2
O
3
-FI-PEG-BBN (r
1
=4.23 mM
−1
s
−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 Gd
2
O
3
-FI-PEG-BBN in PC-3 tumor cells. Moreover, Gd
2
O
3
-FI-PEG-BBN showed more remarkable contrast enhancement than the corresponding nontargeted Gd
2
O
3
-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 Gd
2
O
3
may be a promising nanoplatform for simultaneous GRP receptor-targeted molecular cancer diagnosis and antitumor drug delivery in future clinical applications.
We demonstrate an ultrafast humidity micro-fiber sensor based on molybdenum disulfide (MoS2) cladding with three dimensional network structure. The high surface-to-volume rations and porous mesh structure improve the interaction of between MoS2 and water molecules, further enhancing the performance of the humidity sensor. The results demonstrated that the sensor can perform in a wide relative humidity (RH) range between 10%RH to 90%RH with rapid dynamic behavior (response and recovery time are 0.090 and 0.130 s respectively). The sum of response and recovery time (total time) is 0.220 s, which is the fastest in the reported MoS2-based humidity sensors. The sensitivity of this sensor is up to -1.501 dB/%RH in the RH range (77%RH–90%RH). Such a high performance RH sensor will have a wide range of application potential in chemical processing, various medical diagnostics, and so on.
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 (≥1.685dB/%RH) 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.
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