Lysosome-targetable brightly green fluorescence carbon dots for real-time monitoring in cell and highly efficient removal in environment of hypochlorite

Synthesis of non-modified near-infrared carbon dots for hypochlorite detection and cell membrane imaging

Devising carbon dots with long wavelength emission (red light or near infrared), high selectivity and good bio-compatibility is critical in fluorescence detection and imaging, but achieving this goal remains a great challenge. Herein, near-infrared emissive carbon dots (NIR-CDs) with obvious emission characteristic of 653 nm were synthesized through hydrothermally treatment of toluidine bule and gallic acid. Noticeably, the NIR-CDs exhibited excellent selectivity and sensitivity to hypochlorite (ClO-), and the limit of detection is as low as 42.7 nM. The selective recognition reaction between ClO- and the surface functional groups of NIR-CDs inhibits the fluorescence from NIR-CDs. The quenching mechanism was confirmed by fluorescence lifetime decays, FT-IR spectroscopy and UV-vis absorption spectra. More remarkably, the NIR-CDs have rich hydrophilic groups showed lower cytotoxicity, excellent bio-compatibility and specific cell membrane localization ability. The established spectrofluorometric method based on NIR-CDs has been used to determination of ClO- level in tap water sample, the recoveries were 97.7 %-103.3 %. In addition, the NIR-CDs also has been successfully applied for the imaging of cell membrane. The study provides a novel idea for developing NIR ClO- probe as well as cell membrane localization probe based on CDs, which present bright prospects in real water samples monitoring and cell membrane imaging.

One-Pot Three Carbon Dots with Various Lifetimes Rooted in Different Decarboxylation Degrees for Matrix-Free, Anti-Oxygen, and Time-Resolved Information Encryption and Cellular Imaging

Activating long-lived room temperature phosphorescence (RTP) in the aqueous environment and thus realizing matrix-free, anti-oxygen, and time-resolved information encryption and cellular imaging remain a great challenge. Here, we fabricated three types of carbon dots (C-dots), i.e., fluorescent C-dots (F-C-dots) and two types of phosphorescent C-dots denoted as Pw-C-dots and Py-C-dots by a one-pot strategy. Their formation was attributed to the difference in the decarboxylation degree at high temperatures using trimesic acid (TMA) as a sole precursor. Unexpectedly, the yield reached as high as ∼92%, and the proportions were ∼27% for F-C-dots, ∼17% for Pw-C-dots, and ∼56% for Py-C-dots. These nanomaterials could help implement carbon peaking and carbon neutrality. Both green RTP of the two C-dots resulted from the small energy gap (ΔEST). These two RTP C-dots had a long lifetime of over 270 ms with a relatively high quantum yield (4.5 and 6.2%). They exhibited excellent photostability and anti-photobleaching performances. The dry and wet powders of the RTP C-dots were applied to high-level information encryption. The lifelike patterns were greatly different from those of the original ones and could last for several seconds to the naked eye, demonstrating that the RTP C-dots could be potentially employed as anti-oxygen and time-resolved contrast reagents. Most significantly, the cellular imaging experiments showed that the biofriendly PVP-coated Py-C-dots could localize at lysosomes and sustain hundreds of milliseconds. This approach not only pioneers a time-resolved lysosome localization model but also opens up a promising door for anti-oxygen and time-resolved RTP cytoimaging.

Development of stimuli-responsive lyotropic liquid crystalline nanoparticles targeting lysosomes: Physicochemical, morphological and drug release studies

The abilities of sub-cellular targeting and stimuli-responsiveness are critical challenges in pharmaceutical nanotechnology. In the present study, glyceryl monooleate (GMO)-based non-lamellar lyotropic liquid crystalline nanoparticles were stabilized by the poly(2-(dimethylamino)ethyl methacrylate)-b-poly(lauryl methacrylate) block copolymer carrying tri-phenyl-phosphine cations (TPP-QPDMAEMA-b-PLMA), either used alone or in combination with other polymers as co-stabilizers. The systems were designed to perform simultaneously sub-cellular targeting, stimuli-responsiveness and to exhibit stealthiness. The physicochemical characteristics and fractal dimensions of the resultant nanosystems were obtained from light scattering techniques, while their micropolarity and microfluidity from fluorescence spectroscopy. Their morphology was assessed by cryo-TEM, while their thermal behavior by microcalorimetry and high-resolution ultrasound spectroscopy. The analyzed properties, including the responsiveness to pH and temperature, were found to be dependent on the combination of the polymeric stabilizers. The subcellular localization was monitored by confocal microscopy, revealing targeting to lysosomes. Subsequently, resveratrol was loaded into the nanosystems, the entrapment efficiency was investigated and in vitro release studies were carried out at different conditions, in which a stimuli-triggered drug release profile was achieved. In conclusion, the proposed multi-functional nanosystems can be considered as potentially stealth, stimuli-responsive drug delivery nanocarriers, with targeting ability to lysosomes and presenting a stimuli-triggered drug release profile.