A novel ratiometric fluorescent probe based on dual-emission carbon dots for highly sensitive detection of salicylic acid.

In this study, a novel ratiometric fluorescence probe based on dual-emission carbon dots (CDs) for the sensitive detection of salicylic acid (SA) was constructed for the first time. The dual-emission CDs were synthesized by simple hydrothermal method using tartaric acid (TA) and m-phenylenediamine (mPD) as raw materials. In the presence of SA, the fluorescence intensity of CDs was enhanced at 499 nm, but remained basically unchanged at 439 nm. This phenomenon is caused by the intermolecular hydrogen bond interactions. The concentrations of SA had an excellent linear relationship with CDs' fluorescence intensity ratio (F499/F439) in a range of 1 âˆ¼ 120 and 120 âˆ¼ 240 µM with low detection limits of 0.68 and 1.05 µM. The established ratiometric fluorescent probe is economical, simple and green, and can be used for the effective detection of SA. In addition, the proposed ratiometric fluorescent probe was successfully used to monitor SA in facial mask and toning lotion samples with a satisfactory recovery of 99.7-106.7 %. The results show that the constructed fluorescent probe based on dual-emission CDs has a great potential for the rapid and sensitive analysis of SA in actual samples.

In vitro susceptibility profiles of Candida parapsilosis species complex subtypes from deep infections to nine antifungal drugs.

Introduction. The Candida parapsilosis complex can be divided into C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis subtypes. It is uncommon for drug sensitivity tests to type them.Gap Statement. In routine susceptibility reports, drug susceptibility of C. parapsilosis complex subtypes is lacking.Aim. The aim of this study is to investigate the antifungal susceptibility and clinical distribution characteristics of the C. parapsilosis complex subtypes causing deep infection in patients.Methodology. Non-repetitive strains of C. parapsilosis complex isolated from deep infection from 2017 to 2019 were collected. Species-level identification was performed using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer and confirmed using ITS gene sequencing, when necessary. Antifungal susceptibility testing was performed using the Sensititre YeastOne system method.Results. A total of 244 cases were included in the study, including 176 males (72.13 %, 60.69±13.43 years) and 68 females (27.87 %, 60.21±10.59 years). The primary diseases were cancer (43.44 %), cardiovascular disease (25.00 %), digestive system diseases, (18.44 %), infection (6.97 %), and nephropathy (6.15 %). Strains were isolated from the bloodstream (63.11 %), central venous catheters (15.16 %), pus (6.56 %), ascites (5.74 %), sterile body fluid (5.33 %), and bronchoalveolar lavage fluid (BALF, 4.09 %). Of the 244 C. parapsilosis complex strains, 179 (73.26 %) were identified as C. parapsilosis sensu stricto, 62 (25.41 %) were C. orthopsilosis, and three (1.23 %) were C. metapsilosis. Only one C. parapsilosis sensu stricto strain was resistant to anidulafungin, micafungin, caspofungin, and voriconazole, and it was non-wild-type (NWT) to amphotericin B. Furthermore, six C. parapsilosis sensu stricto strains were resistant to fluconazole, and one was dose-dependent susceptible. Five C. parapsilosis sensu stricto strains were NWT to posaconazole. Only one C. orthopsilosis strain was NWT for anidulafungin, micafungin, caspofungin, fluconazole, voriconazole, amphotericin B, and posaconazole, while the rest of the strains were wild-type.Conclusion. C. parapsilosis sensu stricto was the main clinical isolate from the C. parapsilosis complex in our hospital. Most strains were isolated from the bloodstream. The susceptibility rate to commonly used antifungal drugs was more than 96 %. Furthermore, most of the infected patients were elderly male cancer patients.