Development of a carbon quantum dot-based sensor for the detection of acetylcholinesterase and the organophosphate pesticide

In this study, a proper and reliable fluorometric method is introduced for screening acetylcholinesterase (AChE) and its inhibitors, using carbon quantum dots (CQDs) as the signal reporter. Pure, S-doped, and P-doped CQDs, were synthesized and their recoverable fluorescence quenching properties were observed, when exposed to Hg2+, Cu2+, and Fe3+ quenching ions, respectively. The study on the recovery of their emission showed that after the introduction of another guest substance with a stronger affinity to the quenching ions, their fluorescence is restored. The Design Expert software was employed to compare the performance of the three CQDs, as fluorescent probes, based on their quenching efficiency and the percentage of their emission recovery in the presence of AChE and acetylthiocholine (ATCh). Based on the statistical analysis, among the studied CQDs, S-doped CQD was the most suitable candidate for sensor designing. The detection mechanism for the proposed S-doped CQD-based sensor is as follows: The strong binding of Cu2+ ions to carboxyl groups of S-doped CQD quenches the fluorescence signal. Then, hydrolysis of ATCh into thiocholine (TCh) in the presence of AChE causes fluorescence recovery, due to the stronger affinity of Cu2+ to the TCh, rather than the CQD. Finally, in the presence of malathion and chlorpyrifos inhibitors, AChE loses its ability to hydrolyze ATCh to TCh, so the fluorescence emission remains quenched. Based on the proposed detection technique, the designed sensor showed detection limits of 1.70 ppb and 1.50 ppb for malathion and chlorpyrifos, respectively

Initial study of three different pathogenic microorganisms by gas chromatography-mass spectrometry [version 2; referees: 2 approved, 1 approved with reservations]

Background: Diagnoses  of  respiratory  tract  infections  usually happen  in  the  late  phase  of  the  disease  and  usually  result  in  reduction  of  the  pathogen  load after broad-spectrum  antibiotic  therapy,  but  not  in eradication of the pathogen.  The  development  of a  non-invasive,  fast,  and  accurate  method  to  detect  pathogens  has  always  been  of  interest  to  researchers  and  clinicians  alike.  Previous studies have shown that bacteria produce organic gases.  The  current  study  aimed  to  identify  the  volatile  organic  compounds  (VOCs)  produced  by three  respiratory  tract  pathogens,  including  Staphylococcus  aureus,  Escherichia  coli  and  Candida  albicans. Methods: The  VOCs  produced  were identified by gas chromatography–mass spectrometry (GC-MS), with  prior  collection  of  microbial  volatile  compounds  using  solid  phase  microextraction  (SPME)  fiber.  The volatile compounds were collected by obtaining bacterial headspace samples. Results: Results  showed  that  these  three  organisms  have  various  VOCs,  which  were  analyzed  under  different  conditions.  By ignoring common VOCs, some species-specific VOCs could be detected.  The most important VOC of E. coli was Indole, also some important VOCs produced by S. aureus  were 2,3-Pentandione,  cis-Dihydro-α-terpinyl  acetate,  1-Decyne,  1,3-Heptadiene-3-yne,  2,5-dimethyl  Pyrazine,  Ethyl  butanoate  and  Cyclohexene,4-ethenyl  furthermore,  most  of  identified  compounds  by  C.  albicans are  alcohols. Conclusions: The  detection  of  VOCs  produced  by  infectious  agents  maybe  the  key  to  make   a  rapid  and  precise  diagnosis  of  infection,  but  more  comprehensive  studies  must  be  conducted  in this  regard

Initial study of three different pathogenic microorganisms by gas chromatography-mass spectrometry [version 3; referees: 2 approved, 1 approved with reservations]

Background: Diagnoses  of  respiratory  tract  infections  usually happen  in  the  late  phase  of  the  disease  and  usually  result  in  reduction  of  the  pathogen  load after broad-spectrum  antibiotic  therapy,  but  not  in eradication of the pathogen.  The  development  of a  non-invasive,  fast,  and  accurate  method  to  detect  pathogens  has  always  been  of  interest  to  researchers  and  clinicians  alike.  Previous studies have shown that bacteria produce organic gases.  The  current  study  aimed  to  identify  the  volatile  organic  compounds  (VOCs)  produced  by three  respiratory  tract  pathogens,  including  Staphylococcus  aureus,  Escherichia  coli  and  Candida  albicans. Methods: The  VOCs  produced  were identified by gas chromatography–mass spectrometry (GC-MS), with  prior  collection  of  microbial  volatile  compounds  using  solid  phase  microextraction  (SPME)  fiber.  The volatile compounds were collected by obtaining bacterial headspace samples. Results: Results  showed  that  these  three  organisms  have  various  VOCs,  which  were  analyzed  under  different  conditions.  By ignoring common VOCs, some species-specific VOCs could be detected.  The most important VOC of E. coli was indole, also some important VOCs produced by S. aureus  were 2,3-pentandione,  cis-dihydro-α-terpinyl  acetate,  1-decyne,  1,3-heptadiene,  2,5-dimethyl  pyrazine,  ethyl  butanoate  and  cyclohexene,4-ethenyl. Furthermore,  most  of the identified  compounds  by  C.  albicans are  alcohols. Conclusions: The  detection  of  VOCs  produced  by  infectious  agents  maybe  the  key  to  make   a  rapid  and  precise  diagnosis  of  infection,  but  more  comprehensive  studies  must  be  conducted  in this  regard

Synergistic chemo-photothermal therapy using gold nanorods supported on thiol-functionalized mesoporous silica for lung cancer treatment

Abstract Cancer therapy necessitates the development of novel and effective treatment modalities to combat the complexity of this disease. In this project, we propose a synergistic approach by combining chemo-photothermal treatment using gold nanorods (AuNRs) supported on thiol-functionalized mesoporous silica, offering a promising solution for enhanced lung cancer therapy. To begin, mesoporous MCM-41 was synthesized using a surfactant-templated sol–gel method, chosen for its desirable porous structure, excellent biocompatibility, and non-toxic properties. Further, thiol-functionalized MCM-41 was achieved through a simple grafting process, enabling the subsequent synthesis of AuNRs supported on thiol-functionalized MCM-41 (AuNR@S-MCM-41) via a gold-thiol interaction. The nanocomposite was then loaded with the anticancer drug doxorubicin (DOX), resulting in AuNR@S-MCM-41-DOX. Remarkably, the nanocomposite exhibited pH/NIR dual-responsive drug release behaviors, facilitating targeted drug delivery. In addition, it demonstrated exceptional biocompatibility and efficient internalization into A549 lung cancer cells. Notably, the combined photothermal-chemo therapy by AuNR@S-MCM-41-DOX exhibited superior efficacy in killing cancer cells compared to single chemo- or photothermal therapies. This study showcases the potential of the AuNR@S-MCM-41-DOX nanocomposite as a promising candidate for combined chemo-photothermal therapy in lung cancer treatment. The innovative integration of gold nanorods, thiol-functionalized mesoporous silica, and pH/NIR dual-responsive drug release provides a comprehensive and effective therapeutic approach for improved outcomes in lung cancer therapy. Future advancements based on this strategy hold promise for addressing the challenges posed by cancer and transforming patient care