An innovative genosensor for the monitoring of Leishmania spp sequence using binding of pDNA to cDNA based on Cit-AgNPs

Advances and Challenges in the Diagnosis of Leishmaniasis

Leishmaniasis remains a significant public health challenge, particularly in endemic regions with limited resources. Traditional diagnostic methods, including microscopy, culture, and serology, though widely utilized, often suffer from limitations such as variable  sensitivity, time delays, and the need for specialized infrastructure. Some of these limitations have been addressed with the emergence of molecular diagnostic techniques. Quantitative PCR (q-PCR), loop-mediated isothermal amplification (LAMP), and recombinase polymerase amplification (RPA) assays have improved  the diagnostic sensitivity and specificity, enabling species identification and detection of asymptomatic infections. Further, nanodiagnostics and portable sequencing technologies such as the MinION™, along with lab-on-chip platforms, are revolutionizing the diagnostic landscape of leishmaniasis by offering point-of-care (POC) options for remote settings and field-based diagnosis. This review provides an in-depth analysis of these cutting-edge advances, discusses their application in resource-constrained settings, and evaluates their potential to reshape the future of leishmaniasis diagnosis and management.

Reliable recognition of DNA methylation using bioanalysis of hybridization on the surface of Ag/GQD nanocomposite stabilized on poly (β-cyclodextrin): A new platform for DNA damage studies using genosensor technology

Due to the role of DNA methylation in causing cancer in the present study, an innovative and inexpensive method was designed for the sensitive detection of DNA methylation. The silver-graphene quantum dots (Ag/GQDs) nano ink with high electrical conductivity was used as a substrate for genosensor fabrication toward identification of DNA hybridization. Also, poly (β-cyclodextrin) (p[β-CD]) has been used as a biointerface for the stabilization of Ag/GQD nano ink. The thiolated pDNA strand (5'-SH-TCCGCTTCCCGACCCGCACTCCGC-3') (as bioreceptor element) was fixed on the substrate and hybridized with methylated (5'-GC(M)GGAGTGC(M)GGGTC(M)GGGAAGC(M)GGA-3') and unmethylated (5'-GCGGAGTGCGGGTCGGGAAGCGGA-3') cDNAs, as target sequences were studied using electroanalysis methods. Under optimal conditions and using electrochemical techniques, the linear range was 1 am to 1 pm with LLOQ of 1aM. Finally, the designed DNA genosensor was used for detection of DNA methylation in human plasma samples and can be used to detect methylation in patient samples. It is expected that the designed DNA-based biodevice will be used to early stage diagnosis of cancer using monitoring of DNA methylation. Also, this type of genosensor can be used for epigenetic studies in the near future.

Identification of DNA methylation by novel optical genosensing: A new platform in epigenetic study using biomedical analysis

Due to the important role of methylation in cancer, the use of sensitive analytical methods for early diagnosis and efficient clinical pharmacotherapy is highly demanded. In this study, an innovative label-free method has been developed for the recognition of methylated DNA in the promoter area of adenomatous polyposis coli gene (APC gene). Also, differentiation of unmethylated DNA (GCGGAGTGCGGGTCGGGAAGCGGA) from methylated cDNA (GC(M)GGAGTGC(M)GGGTC(M)GGGAAGC(M)GGA) was performed using optical synthesized probe (thionine-based polymer). Hybridization of pDNA (TCCGCTTCCCGACCCGCACTCCGC) with various types of cDNA sequences was studied by UV-visible and fluorescence spectroscopy. Also, some of the mismatch sequences {(GC(M)GGAGTAC(M)GGGTC(M)GGGAAGC(M)GGA) and (GCGGAGTACGGGTCGGGAAGCGGA)} were applied as negative control. For this purpose, The synthesized optical probe was characterized by transmission electron microscopy, atomic force microscopy, dynamic light scattering, zeta potential, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, UV-Vis, and fluorescence spectroscopy. Under optimal conditions, the analytical performance of engineered DNA-based assay was studied and exhibited excellent dynamic range (1 zM to 3 pM) with low limit of quantitation (LLOQ) of 1 zM. The designed DNA-based assay showed a high capability of discriminating methylation, unmethylated and mismatched sequences. The engineered genosensor is simple and inexpensive and can detect DNA methylation with high sensitivity. Therefore, the designed geno-assay could detect DNA methylation significantly and discriminate from unmethylated DNA. It is expected that the proposed geno-assay could be used for the detection of DNA methylation, genetic mutations, epigenetic alterations, and early stage diagnosis of various cancer toward efficient clinical pharmacotherapy.

Visual monitoring and optical recognition of digoxin by functionalized AuNPs and triangular AgNPs as efficient optical nano-probes

In this study, we presented elective, sensitive, and rapid UV-Vis spectrophotometry and calorimetric assay for the recognition of digoxin. Therefore, cysteamine-gold nanoparticles (Cys A-AuNPs) in the presence of cysteine acid amine and Silver nanoparticles in the presence of tetramethyl benzidine and hydrogen peroxide (AgNPs-TMB [3,3',5,5'-tetramethylbenzidine]-H₂ O₂ ) were synthesized and utilized as the desired probe. Finally, color variation of probes was observed in the absence and presence of digoxin. Obtained results indicate that the color of Cys A-AuNPs changed from dark pink to light in the absence and the presence of digoxin, respectively. Also, the color of AgNPs-TMB-H₂ O₂ changed from dark blue to light blue, in the absence and the presence of digoxin, respectively. Moreover, UV-Vis spectroscopies results indicate digoxin with a low limit of quantification of 0.125 ppm in human plasma samples which linear range was 0.125 to 11 ppm.

Nanotechnology-aided diagnosis, treatment and prevention of leishmaniasis

Leishmaniasis is a prevalent parasitic infection belonging to neglected tropical diseases. It is caused by Leishmania protozoan parasites transmitted by sandflies and it is responsible for increased morbidity/mortality especially in low- and middle-income countries. The lack of cheap, portable, easy to use diagnostic tools exhibiting high efficiency and specificity impede the early diagnosis of the disease. Furthermore, the typical anti-leishmanial agents are cytotoxic, characterized by low patient compliance and require long-term regimen and usually hospitalization. In addition, due to the intracellular nature of the disease, the existing treatments exhibit low bioavailability resulting in low therapeutic efficacy. The above, combined with the common development of resistance against the anti-leishmanial agents, denote the urgent need for novel therapeutic strategies. Furthermore, the lack of effective prophylactic vaccines hinders the control of the disease. The development of nanoparticle-based biosensors and nanocarrier-aided treatment and vaccination strategies could advance the diagnosis, therapy and prevention of leishmaniasis. The present review intends to highlight the various nanotechnology-based approaches pursued until now to improve the detection of Leishmania species in biological samples, decrease the side effects and increase the efficacy of anti-leishmanial drugs, and induce enhanced immune responses, specifically focusing on the outcome of their preclinical and clinical evaluation.

Utilization of rGO-PEI-supported AgNPs for sensitive recognition of deltamethrin in human plasma samples: A new platform for the biomedical analysis of pesticides in human biofluids

In this study, the rGO-PEI-AgNPs sensor was designed as a new effective platform to sensitive monitoring of deltamethrin in human plasma samples. For this purpose, reduced graphene oxide (rGO)-supported polyethylenimine (PEI) was used as a suitable substrate for dispersion of silver nanoparticles (AgNPs) as amplification and catalytic element. Therefore, a novel interface (rGO-PEI-AgNPs) was prepared by the fully electrochemical method on the surface of glassy carbon electrodes. The engineered nano-sensor showed a wide dynamic range of 10 nM to 1 mM and low limit of quantification (LLOQ) as 10 nM in human plasma sample, which revealed excellent analytical performance for the recognition of deltamethrin with high sensitivity and reproducibility through differential pulse voltammetry and square wave voltammetry techniques. The results confirm that rGO-PEI-AgNPs as a novel biocompatible interface can provide appropriate, reliable, affordable, rapid, and user-friendly diagnostic tools in the detection of deltamethrin in human real samples.