Biological Diagnosis Research Articles

Fluorescence DNA Switch for Highly Sensitive Detection of miRNA Amplified by Duplex-Specific Nuclease.

DNA is a type of promising material for the construction of sensors owing to its sequence programmability to control the formation of certain structures. MicroRNA (miRNA) can be applied as promising biomarkers for the diagnosis of a range of diseases. Herein, a novel fluorescent sensing strategy for miRNA is proposed combining duplex-specific nuclease (DSN)-mediated amplification and dumbbell DNA structural switch. Gold nanoparticles (AuNPs) are employed, which provide a 3D reaction interface. They also act as effective fluorescence quenchers. The proposed sensor exhibits high sensitivity (sub-femtomolar level) with a wide dynamic range. In addition, excellent selectivity to distinguish homology sequences is achieved. It also performs satisfactorily in biological samples. Overall, this fluorescent sensor provides a powerful tool for the analysis of miRNA levels and can be applied for related biological studies and clinical diagnosis.

Self-assembled 1D nanostructures for direct nanoscale detection and biosensing

•Self-assembled 1D nanostructures allow for nanoscale detection and visualization •Enabled direct measurement of nanoscale objects at the single-particle level •Suitable for rapid and ultrasensitive sensing of virus samples, including SARS-CoV-2 Directly accurate detection of nanoscale objects remains a great challenge to many fields, including self-assembly, nanoparticle engineering, nanomaterial characterization, and biological diagnosis. Here, we report a general method for visualizable detection and measurement of many nanoscale objects by using one-dimensional (1D) nanostructures, including nanoparticles, defects, and pathogens. The large-scale 1D nanostructures are robustly prepared through the template-assisted self-assembly of colloidal nanoparticles, which exhibit wide spectral tunability in the visible region. In addition to the scalability, they can significantly amplify the weak optical signals from nanoscale objects, pushing the detection sensitivity down to the single-particle level. Then, we achieve the rapid and ultrasensitive testing of different clinical virus samples by using a simple optical microscope or a portable cell phone. This work demonstrates a label-free, simple, and high-efficiency optical detection platform at the nanoscale, which has a broad range of applications from material synthesis to in vitro diagnosis. Directly accurate detection of nanoscale objects remains a great challenge to many fields, including self-assembly, nanoparticle engineering, nanomaterial characterization, and biological diagnosis. Here, we report a general method for visualizable detection and measurement of many nanoscale objects by using one-dimensional (1D) nanostructures, including nanoparticles, defects, and pathogens. The large-scale 1D nanostructures are robustly prepared through the template-assisted self-assembly of colloidal nanoparticles, which exhibit wide spectral tunability in the visible region. In addition to the scalability, they can significantly amplify the weak optical signals from nanoscale objects, pushing the detection sensitivity down to the single-particle level. Then, we achieve the rapid and ultrasensitive testing of different clinical virus samples by using a simple optical microscope or a portable cell phone. This work demonstrates a label-free, simple, and high-efficiency optical detection platform at the nanoscale, which has a broad range of applications from material synthesis to in vitro diagnosis.

Abundant microbial communities act as more sensitive bio-indicators for ecological evaluation of copper mine contamination than rare taxa in river sediments

Bacterial and fungal communities have been widely applied as bio-indicators for ecological evaluation of copper (Cu) mine pollution in river sediments. However, the response pattern of their abundant and rare sub-communities is still unknown, limiting the further development of biological diagnostics. Here, the alpha-diversity, community composition, environmental contribution and co-occurrence network of total, abundant and rare taxa for bacteria and fungi in the Jiaopingdu Cu Mine wastewater treatment plant (WWTP) were investigated through high-throughput sequencing. The results revealed different responses of microbial alpha-diversity for abundant and rare sub-communities. The abundant taxa were ubiquitous in all sediments, while rare taxa exhibited increases of species richness in polluted areas because of heterochthonous inputs of WWTP drainage. Nevertheless, the variations of community composition were consistent for bacterial and fungal abundant and rare taxa, all of which showed significant dissimilarity between control and polluted areas. Distance-decay relationship and canonical correlation analysis indicated that abundant taxa assemblies (rbacteria = −0.924, rfungi = −0.684) were more strongly driven by environmental changes than rare ones (rbacteria = −0.626, rfungi = −0.349), because abundant microbes had higher proportions of significant variations in abundance. Co-occurrence networks revealed more keystone species with high node degree and centrality among abundant taxa compared with rare ones. Moreover, bacterial abundant and rare taxa were more sensitive to Cu mine pollution than relevant fungal taxa owing to different Cu tolerance. In conclusion, among all microbial sub-communities, abundant bacteria had the highest environmental sensitivity, suggesting their important application in biological diagnosis of Cu mine pollution. Accordingly, the abundant taxa could act as “key reservoir” for future selection of specific indicator species, for example Thiobacillus, while rare taxa no longer need excessive in-depth analysis, which would greatly improve microbial diagnosis efficiency.

Applications of DNA bases, Graphene and Biosensors : A Critical Review

The current research paper presents a theoretical exploration of the interaction between 2-D nanomaterials and the DNA bases that embody graphene properties and biosensors applications. Regarding its role as a conveyer of genetic information, Deoxyribonucleic acid (DNA) has been understood as a constructed substance for various components and structural collations with nanoparticle merits. It is counted as the bearer of genetic information in the human being's life, where it is a fundamental biomacromolecule in almost all living apparatuses. Because of DNA's self-recognition characteristics (based on the specific base pairing of G-C and T-A), more attention has been drawn to monolayer films of nucleic acids. It is seen that many doping techniques have been carefully investigated. Thus, this survey article provides a new and comprehensive outline of the modern strategies that include specifically immobilized DNA on Graphene. further, it is expected in the near future that there will be a designee of DNA nanodevices that are distinguished in smartness, accuracy, and sensitivity where they will contribute to the fields of biological analysis, clinical diagnosis, and biomedicine

Single-Molecule Biosensing of Alkaline Phosphatase in Cells and Serum Based on Dephosphorylation-Triggered Catalytic Assembly and Disassembly of the Fluorescent DNA Chain.

Alkaline phosphatase (ALP) is a valuable biomarker and effective therapeutic target for the diagnosis and treatment of diverse human diseases, including bone disorder, cardiovascular disease, and cancers. The reported ALP assays often suffer from laborious procedures, costly reagents, inadequate sensitivity, and large sample consumption. Herein, we report a new single-molecule fluorescent biosensor for the simple and ultrasensitive detection of ALP. In this assay, the ALP-catalyzed dephosphorylation of detection probe can protect the detection probe against lambda exonuclease-mediated digestion, and the remaining detection probes can trigger ceaseless hybridization between two Cy5-labeled hairpin probes through toehold-mediated DNA strand displacement, generating a long fluorescent DNA chain, which can be subsequently separated from unhybridized hairpin probes and disassembled into dispersed Cy5 moieties upon NaOH treatment. The free Cy5 moieties indicate the presence of ALP and can be directly quantified via single-molecule counting. This biosensor enables efficient amplification and transduction of the target ALP signal through enzyme-free assembly and disassembly processes, significantly simplifying the experimental procedure and improving the assay accuracy. The proposed biosensor allows specific and ultrasensitive detection of ALP activity with a detection limit down to 2.61 × 10-6 U mL-1 and is suitable for ALP inhibition assay and kinetic analysis. Moreover, this biosensor can be applied for endogenous ALP detection in human cells and clinical human serum, holding the potential in the ALP biological function study and clinical diagnosis.

Recent advances in bioprobes and biolabels based on cyanine dyes.

As a functional dye, cyanine dye promotes the widespread application of bioprobes in the fields of medicine, genetics and environment, owing to its advantages of good photophysical properties, excellent biocompatibility and low toxicity to biological systems. Nowadays, it is mainly used in the fields of life sciences such as fluorescent labeling of biological macromolecules, disease diagnosis, immunoassay and DNA detection, all of which lie at the core of this review. First, we briefly introduced the characteristics and principles of the cyanine dye bioprobe. Afterward, we paid attention to the recent progress of cyanine dye bioprobes widely used in the 10years from 2010 to 2020. The application of cyanine dyes as bioprobes with different identification elements, including enzymes, organelles, immunity and DNAs, was mainly summarized. Finally, this review gave an outlook on the future development trend of cyanine dye bioprobes. This facilitates the construction of a new type of multifunctional fluorescent probe and promotes its clinical application.

Solution processed low power organic field-effect transistor bio-chemical sensor of high transconductance efficiency

Developing organic field-effect transistor (OFET) biosensors for customizable detection of biomarkers for many diseases would provide a low-cost and convenient tool for both biological studies and clinical diagnosis. In this work, design principles of the OFET transducer for biosensors were derived to relate the signal-to-noise ratio (SNR) to the device-performance parameters. Steep subthreshold swing (SS), proper threshold voltage (Vth), good-enough bias-stress stability, and mechanical durability are shown to be the key prerequisites for realizing OFET bio-sensors of high transconductance efficiency (gm/ID) for large SNR. Combining a low trap-density channel and a high-k/low-k gate dielectric layer, low-temperature (<100 °C) solution-processed flexible OFETs can meet the performance requirements to maximize the gm/ID. An extended gate-structure OFET biosensor was further implemented for label-free detection of miR-21, achieving a detection limit below 10 pM with high selectivity at a low operation voltage (<1 V).

A Novel Ratiometric Electrochemical Biosensor Using Only One Signal Tag for Highly Reliable and Ultrasensitive Detection of miRNA-21.

Herein, a novel ratiometric electrochemical biosensor with methylene blue (MB) as the only one signal tag was proposed for highly reliable and ultrasensitive detection of microRNA-21 (miRNA-21) under the assistance of an intelligent target-induced dual signal amplification (T-DSA). First, a small amount of target miRNA-21 could produce abundant mimic targets DNA S1 and Zn2+ through target-induced recycle and acid dissolution, respectively. Then, S1 triggered rolling circle amplification (RCA) to generate functional DNA nanospheres (DSP) encoded by DNAzyme and substrate sequence for loading numerous signal tag MB with a remarkable electrochemical signal (signal on), and the Zn2+ cofactor mediated the nonviolent DNAzyme-catalyzed cleavage of DSP to sharply release MB with obviously reduced electrochemical responses (signal off). Impressively, our strategy could controllably load and release the only signal tag MB through the well-designed DSP to effectively avoid the false positive responses caused by the non-ideal upright state of DNA probes connected to electrodes in traditional distance-dependent signal adjustment ratiometric strategies with two different signal tags. Meanwhile, with the aid of innovative T-DSA recycle and RCA-produced functional DSP, the detection sensitivity of this sensing platform was significantly improved. As a result, the proposed biosensor successfully realized highly reliable and ultrasensitive detection of miRNA-21 with a detection limit down to 26.7 aM, which shows exceptional promise in biological analysis and medical diagnosis.

Identifying Potential New Gene Expression-Based Biomarkers in the Peripheral Blood Mononuclear Cells of Hepatitis B-Related Hepatocellular Carcinoma.

Objective The analysis of the gene expression of peripheral blood mononuclear cells (PBMCs) is important to clarify the pathogenesis of hepatocellular carcinoma (HCC) and the detection of suitable biomarkers. The purpose of this investigation was to use RNA-sequencing to screen the appropriate differentially expressed genes (DEGs) in the PBMCs for the HCC. Methods The comprehensive transcriptome of extracted RNA of PBMC (n = 20) from patients with chronic hepatitis B (CHB), liver cirrhosis, and early stage of HCC (5 samples per group) was carried out using RNA-sequencing. All raw RNA-sequencing data analyses were performed using conventional RNA-sequencing analysis tools. Next, gene ontology (GO) analyses were carried out to elucidate the biological processes of DEGs. Finally, relative transcript abundance of selected DEGs was verified using qRT-PCR on additional validation groups. Results Specifically, 13, 1262, and 1450 DEGs were identified for CHB, liver cirrhosis, and HCC, when compared with the healthy controls. GO enrichment analysis indicated that HCC is closely related to the immune response. Seven DEGs (TYMP, TYROBP, CD14, TGFBI, LILRA2, GNLY, and GZMB) were common to HCC, cirrhosis, and CHB when compared to healthy controls. The data revealed that the expressions of these 7 DEGs were consistent with those from the RNA-sequencing results. Also, the expressions of 7 representative genes that had higher sensitivity were obtained by receiver operating characteristic analysis, which indicated their important diagnostic accuracy for HBV-HCC. Conclusion This study provides us with new horizons into the biological process and potential prospective clinical diagnosis and prognosis of HCC in the near future.

Functionalization of Rhodamine Platforms with 3-Hydroxy-4-pyridinone Chelating Units and Its Fluorescence Behavior towards Fe(III).

Functionalization of xanthene fluorophores with specific receptor units is an important topic of research aiming for the development of new analytical tools for biological sciences, clinical diagnosis, food and environmental monitoring. Herein, we report a new dihydrorosamine containing two active amino groups, which was functionalized with 3-benzyloxy-1-(3′-carboxypropyl)-2-methyl-4-pyridinone through an amide coupling strategy. Benzylated mono- and di-functionalized dihydrorosamine derivatives (H in position 9 of the xanthene) were obtained, but with modest reaction yields, requiring long and laborious purification procedures. Looking for a more efficient approach, rhodamine 110 was selected to react with the carboxypropyl pyridinone, enabling the isolation of the corresponding mono- and di-functionalized derivatives in amounts that depend on the excess of pyridinone added to the reaction. The structure of all compounds was established by 1H and 13C NMR, MS (ESI) and their absorption and emission properties were evaluated in dichloromethane. The fluorescence behavior of the debenzylated mono-rhodamine 110 derivative in the presence of Fe(III) was studied, making it an interesting fluorogenic dye for future optical sensing applications.

Chemiluminescent Probes Based on 1,2-Dioxetane Structures For Bioimaging.

Chemiluminescent probes based on 1,2-dioxetane scaffold are one of the most sensitive imaging modalities for detecting disease-related biomarkers and can obtain more accurate biological information in cells and in vivo. Due to the elimination of external light excitation, the background autofluorescence problem in fluorescence technology can be effectively avoided, providing ultrahigh sensitivity and signal-to-noise ratio for various applications. In this review, we highlight a comprehensive but concise overview of activatable 1,2-dioxetane-based chemiluminescent probes by reporting significant advances in accurate detection and bioimaging. The design principles and applications for reactive species, enzymes, and other disease-related biomarkers are systematically discussed and summarized. The challenges and potential prospects of chemiluminescent probes are also discussed to further promote the development of new chemiluminescence methods for biological analysis and diagnosis.

Dengue virus circulation in West Africa: An emerging public health issue

Dengue is the most widespread arbovirosis in the world, with approximately 390 million cases per year, 96 millions of which have clinical manifestations and 25,000 deaths. In West Africa, the circulation of this virus in human populations was first reported in the 1960s in Nigeria. Clinical diagnosis of dengue in West Africa is made difficult by the existence of other diseases with similar clinical presentations. Biological diagnosis remains therefore the only alternative. This biological diagnosis requires high quality equipment and well-trained personnel, which are not always available in resource-limited countries. Thus, many cases of dengue fever are consistently reported as malaria, leading to mismanagement, which can have serious consequences on the health status of patients. It is therefore necessary to set up surveillance systems for febrile infections of unknown origin in Africa by strengthening the diagnostic capacities of national laboratories.

Computer-Based Activity to Engage Students in Exploring Biodiversity Decline &amp; Extinction

Understanding the main causes of biodiversity decline is an essential part of the syllabus of any university-level course in conservation biology. A novel computer-based activity is described for introducing students to using the International Union for Conservation of Nature (IUCN) Red List database. The specific objectives of this activity are (1) to understand the main causes that threaten species worldwide and, if these causes differ, to try to elucidate the underlying processes that might be responsible for these differences in a given country and (2) to train students how to use digital biological data platforms, such as the IUCN Red List, and how to analyze and interpret biological data. To achieve these goals, students must obtain information from the IUCN Red List to assess why species are threatened globally and in a given country. Based on the total number of threatened species, students calculate the percentage of species affected by each threat within each Red List category and for all categories combined both globally and at the national level. The activity ends with a discussion in the classroom where the students are expected to share their interpretations about the main causes that threaten biodiversity at different scales of analysis and the applications of their findings in a conservation context. The activity is expected to increase the awareness of students regarding environmental issues and to develop different key competencies and basic skills as learning outcomes, including expertise in biological diagnosis, information management, and using the internet as an information source.

Rôle du biologiste dans le traitement des dermatophyties : conseils thérapeutiques et prophylactiques

AbstractDermatophytosis represent a frequent reason for consultation in dermatology. Their treatment involve active antifungal molecules active on dermatophyte species, mainly using a systemic route. The choice of the treatment varies with the location of the infection, the number of attacks and the extent of the lesions. Terbinafine is the molecule of choice with either topical and systemic formulation. Terbinafine is the pivotal drug in particular for the treatment of onychomycosis, extensive skin dermatophytosis and more recently for tinea capitis in children, as griseofulvin is no longer marketed in France. The medical microbiologist, who has a predominant role in the biological diagnosis, must provide the prescribing physician, but also the patient, or even his entourage, with all useful informations regarding the origin of the contamination, the monitoring of the treatment and the prevention of relapses.

Cholesterol metabolic pattern is changed between hepatocellular carcinoma with wild-type and mutated β-catenin.

Background: The WNT/β-catenin signaling pathway is a highly conserved and vital molecular mechanism that regulates cell development, cellular proliferation, and differentiation. Hepatocellular carcinoma (HCC) is a kind of tumor with frequent aberrant activation of β-catenin pathway signaling. Different statuses and locations of β-catenin affected the biological behavior, diagnosis, and treatment of HCC. It has been proved the mutation level of CTNNB1 is relevant to the effect of immunotherapy of HCC.

Diagnostic biologique des dermatophytoses

AbstractDermatophytoses are very common causes of consultation in dermatology. The diagnosis of these superficial infections, affecting the skin, nails and hair, is usually not clinically obvious and requires mycological analysis, especially for infections of the scalp and nails. Direct microscopic examination of clinical samples using clearing agents provides a quick response and should be combined with cultures on specific media. Histological analysis, which is considered the gold standard for the diagnosis of onychomycosis, is seldom performed and as direct examination, allows only visualisation of fungal elements without precise identification of the fungi. Accurate identification of the causative agent is necessary to initiate an appropriate treatment but also for setting prophylactic measures. However, conventional methods often lack sensitivity and species identification from cultures may require up to four weeks. Thus, the use of fluorochromes may greatly enhance the sensitivity of direct examination, as the use of culture media containing antifungal deactivators may enhance the sensitivity of cultures. Finally, despite the commercial availability of PCR-based kits, the biological diagnosis of dermatophytosis still relies on standard mycological procedures (direct examination and specific cultures), which remain the most informative and the least expensive procedures.

Bacterial Cellulose-A Remarkable Polymer as a Source for Biomaterials Tailoring.

Nowadays, the development of new eco-friendly and biocompatible materials using ‘green’ technologies represents a significant challenge for the biomedical and pharmaceutical fields to reduce the destructive actions of scientific research on the human body and the environment. Thus, bacterial cellulose (BC) has a central place among these novel tailored biomaterials. BC is a non-pathogenic bacteria-produced polysaccharide with a 3D nanofibrous structure, chemically identical to plant cellulose, but exhibiting greater purity and crystallinity. Bacterial cellulose possesses excellent physicochemical and mechanical properties, adequate capacity to absorb a large quantity of water, non-toxicity, chemical inertness, biocompatibility, biodegradability, proper capacity to form films and to stabilize emulsions, high porosity, and a large surface area. Due to its suitable characteristics, this ecological material can combine with multiple polymers and diverse bioactive agents to develop new materials and composites. Bacterial cellulose alone, and with its mixtures, exhibits numerous applications, including in the food and electronic industries and in the biotechnological and biomedical areas (such as in wound dressing, tissue engineering, dental implants, drug delivery systems, and cell culture). This review presents an overview of the main properties and uses of bacterial cellulose and the latest promising future applications, such as in biological diagnosis, biosensors, personalized regenerative medicine, and nerve and ocular tissue engineering.

Epidemiological, clinical and therapeutic aspects of chronic lymphoid hemopathies observed at the National Reference University Hospital Center (CHU-RN) of N Djamena

Aim. This study aimed to determine the epidemiological, clinical, therapeutic profile of chronic lymphoid hemopathies (CLH) and the viral factors linked to the genesis of HLCs at the CHU-RN of Ndjamena in Chad. Methods. A descriptive cross-sectional study over two and a half years, from October 2017 to March 2020 at the Hematology Unit of the National Reference University Hospital Center (CHU-RN) of Ndjamena. Were included patients in whom the diagnosis of chronic lymphoid hemopathy had been made. Results. Ninety-eight (98) cases of hematological malignancies were recorded out of 531 hematological consultations including 66 (12.43%) CLH and 67.35% of hematological malignancies with an annual incidence of 26.4 cases. Chronic lymphocytic leukemia (CLL) was 56.06% (n=37) followed by 25.76% (n=17) Malignant non-Hodgkin's lymphoma, 15.15% (n=10) Hodgkin's lymphoma and 3.03 % (n=2) cutaneous lymphoma. A male predominance was observed for all types of CLH. The most represented age groups were those of 51 to 60 years for CLL and 11 to 20 years for lymphomas. Conclusion: This study made it possible to have a better epidemiological knowledge and the viral factors related to the genesis of CLH at the CHU-RN of Ndjamena. It revealed difficulties in biological diagnosis and management, in particular the initiation of chemotherapy.

Sensitivity Improvement of Surface Plasmon Resonance Biosensors with GeS-Metal Layers

Surface plasmon resonance (SPR) biosensors, with germanium sulfide (GeS) as a sensitive medium and Al/Ag/Au as the metal layers, are reported as we aim to improve the sensitivities of the biosensors. The sensitivities in conventional SPR biosensors, consisting of only metal Al, Ag, and Au layers, are 111°/RIU, 117°/RIU, 139°/RIU, respectively. Additionally, these sensitivities of the SPR biosensors based on the GeS-Al, GeS-Ag, and GeS-Au layers have an obvious improvement, resultant of 320°/RIU, 295°/RIU, and 260°/RIU, respectively. We also discuss the changing sensing medium GeS thickness using layer number to describe the scenario which brought about the diversification on the figure of merit (FOM) and optical absorption (OA) performance of the biosensors. These biosensors show obvious improvement of sensitivity and have strong SPR excitation to analytes; we believe that these kind biosensors could find potential applications in biological detection, chemical examination, and medical diagnosis.

Surface Functionalization, Bioanalysis, and Applications: Progress of New Magnetoelastic Biosensors

Magnetoelastic (ME) biosensors are portable, nontoxic, inexpensive, compatible with wireless networks, and have high sensitivity, accuracy, and specificity toward the target element. Thus, they have attracted considerable attention in application of biological identification, chemical detection, and medical diagnosis, as well as in many academic achievements in the field of sensor research. Herein, the recent progress of ME biosensors, including surface functionalization, bioanalysis, and its applications is critically reviewed. The remaining scientific and technological challenges related to the development of novel ME biosensors with new materials and structures in this field are elaborated, too. This review not only can provide a guideline for researchers in future development of ME biosensors, but also further improves their detection performance and expand the scope of their applications.