No abstract

Despite the numerous bacteria detection and elimination techniques available nowadays, sensitive diagnosis and treatment of sepsis (caused by the presence of bacteria in the bloodstream), especially at the early stage, remain big challenges. Here we report a nanosystem for early sepsis diagnosis and complete extracorporeal blood disinfection, based on iron oxide magnetic nanoparticles functionalized with chlorin e6 molecules and bacterial species-identifiable aptamers (FeO-Ce6-Apt). We demonstrate that the FeO-Ce6-Apt nanosystem can achieve simultaneous blood bacterial species identification and enrichment in a single step, and the enriched bacteria can be easily detected with the assistance of fluorescence microscopic determination. Based on this FeO-Ce6-Apt nanosystem, successful diagnosis of sepsis caused by a single (Staphylococcus aureus) or multiple species (Staphylococcus aureus and Escherichia coli) of bacteria in mice has been realized. Compared to the gold standard blood culture method, this FeO-Ce6-Apt nanosystem-based strategy has a comparable detection sensitivity (around 10 colony-forming units) but a significantly shortened diagnosis turnaround time (within 1.5 h), revealing its great potential for early sepsis diagnosis in clinical settings. Moreover, benefitting from the strong photodynamic effect of the FeO-Ce6-Apt nanosystem, complete extracorporeal blood disinfection has been achieved. Remarkably, we also demonstrate that the disinfected blood can be reused for mice transfusion application without inducing adverse reactions, indicating the fruitful potential of the FeO-Ce6-Apt nanosystem for sepsis treatment. Apart from the sepsis-associated applications, we believe that the FeO-Ce6-Apt nanosystem could find wide applications in the fields of health and environmental sciences that require bacteria monitoring and sterilization.

A flexible graphene field-effect transistor (Gr-FET) biosensor for ultrasensitive and specific detection of miRNA without labeling and functionalization is reported. The flexible biosensor presents robust performance even after multiple cycles of bending to a cylinder with an 8 mm radius. A DNA probe is designed with partial segment complementary to target miRNA, and immobilized on the graphene surface though π−π stacking interaction. After capture of target miRNA, a Dirac point shift in Gr-FET is induced, which shows a linear relationship with the target miRNA concentration on a semi-log scale. The Gr-FET-based biosensor finishes miRNA detection in 20 min, and is able to achieve a miRNA detection limit as low as 10 fM without any functionalization and labeling. The interaction processes of DNA-graphene and DNA-miRNA are confirmed through surface-enhanced Raman scattering technology. The proposed biosensor will have prospective applications in wearable electronics for health monitoring and disease diagnosis.

The recent outbreak of coronavirus disease 2019 (COVID-19) is highly infectious, which threatens human health and has received increasing attention. So far, there is no specific drug or vaccine for COVID-19. Therefore, it is urgent to establish a rapid and sensitive early diagnosis platform, which is of great significance for physical separation of infected persons after rapid diagnosis. Here, we propose a colorimetric/SERS/fluorescence triple-mode biosensor based on AuNPs for the fast selective detection of viral RNA in 40 minutes. AuNPs with average size of 17 nm were synthesized, and colorimetric, surface enhanced Raman scattering (SERS), and fluorescence signals of sensors are simultaneously detected based on their basic aggregation property and affinity energy to different bio-molecules. The sensor achieves a limit detection of femtomole level in all triple modes, which is 160 fM in absorbance mode, 259 fM in fluorescence mode, and 395 fM in SERS mode. The triple-mode signals of the sensor are verified with each other to make the experimental results more accurate, and the capacity to recognize single-base mismatch in each working mode minimizes the false negative/positive reading of SARS-CoV-2. The proposed sensing platform provides a new way for the fast, sensitive, and selective detection of COVID-19 and other diseases.

The rapid development of two-dimensional (2D) transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties. In particular, palladium diselenide (PdSe2) with a novel pentagonal structure and unique physical characteristics have recently attracted extensive research interest. Consequently, tremendous research progress has been achieved regarding the physics, chemistry, and electronics of PdSe2. Accordingly, in this review, we recapitulate and summarize the most recent research on PdSe2, including its structure, properties, synthesis, and applications. First, a mechanical exfoliation method to obtain PdSe2 nanosheets is introduced, and large-area synthesis strategies are explained with respect to chemical vapor deposition and metal selenization. Next, the electronic and optoelectronic properties of PdSe2 and related heterostructures, such as field-effect transistors, photodetectors, sensors, and thermoelectric devices, are discussed. Subsequently, the integration of systems into infrared image sensors on the basis of PdSe2 van der Waals heterostructures is explored. Finally, future opportunities are highlighted to serve as a general guide for physicists, chemists, materials scientists, and engineers. Therefore, this comprehensive review may shed light on the research conducted by the 2D material community.