No abstract

Metal–organic frameworks (MOFs) are promising as novel disinfectants due to the reactive oxygen species (ROS) produced in their photocatalytic processes. The optimal MOF is screened as the best disinfectant, representing high-efficacy production of ROS under photocatalytic conditions. However, current methods to screen abundant MOFs for disinfectant application are generally semiquantitative or ex situ methods [such as electron paramagnetic resonance (EPR) measurements], so achieving a strategy that can quantitatively screen an optimal MOF in situ and is reliable is demanded. Herein, we developed a three-dimensional (3D) shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) platform to study the dynamic photocatalytic processes of various MOFs (e.g., ZIF-67, ZIF-8, and UIO-66) in situ. This platform comprises silica shell-isolated gold nanoparticles (AuNPs) modified on silicon nanowire arrays (SiNWArs). The MOF is then self-assembled on the 3D-SHINERS substrate. Using this platform, we recorded dynamic spectroscopic evidence of ROS formation by various MOFs under sunlight irradiation. By dynamic comparison, ZIF-67 has the most robust photocatalytic efficiency, ∼1.7-fold stronger than that of ZIF-8 and ∼42.6-fold stronger than that of UIO-66. As expected, ZIF-67 displays the best antibacterial ability, up to 99% in the agar plate assay. This work provides a versatile platform for dynamically monitoring photocatalytic performance and screening antibacterial MOFs.

Sensitive and reliable clustered regularly interspaced short palindromic repeats (CRISPR) quantification without preamplification of the sample remains a challenge. Herein, we report a CRISPR Cas12a-powered silicon surface-enhanced Raman spectroscopy (SERS) ratiometric chip for sensitive and reliable quantification. As a proof-of-concept application, we select the platelet-derived growth factor-BB (PDGF-BB) as the target. We first develop a microfluidic synthetic strategy to prepare homogeneous silicon SERS substrates, in which uniform silver nanoparticles (AgNPs) are in situ grown on a silicon wafer (AgNPs@ Si) by microfluidic galvanic deposition reactions. Next, one 5′-SH-3′-ROX-labeled single-stranded DNA (ssDNA) is modified on AgNPs via Ag−S bonds. In our design, such ssDNA has two fragments: one fragment hybridizes to its complementary DNA (5′-Cy3-labeled ssDNA) to form double-stranded DNA (dsDNA) and the other fragment labeled with 6′-carboxy-X-rhodmine (ROX) extends out as a substrate for Cas12a. The cleavage of the ROX-tagged fragment by Cas12a is controlled by the presence or not of PDGF-BB. Meanwhile, Cy3 molecules serving as internal standard molecules still stay at the end of the rigid dsDNA, and their signals remain constant. Thereby, the ratio of ROX signal intensity to Cy3 intensity can be employed for the reliable quantification of PDGF-BB concentration. The developed chip features an ultrahigh sensitivity (e.g., the limit of detection is as low as 3.2 pM, approximately 50 times more sensitive than the fluorescence counterpart) and good reproducibility (e.g., the relative standard deviation is less than 5%) in the detection of PDGF-BB.

Herein, we designed and synthesized a novel microRNA (miR)-responsive nanoantenna capable of early diagnosis and smart treatment of acute kidney injury (AKI). The nanoantenna was made of two miniature gold nanorods (AuNRs) (e.g., length: ∼48 nm; width: ∼9 nm) linked together by a rectangular DNA origami nanostructure (rDONs) scaffold (e.g., length: ∼90 nm; width: ∼60 nm) (rDONs@AuNR dimer). The surface plasmon resonance peak of the constructed nanoantenna is located within the NIR-II window (e.g., ∼1060 nm), thus guaranteeing photoacoustic (PA) imaging of the nanoantenna in deep tissues. Intriguingly, the nanoantenna displayed exclusive kidney retention in both healthy mice and ischemia reperfusion-induced AKI mice by leveraging the kidney-targeting ability of rDONs. Distinguished from the stable signals in the healthy mice, the PA signals of the nanoantenna would turn down in the AKI mice due to the AuNR detached from rDONs upon interaction with miR-21, which were up-expressed in AKI mice. The limit of detection toward miR-21 was down to 2.8 nM, enabling diagnosis of AKI as early as 10 min post-treatment with ischemia reperfusion, around 2 orders of magnitude earlier than most established probes. Moreover, the naked rDON scaffold generated by AKI could capture more reactive oxygen species (e.g., 1.5-fold more than rDONs@AuNR dimer), alleviating ischemic AKI. This strategy provided a new avenue for early diagnosis and smart treatment of AKI.

Most existing bioluminescence imaging methods can only visualize the location of engineered bacteria in vivo, generally precluding the imaging of natural bacteria. Herein, we leverage bacteria-specific ATP-binding cassette sugar transporters to internalize luciferase and luciferin by hitchhiking them on the unique carbon source of bacteria. Typically, the synthesized bioluminescent probes are made of glucose polymer (GP), luciferase, Cy5 and ICG-modified silicon nanoparticles and their substrates are made of GP and D-luciferin-modified silicon nanoparticles. Compared with bacteria with mutations in transporters, which hardly internalize the probes in vitro (i.e., ~2% of uptake rate), various bacteria could robustly engulf the probes with a high uptake rate of around 50%. Notably, the developed strategy enables ex vivo bioluminescence imaging of human vitreous containing ten species of pathogens collected from patients with bacterial endophthalmitis. By using this platform, we further differentiate bacterial and non-bacterial nephritis and colitis in mice, while their chemiluminescent counterparts are unable to distinguish them.