Immediate postinterventional flat-panel CT: Differentiation of hemorrhagic transformation from contrast exudation of acute ischemic stroke patients after thrombectomy.

BACKGROUND: Flat-panel computed tomography (CT) is an available imaging modality immediately after endovascular thrombectomy without transferring patients to the CT room. PURPOSE: To determine the accuracy of flat-panel CT scans in differentiating hemorrhagic transformation (HT) from contrast exudation after thrombectomy in patients with acute ischemic stroke (AIS). MATERIAL AND METHODS: From January 2019 to December 2021, consecutive patients with AIS who received an immediate flat-panel CT scan and follow-up neuroimaging after thrombectomy were enrolled in our study. The receiver operating characteristic curve was adopted to assess the discriminating accuracy of characteristics of flat-panel CT for HT. RESULTS: A total of 108 patients were enrolled in the study; 58 (53.7%) patients presented with hyperdense lesions on flat-panel CT. Patients with hyperdense lesions experienced a higher proportion of HT than patients without (58.7% vs. 10.0%; P < 0.001). Among all patients with hyperdensity on flat-panel CT, patients who experienced HT had higher average Hounsfield units (HUavg) (125 vs. 93; P = 0.001) and a higher proportion of mass effect (67.6 vs. 12.5; P < 0.001). The flat-panel CT differentiating HT from contrast exudation yielded a sensitivity of 87.2% and a negative predictive value of 90.0%. The area under the curve of HUavg, mass effect, and combination for differentiation of HT were 0.74, 0.78, and 0.83, respectively. CONCLUSION: The hyperdensity on immediately post-thrombectomy flat-panel CT could differentiate HT from contrast exudation with an excellent negative predictive value. The ability of flat-panel CT in differentiating HT from contrast exudation was improved when combined with HUavg and mass effect.

Superior Gas Barrier Properties of Biodegradable PBST vs. PBAT Copolyesters: A Comparative Study.

As a bio-based counterpart of poly(butylene adipate-co-terephthalate) (PBAT), the well-known commercially available biodegradable aliphatic-aromatic copolyester, poly(butylene succinate-co-terephthalate) (PBST) has comparable physical and mechanical properties, but its gas barrier properties, which are very important for packaging material and mulch film applications, have not yet been reported in literature. In this paper, the O2, CO2 and water vapor barrier properties of PBST vs. PBAT were comparatively studied and reported for the first time. Theoretical calculation of O2 and CO2 permeation coefficients via group contribution method was also conducted. The barrier properties of PBST show clear copolymer composition dependence due to different contribution of BS and BT repeat units and composition-dependent crystallinity. Comparing with PBAT, PBST with close copolymer and three-phase (crystalline, amorphous, rigid amorphous) compositions shows 3.5 times O2 and CO2 and 1.5 times water vapor barrier properties. The slower segment movement and less free volume of PBST, and therefore slower gas diffusion in PBST, accounts for its superior O2 and CO2 barrier, while the better hydrophilicity of PBST counteracts partial contribution of slower segment movement so that the improvement in water vapor barrier is not as high as in O2 and CO2 barrier.

A high-throughput homogeneous immunoassay based on Förster resonance energy transfer between quantum dots and gold nanoparticles.

A novel homogeneous immunoassay based on Förster resonance energy transfer for sensitive detection of tumor, e.g., marker with carcinoembryonic antigen (CEA), was proposed. The assay was consisted of polyclonal goat anti-CEA antibody labeled luminescent CdTe quantum dots (QDs) as donor and monoclonal goat anti-CEA antibody labeled gold nanoparticles (AuNPs) as acceptor. In presence of CEA, the bio-affinity between antigen and antibody made the QDs and AuNPs close enough, thus the photoluminescence (PL) quenching of CdTe QDs occurred. The PL properties could be transformed into the fluorometric variation, corresponding to the target antigen concentration, and could be easily monitored and analyzed with the home-made image analysis software. The fluorometric results indicated a linear detection range of 1-110 ng mL(-1) for CEA, with a detection limit of 0.3 ng mL(-1). The proposed assay configuration was attractive for carcinoma screening or single sample in point-of-care testing, and even field use. In spite of the limit of available model analyte, this approach could be easily extended to detection of a wide range of biomarkers.

Detection of MUC-1 protein and MCF-7 cells based on fluorescence resonance energy transfer from quantum dots to graphene oxide.

In this work, an effective sensing platform based on fluorescence resonance energy transfer (FRET) from quantum dots (QDs) to graphene oxide (GO) was developed. Firstly, the aptamer of MUC-1 protein was coupled to CdTe QDs. The interactions between MUC-1 aptamer and GO made CdTe QDs close to GO, which quenched the fluorescence of QDs because of the FRET. However, the stronger interaction between MUC-1 and aptamer weakened the interaction between aptamer and GO, which led to the release of CdTe QDs from GO and thus, the recovery of QDs fluorescence. Based on this, the method was used to detect MUC-1. This approach was successfully extended to detect MCF-7 cells through its interaction with MUC-1 aptamer. The detection limits of MUC-1 and MCF-7 cells were 16 nM and 36 cells/mL, respectively. The method could be extended for detection of other biomolecules by substituting aptamer and the corresponding target.

Polymer-functionalized silica nanosphere labels for ultrasensitive detection of tumor necrosis factor-alpha.

A signal amplification strategy for sensitive detection of tumor necrosis factor-alpha (TNF-α) using quantum dots (QDs)-polymer-functionalized silica nanosphere as the label was proposed. In this approach, silica nanospheres with good monodispersity and uniform structure were employed as carriers for surface-initiated atom transfer radical polymerization of glycidyl methacrylate, which is readily available functional monomer that possessing easily transformable epoxy groups for subsequent CdTe QDs binding through ring-open reaction. Then, human anti rabbit TNF-α antibody (anti-TNF-α, Ab2, served as a model protein) was bonded to CdTe QDs-modified silica nanospheres coated with polymer to obtain QDs-polymer-functionalized silica nanosphere labels (Si/PGMA/QD/Ab2). The Si/PGMA/QD/Ab2 labels were attached onto a gold electrode surface through a subsequent "sandwich" immunoreaction. This reaction was confirmed by scanning electron microscopy (SEM) and fluorescence microscopic images. Enhanced sensitivity could be achieved by an increase of CdTe QD loading per immunoassay event, because of a large number of surface functional epoxy groups offered by the PGMA. As a result, the electrochemiluminescence (ECL) and square-wave voltammetry (SWV) measurements showed 10.0- and 5.5-fold increases in detection signals, respectively, in comparison with the unamplified method. The detection limits of 7.0 pg mL(-1) and 3.0 pg mL(-1) for TNF-α antibodies by ECL and SWV measurements, respectively, were achieved. The proposed strategy successfully demonstrated a simple, reproducible, specific, and potent method that can be expanded to detect other proteins and DNA.

Simultaneous detection of dual proteins using quantum dots coated silica nanoparticles as labels.

Simultaneous detection of multianalytes associated with a particular cancer is beneficial for disease diagnosis. Here, a facile immunosensing strategy was designed to allow simultaneous electrochemical detection of dual proteins, in a single run. CdSe and PbS water-soluble quantum dots (QDs) were prepared and coated on monodisperse silica nanoparticles as labels for proteins detection. Rabbit immunoglobulin G antigen (IgG) and carcinoembryonic antigen (CEA) were chosen as model proteins for analysis. After a typical sandwich immunoassay, CdSe and PbS QDs labels were introduced onto the Au substrates' surface, which were then dissolved and could be simultaneously monitored by square-wave-voltammetric (SWV) stripping measurements. Under selected conditions, IgG and CEA could be assayed in the ranges of 0.05-40 ng mL(-1) and 0.05-25 ng mL(-1), respectively. The proposed method possessed high sensitivity, good precision, and satisfactory reproducibility and regeneration.