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We have developed a highly sensitive colorimetric sensor for the detection of heparin based on its anti-aggregation effect of the PDDA–gold nanoparticle colloidal system.

Plants are exposed to increasingly severe drought events and roots play vital roles in maintaining plant survival, growth, and reproduction. A large body of literature has investigated the adaptive responses of root traits in various plants to water stress and these studies have been reviewed in certain groups of plant species at a certain scale. Nevertheless, these responses have not been synthesized at multiple levels. This paper screened over 2000 literatures for studies of typical root traits including root growth angle, root depth, root length, root diameter, root dry weight, root-to-shoot ratio, root hair length and density and integrates their drought responses at genetic and morphological scales. The genes, quantitative trait loci (QTLs) and hormones that are involved in the regulation of drought response of the root traits were summarized. We then statistically analyzed the drought responses of root traits and discussed the underlying mechanisms. Moreover, we highlighted the drought response of 1-D and 2-D root length density (RLD) distribution in the soil profile. This paper will provide a framework for an integrated understanding of root adaptive responses to water deficit at multiple scales and such insights may provide a basis for selection and breeding of drought tolerant crop lines.

In this work, an ultrasensitive method for trace protein detection based on fluorescent carbon nanodots and hybridization chain reaction (HCR) is designed. Generally, the synthesized bright carbon nanodots are conjugated with two hairpin‐structured DNA probes, respectively, which act as subsequent HCR fuel strands. Since single‐stranded parts of DNA probes could be easily absorbed on graphene oxide (GO) nanosheets, fluorescence emission of carbon nanodots is effectively quenched via fluorescence resonance energy transfer. However, in the presence of target protein, the aptamer sequence in another hairpin‐structured DNA probe specially interacts with target and the hairpin is opened. A single‐stranded region is thus exposed, which initiates HCR by coupling with the DNA fuel strands on carbon nanodots. The formed HCR product displays a rigid, long double‐stranded structure, which facilitates the release of carbon nanodots from GO surface. As a result, fluorescence of carbon nanodots is recovered and initial concentration of target protein can be estimated. This protein detection method shows a favorable linear response with a low limit of detection (2.3 fg mL−1). Furthermore, it is highly selective and capable of detecting target in biological fluids like serum samples, which demonstrates the promising applications of this method.

Herein, we have developed a dual amplification strategy for ultrasensitive detection of DNA combining exonuclease III (Exo III)-assisted reaction and DNAzyme motor. DNA probes are carefully designed; thus, target recognition and the first amplification cycle are accomplished simultaneously, which makes the operation very convenient. Moreover, the self-powered DNAzyme motor may translate a single binding event into cleavage of multiple fluorescence probes, which significantly heightens the signal intensity. As a result, the limit of detection as low as 21 fM is achieved. The fluorescence intensity is found to have a linear relationship with respect to the logarithm of DNA concentration in a wide range from 100 fM to 10 nM. This proposed method shows great potential for the applications of biological studies and clinical diagnosis.

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