Both the 3D solution and the 2D interface play important roles in bioanalysis.For the former, reactions can be carried out adequately; while for the latter, interfering substance can be eliminated simply through wash.It is a challenge to integrate the advantages of solution-based assays and the interface-based assays.Here, we report an immuno-NRCA (netlike rolling circle amplification) strategy, which integrates immunoassay with NRCA for the ultrasensitive detection of tumor biomarker, by taking the assay of a tumour marker as an example.In this strategy, immunoreactions occur on interface, while the target-induced signal amplification can be completed totally in solution.As a result, this system has the merits of both solution-and interface-based assays.The whole procedure of this novel strategy is similar to the conventional ELISA, inheriting the usability.But in comparison with ELISA, the performance is greatly improved.The detection limit can be lowered to 5.5 fg/L, making it possible to detect the target tumour marker in one drop of blood.Also, in comparison with established immuno-PCR method, which integrates immunoassay with the commonly used nucleic acid amplification approach, this system has no requirement for thermal cycler owing to the isothermal amplification, and it has the ability to retain the immunoreactivities.So, the new immunoassay method proposed in this study may have more feasible applications in the future.
Cancer is a global disease which has been disturbing researchers in medicine and seriously threatens patients’ health and lifetime around the world in the past several decades. Due to the characteristics of cancer cells, such as uncontrollable cell proliferation, cell invasion and metastasis to surrounding tissues, lower grade of differentiation, higher telomerase activity and others, it has been one of the most usual lethal factors, next to heart disease in incidence. Cancer mortality can be decreased by early diagnosis, and the people who with treatment at an early stage have an obvious improved survival rate. Consequently, early detection is significant for better understanding the pathogenesis of cancer and improving the prognosis of patients. In situ detection technique is a vital tool for imaging and cellular pathology research, which can provide effective information about tumor markers in the early cancer detection. In view of low expression of most tumor markers in the early stage of cancers, detection techniques based on DNA signal amplification and DNA nanodevices can provide a strong support for the diagnosis and detection of cancers. In this review, we summarize the research progress of different analytical techniques for detecting various tumor markers that have been reported in recent years. We compare different DNA amplification and nanodevices, then provide guidance and suggestions for better understanding in situ analysis of cancer cells.
Nanoscale dual-wavelength lasers are attractive for their potential applications in highly integrated photonic devices. Here we report the growth of nanoribbon lateral heterostructures made of a CdS(x)Se(1-x) central region with epitaxial CdS lateral sides using a multistep thermal evaporation route with a moving source. Under laser excitation, the emission of these ribbons indicates sandwich-like structures along the width direction, with characteristic red emission in the center and green emission at both edges. More importantly, dual-wavelength lasing with tunable wavelengths is demonstrated at room temperature based on these single-nanoribbon heterostructures for the first time. These achievements represent a significant advance in designing nanoscale dual-wavelength lasers and have the potential to open up new and exciting opportunities for diverse applications in integrated photonics, optoelectronics, and sensing.
Abstract Accurate and efficient molecular recognition plays a crucial role in the fields of molecular detection and diagnostics. Conventional trial‐and‐error‐based molecular recognition approaches have always been challenged in distinguishing minimal differences between targets and non‐targets, such as single nucleotide polymorphisms (SNPs) of oligonucleotides. To address these challenges, here, a novel concept of dynamic addressing analysis is proposed. In this concept, by dissecting the regions of the target and creating a corresponding recognizer, it is possible to eliminate the inaccuracy and inefficiency of recognition. To achieve this concept, a Dynamic Addressing Molecular Robot (DAMR), a DNA‐based dynamic addressing device is developed which is capable of dynamically locating targets. DAMR is designed to first bind to the conserved region of the target while addressing the specific region dynamically until accurate recognition is achieved. DAMR has provided an approach for analyzing low‐resolution targets and has been used for analyzing SNP of miR‐196a2 in both cell and serum samples, which has opened new avenues for effective and efficient molecular recognition.
Methylammonium lead halide perovskites have attracted enormous attentions due to their superior optical and electronic properties. However, the photodetection at near‐infrared telecommunication wavelengths is hardly achievable because of their wide bandgaps. Here, this study demonstrates, for the first time, novel perovskite–erbium silicate nanosheet hybrid photodetectors with remarkable spectral response at ≈1.54 µm. Under the near‐infrared light illumination, the erbium silicate nanosheets can give strong upconversion luminescence, which will be well confined in their cavities and then be efficiently coupled into and simultaneously excite the adjacent perovskite to realize photodetection. These devices own prominent responsivity and external quantum efficiency as high as previously reported microscale silicon‐based subbandgap photodetectors. More importantly, the photoresponse speed (≈900 µs) is faster by five orders than the ever reported hot electron silicon‐based photodetectors at telecommunication wavelengths. The realization of perovskite‐based telecommunication band photodetectors will open new chances for applications in advanced integrated photonics devices and systems.
In this work, we proposed a novel simple protocol for preparing 1-aminopyrene/graphene (ApG) hybrids for fabricating label-free electrochemical impedance genosensor. Graphene, with the structure of a single-atom-thick sheet of sp2-bonded carbon atoms, was anchored to 1-aminopyrene (1-Ap) with the pyrenyl group via π-stacking interaction. The morphology, conductivity, and interaction of ApG hybrids were characterized by transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), UV-visible (UV-vis) and fluorescence spectra. The amino-substituted oligonucleotide probe was conjugated to 1-Ap by the cross-linker glutaraldehyde. The DNA hybridization reaction of oligonucleotide probe with target DNA was monitored by EIS. Under optimum conditions, the proposed biosensor exhibited high sensitivity and a low detection limit for detecting the complementary oligonucleotide. The target oligonucleotide could be quantified in a wide range of 1.0 × 10−12 to 1.0 × 10−8 M with good linearity (R = 0.9900) and low detection limit of 4.5 × 10−13 M (S/N = 3).
Substitutional doping lanthanide ions (Ln3+) in CsPbX3 has been proven to be an efficient strategy for expanding the properties of the perovskite (PVK). Here, erbium (Er3+) uniformly doped CsPbX3 perovskite microplates are grown through a chemical vapor deposition method. Two fluorescence peaks at 430 and 520 nm which respectively correspond to the PVK and Er3+ emissions are observed. The time-resolved photoluminescence of both PVK host and Er dopants demonstrates that trap states play a critical role in facilitating the energy transfer between the PVK host and the Er dopants, which is vital to sensitizing the Er3+. A photophysical model was put forward to comprehensively describe this trap-mediated energy-transfer process, and the dynamics processes are modeled using correlated rate equations. The rates of the carrier's relaxation and energy transfer are respectively obtained as 6.6 and 49 ns-1, and a total energy transfer efficiency was obtained as ∼32.6%.
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