A simple method termed immunological multimetal deposition (iMMD) was developed for rapid visualization of sweat fingerprints with bare eyes, by combining the conventional MMD with the immunoassay technique. In this approach, antibody-conjugated gold nanoparticles (AuNPs) were used to specifically interact with the corresponding antigens in the fingerprint residue. The AuNPs serve as the nucleation sites for autometallographic deposition of silver particles from the silver staining solution, generating a dark ridge pattern for visual detection. Using fingerprints inked with human immunoglobulin G (hIgG), we obtained the optimal formulation of iMMD, which was then successfully applied to visualize sweat fingerprints through the detection of two secreted polypeptides, epidermal growth factor and lysozyme. In comparison with the conventional MMD, iMMD is faster and can provide additional information than just identification. Moreover, iMMD is facile and does not need expensive instruments.
This review highlights the considerable advances in the chemical imaging of human fingermarks that provide more chemical information, including numerous endogenous and exogenous constituents. Despite remarkable development in DNA analysis and recognition, human fingermark analysis remains one of the priority approaches available for obtaining reliable forensic evidence. Additional information about the donor can be obtained from the chemical composition of latent fingermarks in addition to the ridge pattern, such as the age, gender, medical history, and possible drug habits. The analytical approaches reviewed here include spectroscopy, mass spectrometry, immuno-labelling and electrochemical methods. Each method has different capabilities with respect to sensitivity, reproducibility, selectivity, reliability and ultimately applicability, either for use in routine forensic practice or in academic research work. The advantages of spectroscopic techniques, including infrared, Raman and micro-X-ray fluorescence spectroscopy, are the capabilities of a rapid and non-destructive imaging of fingermarks by providing spectral information on chemical composition. In addition, mass spectrometry imaging can provide spatially specific information on fingermark chemical composition. Recently, the use of immuno-labelling in latent fingermark detection has attracted significant attention because it can overcome the sensitivity and selectivity problems experienced with other existing methods. The electrochemical method has also been employed to image latent fingermarks by measuring the electric current changes with the spatial chemical composition from the ridges and valleys at high resolution to provide a third level of detail, which is especially useful for multicoloured background surfaces or for surfaces contaminated with blood or other bodily fluids.
As hypoxia is an important factor to limit chemotherapeutic efficacy in tumors, we herein report three ruthenium(II)-arene complexes containing a hypoxia inducible factor-1α inhibitor (YC-1), which endow the organometallic complexes with potential for hypoxia targeting. In vitro tests showed the resulting complexes had higher anticancer activities in hypoxia than in normoxia against the tested cancer cell lines. Western blot analysis revealed that complexes 1-3 blocked HIF-1α protein accumulation under hypoxic conditions. Moreover, these complexes displayed much less cytotoxicity toward the normal human umbilical vein endothelial cell line (HUVEC), indicating that complexes 1-3 may be selectively cytotoxic for human cancer cell lines. These findings proved that ligation with YC-1 endowed these organometallic ruthenium(II) complexes with potential for hypoxia targeting in addition to enhancing their anticancer activities.
In this work, a series of molecules TPE-PA-n (n = 3−11) were designed with classic aggregation-induced emission (AIE) 1,1,2,2-tetraphenylethene (TPE) for self-assembled monolayers (SAMs), which are applied for the detection of trace nitroaromatic compound (NAC) explosives. Phosphoric acid that acts as an anchor is used to connect with TPE through alkyl chains of various lengths. It is found that the alkyl chains play a role in pulling TPE luminogens to aggregate for light emission, which can affect the fluorescence and sensing performance of the SAMs. Ulteriorly, a model is built to explore the influence of the alkyl chain length on the device performance, which is determined by the three effects of the alkyl chain: flexibility, the coupling effect, and the odd−even effect. By comparison, the functional molecules with the chain length of 8 were finally selected and further applied for NAC sensors. By means of fluorescence spectra, the SAM sensor was proved to have good stability, reversibility, selectivity, and sensitivity, and its detection limits for trinitrotoluene, dinitrotoluene, and nitrobenzene were 1.2, 6.0, and 35.7 ppm, respectively. This work provides new ideas for the design and preparation of flexible sensors for trace NAC detection with high performance, low cost, and easy operation.
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