Lan Wu

Fast Imaging of Eccrine Latent Fingerprints with Nontoxic Mn-Doped ZnS QDs

Fingerprints are unique characteristics of an individual, and their imaging and recognition is a top-priority task in forensic science. Fast LFP (latent fingerprint) acquirement can greatly help policemen in screening the potential criminal scenes and capturing fingerprint clues. Of the two major latent fingerprints (LFP), eccrine is expected to be more representative than sebaceous in LFP identification. Here we explored the heavy metal-free Mn-doped ZnS quantum dots (QDs) as a new imaging moiety for eccrine LFPs. To study the effects of different ligands on the LFP image quality, we prepared Mn-doped ZnS QDs with various surface-capping ligands using QDs synthesized in high-temperature organic media as starting material. The orange fluorescence emission from Mn-doped ZnS QDs clearly revealed the optical images of eccrine LFPs. Interestingly, N-acetyl-cysteine-capped Mn-doped ZnS QDs could stain the eccrine LFPs in as fast as 5 s. Meanwhile, the levels 2 and 3 substructures of the fingerprints could also be simultaneously and clearly identified. While in the absence of QDs or without rubbing and stamping the finger onto foil, no fluorescent fingerprint images could be visualized. Besides fresh fingerprint, aged (5, 10, and 50 days), incomplete eccrine LFPs could also be successfully stained with N-acetyl-cysteine-capped Mn-doped ZnS QDs, demonstrating the analytical potential of this method in real world applications. The method was also robust for imaging of eccrine LFPs on a series of nonporous surfaces, such as aluminum foil, compact discs, glass, and black plastic bags.

Inductively coupled plasma mass spectrometry for determination of total urinary protein with CdTe quantum dots label

In the present work, a novel methodology for sensitive quantification of human total urinary protein by using CdTe quantum dots label and inductively coupled plasma mass spectrometry (ICP-MS) was developed. It combined the intrinsically high sensitivity of elemental mass spectrometric analysis with the remarkable quantity of metallic ions from the nanoparticles label. Through the direct conjugation of CdTe quantum dots and proteins, the ICP-MS signal intensity of cadmium is proportional to the concentration of proteins. The optimization of bio-conjugation parameters was investigated and discussed in detail. The proposed method featured a low detection limit (0.008 μg mL−1 for HSA) and wide linear range response over 4 orders of magnitude. Moreover, there are very little interferences from common inorganic ions and other coexisting compounds. The developed method was successfully applied for detecting total protein in 50 human urine samples and the results were in good agreement with those reported by the hospital, which indicated a great potential for routine clinical application.

UV-Induced Surface Photovoltage and Photoluminescence on n-Si/TiO2/TiO2:Eu for Dual-Channel Sensing of Volatile Organic Compounds

In this work, a novel dual-channel sensing mode, i.e., UV-induced surface photovoltage (SPV) and photoluminescence (PL) on n-type Si/TiO(2)/Eu(3+)-doped TiO(2) (n-Si/TiO(2)/TiO(2):Eu), was demonstrated for the discrimination of 20 volatile compounds. The SPV signaling in this work employed a laboratory-constructed microvoltammeter with good analytical performances. This device also features wireless communication, portability, along with low cost and power consumption. The SPV and PL pattern of each analyte was distinct, and the hierarchical clustering analysis (HCA) result showed that these 20 volatile species were distinguishable, even for structural isomers. Linear discriminant analysis (LDA) further demonstrated the robustness of this sensor: 180 unknown samples from three groups at concentrations of 15.3, 31.7, and 79.2 mg/L were classified with accuracies of 96.7%, 95.0%, and 100%, respectively. Principal component analysis (PCA) revealed that SPV and PL channels contributed equally to the good discrimination ability due to two distinct sensing mechanisms. This dual-channel sensor was also successfully applied in the discrimination of beverage samples such as liquor, wine, and vinegar.

Porous chitosan/hydroxyapatite composite membrane for dyes static and dynamic removal from aqueous solution

The unique characteristics of Chitosan (CS) such as resource abundance, good biocompatibility, film-forming ability and sufficient sites (NH2 and OH) for adsorption of heavy metals or organic pollutants make CS-based membranes a promising membrane adsorbent. In this work, a porous Chitosan/Hydroxyapatite (CS/HA) membrane with a sponge-like surface and a three-dimensional interpenetrated porous structure of about mean pore size less than 10μm was developed. The most striking advantage of the proposed membrane lies on the integration of appreciably high adsorption capacity (as compared with current CS-based membranes, also 2.5 times and 4 times higher than that of non-porous CS/HA membrane and the commercially available activate carbon) and the high-speed dynamic dye removal (98% or even better in less than 15min). Besides, the synthesis protocol for the proposed membrane is also much simpler, environmental-friendly and economical. Moreover, the proposed membrane also featured repeated dye removal (above 80% after 5 cycles of dynamic adsorption at dye concentration of 150mgL-1). All the above advantages indicated the intriguing potential of the porous membrane in practical wastewater treatment.

Applications of silica-based nanoparticles for multimodal bioimaging

ABSTRACT Multimodal imaging, as an important approach to circumvent the limitations of single imaging modality, has attracted extensive attention in recent years. With the rapid development of nanotechnology and the ongoing efforts to improve their targeting capability and endow multiple imaging ability, nanoprobes are expected to play crucial roles in multimodal imaging through integrating different imaging moieties or molecules into a single nanoparticle, where silica has been used intensively as a carrier or a medium for the construction of the nanoprobes due to its preferable characteristics including good biocompatibility, long blood circulation time, and ease of modification. Based on the types of the silica used for the fabrication of nanoprobes, solid silica-based and mesoporous silica-based nanoparticles were developed for multimodal imaging. Herein, the newly developed silica-based nanoparticles as multimodal imaging agents for disease diagnosis and therapy in the last 5 years were summarized, along with their fabrication process, specific applications, and especially the role of the silica.