Dajiao Cheng,Rong Liu,Limei Tian,Quan Zhou,Fushuang Niu,Yinghong Yue,Ke Hu
Photocatalytic activation of prodrugs for killing cancer cells is an attractive alternative phototherapy to photodynamic therapy that typically relies on the supply of oxygen. Although prodrugs are widely developed, few other than Pt(IV) complexes are studied for photocatalytic activation. Herein, we report the photocatalytic reduction of nitrobenzene to aniline, an important chemical conversion for a large class of nitroaromatic prodrugs in cancer therapy that was previously limited to only enzyme-catalyzed activation. The carefully designed photocatalyst is a photosensitizer (PS)-functionalized gold nanocluster (Au NC) (abbreviated as Au-PS) in which a ruthenium coordination compound as the PS is covalently linked to the glutathione-ligated Au NC surface. Visible light excitation of the photocatalyst reduces nitrobenzene to aniline with 100% selectivity. The remarkably high selectivity is attributed to the specific catalytic nature of the reduced Au NC from photoinduced charge separation within the Au-PS analyzed by time-resolved absorption spectroscopy. In vitro experiments show that the nitroaromatic prodrug 5-(aziridin-1-yl)-2,4-dinitrobenzamide (CB1954) induces significant cytotoxicity in the presence of the Au-PS and light under hypoxia. The photocatalytic nitroaromatic prodrug activation by the Au-PS provides an alternative approach in the category of photochemotherapy to confront hypoxic cancer cells.
Li Wang,Jianli Sun,Xiaoxuan Wang,Milan Lei,Zengliang Shi,Lei Liu,Chunxiang Xu
Rapid and sensitive detection of multiple biomarkers by lateral flow immunoassay (LFIA) remains challenging for signal amplification for commonly used nanotags. Herein, we report a novel LFIA strip for visual and highly sensitive analysis of two cardiac biomarkers based on functionalized gold nanoparticles @ polystyrene microsphere (Au@PS）microcavity as surface-enhanced Raman scattering (SERS) tags. Antibody-modified Au@PS was designed as a SERS label. The evanescent waves propagating along the surface of the PS microcavity and the localized surface plasmons of the gold nanoparticles were coupled to enhance the light-matter interaction synergistically for Raman signal enhancement. In this strategy, the proposed Au@PS SERS tags-based LFIA was carried out to quantify the content of the heart failure and infarct biomarkers synchronously within 15 min and get the limits of detection of 1 pg/mL and 10 pg/mL for cardiac troponin I (cTnI) and N-terminal natriuretic peptide precursor (NT-proBNP), respectively. The results demonstrated 10–20 folds more sensitivity than that of the standard colloidal gold strip and fluorescent strip for the same biomarkers. This novel quantitative LFIA shows promise as a high-sensitive and visual sensing method for relevant clinical and forensic analysis.
Reliable quantification by surface enhanced Raman scattering (SERS) highly depends on the development of a reproducible substrate with excellent anti-interference capability. In this work, an intrinsic internal standard (IS) SERS substrate based on a diblock copolymer, polystyrene-block-poly-4-vinylpyridine (PS-b-P4VP), as a template was developed by a modified block copolymer lithography (BCL) technique of reserving the diblock copolymer template. This substrate generated a stable vibration peak at 1066 cm−1 attributed to poly(4-vinylpyridine) (P4VP) which could be used as an intrinsic IS for precise SERS quantification. A series of characterization results showed that the diblock copolymer template endowed this substrate with homogeneous distribution of Au nanoparticles, excellent stability and reproducibility. A minor relative standard deviation (RSDs) of SERS responses at 1066 cm−1 was measured and calculated to be 4.3% from ten different substrates in the same batch, which suggested good substrate-to-substrate reproducibility of this substrate. Finally, this intrinsic IS substrate was successfully applied for the rapid quantification of a trace banned dye, chrysoidine, in food samples with complicated matrices by SERS. It was proved that chrysoidine could be found and quantified to be 0.50 and 0.41 mg L−1 in a positive dried bean curd stick and chilli powder sample respectively with good recoveries by this substrate coupled with SERS. The development of intrinsic IS substrates would benefit rapid and accurate quantification of trace targets in complex samples coupled with SERS analysis.
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