Ultrasensitive Detection of Prostate Specific Antigen by an Unlabeled Fluorescence Aptasensor Based on the AIE Effect.

The accurate and sensitive detection of prostate specific antigen (PSA) is vital for the early diagnosis and treatment of prostate cancer. To this end, an unlabeled fluorescent aptasensor was constructed by using a novel Compound B {1,1'-(1,4-phenylene) bis(3-ethyl-1H-imidazol-3-ium) iodide} with aggregation-induced emission (AIE) activity as a fluorescence signal and NH2-Fe3O4 particle as an adsorption platform. Compound B could combine with prostate specific antigen aptamers (PSA-Apt) to form a PSA-Apt/B complex, which further generated the AIE effect. Then, PSA was added to the PSA-Apt/B solution. PSA combined with PSA-Apt/B to form the PSA-Apt/B/PSA complex. Next, NH2-Fe3O4 magnetic particles were added to the solution. Given that PSA-Apt/B/PSA would no longer combine with NH2-Fe3O4 magnetic particles, the PSA-Apt/B/PSA complex remained in the supernate after magnet separation, and the supernate showed strong fluorescence (I). When no PSA was added to the PSA-Apt/B solution, PSA-Apt/B could combine with NH2-Fe3O4 magnetic particles and would be sucked into the bottom of the test tube by magnet, and the supernate would show weak fluorescence (I0). Result showed that the difference between the above-mentioned two fluorescence values (∆I = I - I0) had an excellent linear relationship with the PSA concentration within the concentration range of 0.01-10 ng/mL, and its limit of detection was 3 pg/mL (S/N = 3). In addition, the sensor has high accuracy and can be directly used to test PSA in actual serum samples.

Fluorometric detection of alpha-fetoprotein based on the use of a novel organic compound with AIE activity and aptamer-modified magnetic microparticles.

BACKGROUND: Liver cancer is one of the most common cancers in the world, and it seriously threatens human life and health. Alpha-fetoprotein (AFP), as a carcinogenic glycoprotein, is an important serum marker for detecting liver cancer. Therefore, the accurate and sensitive determination of AFP is crucial for the early diagnosis and treatment of liver cancer. To this end, a label-free fluorescence aptasensor for detecting AFP based on the use of a novel organic Compound D with an aggregation-induced emission activity and aptamer-modified magnetic microparticles was constructed. RESULTS: Compound D could combine with the complementary short chain of the aptamer (CSC-Apt) of AFP to form the D/CSC-Apt complex and realize the fluorescence enhancement of Compound D. Then, magnetic particles modified by the Apt of AFP (Apt-Fe3O4) were prepared. When AFP (or nontarget substance) and D/CSC-Apt were successively added to the Apt-Fe3O4 solution, Apt-Fe3O4 selectively bound to AFP or the D/CSC-Apt complex. Magnetic separation technology showed the changes in the fluorescence intensity of the supernatant. The research results revealed a good linear relationship between the changes in the fluorescence intensity of the supernatant and concentration of AFP within the concentration range of 10-10000 pg mL-1. The proposed aptasensor could achieve high-sensitivity and high-specificity detection of AFP, and its limit of detection was 3 pg mL-1 (S/N = 3). SIGNIFICANCE AND NOVELTY: The sensor combines the advantages of high selectivity of Apt, high sensitivity of fluorescence analysis, AIE effect and good water solubility of Compound D, and rapid separation using magnetic separation technology. And it can be directly used for the detection of AFP in actual serum samples with high accuracy, whereas most of the methods reported in the literature can only detect AFP in spiked serum samples.

Sensitive determination of prostate-specific antigen with graphene quantum dot-based fluorescence aptasensor using few-layer V2CTx MXene as quencher.

A novel fluorescence aptasensor of prostate-specific antigen (PSA) was established using few-layer vanadium carbide (FL-V2CTx) nanosheet as a quencher. First, FL-V2CTx was prepared by the delamination of multi-layer V2CTx (ML-V2CTx) with tetramethylammonium hydroxide. The aptamer-carboxyl graphene quantum dots (CGQDs) probe was prepared by combining the aminated PSA aptamer and CGQDs. Then, the aptamer-CGQDs were absorbed onto the surface of FL-V2CTx by hydrogen bond interaction, which led to the decrease in fluorescence of aptamer-CGQDs due to photoinduced energy transfer. After addition of PSA, PSA-aptamer-CGQDs complex was released from FL-V2CTx. The fluorescence intensity of aptamer-CGQDs-FL-V2CTx with PSA was higher than that without PSA. The FL-V2CTx-based fluorescence aptasensor provided a PSA detection linear range from 0.1 to 20 ng mL-1 with detection limit of 0.03 ng mL-1. The ΔF value of fluorescence intensities for aptamer-CGQDs-FL-V2CTx with and without PSA was 5.6, 3.7, 7.7, and 5.4 times of ML-V2CTx, few-layer titanium carbide (FL-Ti3C2Tx), ML-Ti3C2Tx and graphene oxide aptasensors, respectively, indicating the advantage of FL-V2CTx. The aptasensor had high selectivity for PSA detection compared with some proteins and tumor markers. This proposed method had convenience and high sensitivity for PSA determination. The determination results of PSA in human serum samples using the aptasensor were consistent with those by chemiluminescent immunoanalysis. The fluorescence aptasensor can be successfully applied for PSA determination in serum samples of prostate cancer patients.

A novel fluorescence aptasensor based on PCN-223 as an efficient quencher for sensitive determination of prostate-specific antigen.

A novel fluorescence aptasensor based on PCN-223 as an efficient quencher was developed to sensitively detect prostate-specific antigen (PSA). The 5-carboxytetramethylrhodamine (TAMRA)-labeled PSA aptamer was adsorbed on PCN-223 by π-π stacking and hydrogen-bonding interactions, which contributed to fluorescence quenching because of the photoinduced electron transfer from TAMRA to PCN-223. In addition, the amount of quenched fluorescence of the PSA-binding aptamer complex-PCN-223 was lower than that of TAMRA aptamer-PCN-223 without PSA (at excitation/emission peaks of 545/582 nm), which can be explained by the fact that the PSA-binding aptamer complexes contributed to the separation of the aptamer from PCN-223. ∆F value of fluorescence intensities for TAMRA aptamer-PCN-223 with and without PSA showed a good linear relationship with PSA concentration over a range of 0.1 to 24 ng mL-1, with a detection limit of 0.05 ng mL-1. Compared with three metal-organic frameworks (MOFs) of UiO-66-NH2, ZIF-67, and Ni3(HITP)2 as quenchers, PCN-223 as a Zr-MOF exhibited the highest ∆F value for PSA detection. The advantage of PCN-223 could be attributed to its carboxyl, benzene, and porphyrin groups, the large specific surface area and good biocompatibility. This proposed aptasensor can be successfully used to detect PSA in sera of prostate cancer patients. The PSA detection results of this aptasensor were consistent with those which were obtained from hospital by Archtecti2000sr automatic chemiluminescence immunoanalyzer. The proposed aptasensor has potential clinical detection application.

A label-free fluorescent aptasensor based on the AIE effect and CoOOH for ultrasensitive determination of carcinoembryonic antigen.

Highly sensitive and specific detection of cancer markers (such as carcinoembryonic antigen) is very important for early diagnosis and treatment of cancer. Herein, we developed a label-free fluorescent aptamer biosensor based on the aggregation-induced emission (AIE) effect and hydroxycobalt oxide (CoOOH) platform, and used it to detect carcinoembryonic antigen (CEA) with high sensitivity and specificity. Fluorescent ionic liquid Compound B can combine with a CEA aptamer (CEA-Apt) through electrostatic attraction and hydrophobic interaction to form an ionic liquid/aptamer (CEA-Apt/B) complex and produce the AIE effect, thereby enhancing the fluorescence intensity of B. CEA-Apt/B was adsorbed on the surface of CoOOH when CoOOH was added to the buffer solution, and the fluorescence of B was quenched. After adding CEA to the solution, CEA-Apt/B bound to CEA and separated from the surface of CoOOH because CEA-Apt had stronger affinity for CEA, resulting in fluorescence recovery of B. In the level range of 0.67-10000 pg mL-1, the fluorescence recovery intensity of the sensor had an excellent linear relationship with the level of CEA, and its LOD was 0.2 pg mL-1 (S/N = 3). In addition, the sensor had good selectivity and can be directly used to detect CEA in human serum with high accuracy.