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A SERS active bimetallic core-satellite nanostructure for the ultrasensitive detection of Mucin-1
Jingjing Feng, Xiaoling Wu, Wei Ma, Hua Kuang, Liguang Xu, Chuanlai Xu*
Received (in XXX, XXX) Xth XXXXXXXXX 201X, Accepted Xth XXXXXXXXX 201X
First published on the web Xth XXXXXXXXX 201X 5
In this study, we established gold nanorods (Au NRs) core-silver nanoparticles (Ag NPs) satellite assemblies as an ultrasensitive aptamer-based SERS sensor for the detection of 10
Mucin-1, a specific breast cancer marker protein. The limit of detection (LOD) was 4.3 aM and the wide linear range was 0.005-1 fM.
Cancer is a fatal disease with a high mortality rate, and the global burden of cancer continues to increase1. Breast cancer is 15 the most frequently diagnosed cancer and the leading cause of cancer death among females worldwide2. Despite diagnostic improvements during the last few decades, the detection of breast cancer in the early stages is still a huge challenge3-5. Sensitive monitoring of tumor biomarkers in the blood or other body fluids 20 is an effective diagnostic method for the early detection of malignancies6. Mucin-1, which is abnormally expressed in diseased tissues compared with normal tissues, is the most common tumor marker used to diagnose breast tumors7, 8.
Therefore, enhancing the detection level of Mucin-1 using an 25 ultrasensitive and highly selective analytical assay plays an important role in the early diagnosis of breast cancer.
To date, only a few studies have investigated the identification and quantification of Mucin-1, and the techniques used have included an antibody-mediated Si nanowire field-effect 30 electrical sensor6, a graphene oxide-based fluorescent aptasensor7, and an aptamer-antibody hybrid sandwich ELISA9.
These studies provided a novel concept for the diagnosis of breast cancer in the early stages. However, the antibody was expensive and the enzyme labeling procedure was complicated, the 35 graphene oxide-based modification steps were tedious and the sensing sensitivity was limited. Thus, a rapid detection technique with high selectivity and sensitivity, for early diagnosis with the potential for further improvement is needed.
Surface enhanced Raman scattering (SERS), is a promising 40 ultra-sensitive technique for chemical and biological molecular species, and has received significant attention10-13. The merits of
SERS include fast detection time, highly sensitive detection over a wide range of excitation wavelengths, and excellent reproducibility with a relative standard deviation. Importantly, 45 metallic nanostructures are frequently used as SERS substrates and have been shown to be associated with enhanced intensity of characteristic spectral signals11, 14-18. This enhanced intensity is largely attributed to high local electromagnetic field intensities generated in the vicinity of the metal nanoparticles. In particular, 50 it has been demonstrated that strongly coupled plasmonic assemblies have intense electromagnetic hot-spots and can yield extraordinary enhancement factors for SERS14, 19-24. For instance,
Gandra and his co-workers25 found that the core-satellite structures assembled by gold nanoparticles could lead to a 55 remarkable enhancement of Raman scattering by the synergistic combination of many in-built electromagnetic hot-spots among assemblies. Interestingly, the number of nanoparticles in the assemblies had a great influence on the intensity of SERS which could be significantly improved the sensitivity of detection. 60
In this study, a novel assembled structure with gold nanorod (Au NR) as a core and multiple silver nanoparticles (Ag NPs) as satellites were constructed. Ag NPs were demonstrated as perfect candidates for SERS probes with higher enhancement than gold nanoparticles26. Importantly, due to rod-like gold nanoparticles’ 65 intense and aspect ratio-dependent longitudinal surface plasmon resonance, Au NRs with greater local field effect show a huge enhancement of Raman signals27. Coupled with many intense electromagnetic hot-spots were developed, the Au NRs core-Ag
NPs satellites assemblies could be ideal SERS substrates with 70 expressively improved of the intensity of SERS and sensitivity of detection.
We established the core-satellite structures using DNA as the linker. The aptamer for the designated disease biomarker Mucin1 and partial complementary sequences were coupled to the Ag 75
NPs and Au NRs, respectively. The functionalized nanostructures were then mixed with the Au NRs core-Ag NPs satellite assemblies following DNA hybridization in the absence of the target Mucin-1, as illustrated in Scheme 1. Subsequently, in the presence of Mucin-1, the high specific biorecognition of aptamer 80 and Mucin-1 caused the release of the core-satellite assemblies.