SERS-Active 3D Interconnected Nanocarbon Web toward Nonplasmonic in Vitro Sensing of HeLa Cells and Fibroblasts

Abstract

A noninvasive intracellular component analysis technique is important in cancer treatment and the initial identification of cancer. Carbon nanomaterials/nanostructures, such as carbon nanotubes and graphene, have little to no surface enhanced Raman scattering (SERS) ability. Because of these structures' low Raman responses, they are conjugated with gold or silver to attain the SERS-active ability to detect normal fibroblasts and HeLa cancer cells. To the best of our knowledge, the effectiveness of the individual use of carbon nanomaterials as a nonplasmonic SERS-active platform for in vitro cancer/normal cell detection has not been investigated to date. Here, for the first time, we introduce a unique nonplasmonic SERS-based biosensing platform that uses a biocompatible self-assembled threedimensional interconnected nanocarbon web (INW) for in vitro detection and differentiation of HeLa cells and fibroblasts. The sub-10-nm morphology of the INW facilitates the endocytic uptake of INW clusters to the cells, and its SERS functionality introduces live cell Raman sensing. The INW platform has achieved an enhancement factor (EF) of 3.66 × 10 4 and 9.10 × 10 3 with crystal violet and Rhodamine 6G dyes, respectively, significant in comparison to the EF of graphene surfaces (2−17). The results of the time-based Raman spectroscopy of live HeLa cells and fibroblasts revealed chemical fingerprints of intracellular components, such as DNA/RNA, proteins, and lipids. The components' spectroscopic differences facilitate and elucidate the specification of each cell. The highest Raman enhancement achieved was fourfold for fibroblasts (protein) and sixfold for HeLa cells (DNA). Furthermore, the SERS spectra along with scanning electron microscopy and fluorescence microscopy analysis of the immobilized cells after 24 and 48 h shed light on the health of fibroblasts and HeLa cells. A photon energy-induced ionization achieved with a femtosecond laser fabricated a biocompatible INW platform with the designated unique attributes. This simple, label-free, in vitro diagnosis approach for HeLa cells and fibroblasts has strong potential for cancer research.

Study of Chemical Enhancement Mechanism in Non-plasmonic Surface Enhanced Raman Spectroscopy (SERS)

“…It is reported that SERS enhancement factor (EF) can be as high as 10 12 in some cases (David et al, 2010) indicating that unprecedented area of analyses such as Raman fingerprinting of a very small amount of materials, even of a single molecule may be possible, and hence enormous research efforts have been exerted over the decades (Kneipp et al, 1997; Nie and Emory, 1997; Stiles et al, 2008). Recent applications of SERS include, for example, employing various nanostructured materials (Wang Y. et al, 2012; Jin, 2013; Li et al, 2013, 2017; Xu et al, 2013; Lin et al, 2015; Bakan et al, 2016; Wang et al, 2016; Chowdhury et al, 2018; Yu et al, 2019). SERS is also very interesting because it inherently involves light-matter interaction in small scale where quantum mechanical effects might be crucial.…”

Recent advances in non‐plasmonic surface‐enhanced Raman spectroscopy nanostructures for biomedical applications

“…9,52 Non-plasmonic SERS biosensing can be also realized by 3D interconnected nanocarbon web (INW). 9 Such a structure was created on a graphite plate (3 mm thickness) by ultrashort laser ablation. The morphology and composition (ratio of C-O and C-C bonds) of INW could be controlled by ionization energy (Figure 3l).…”

“…55 Similarly, interconnected nanocarbon web could be applied for in vitro detection and differentiation of HeLa cells and fibroblasts from distinctive SERS band profile of lipids, proteins and DNA/RNA. 9 Non-plasmonic NPs could also serve for SERS imaging. For example, Alizarin Red modified TiO2 NPs were used for cancer cell imaging; 57 alkyne conjugated MoS2 for live cell imaging; cyanine-labeled CuS for cancer tissue imaging.…”

“…Compared to their plasmonic counterparts, the EF of plasmon-free substrates are much lower with values ranging from 10 2 to 10 5 . 8,9 Yet, these materials, based on carbon, silicon, oxides, chalcogenides, etc, could be a low-cost alternative as SERS substrates. In this review, we will focus on this promising class of SERS substrates, based on non-plasmonic materials, introducing the fundamental aspects of chemical enhancement mechanism (CM), the various synthesis methods and categories of materials and their practical applications in biomedical fields (Figure .…”

Optical nanoantenna for beamed and surface‐enhanced Raman spectroscopy

“…Various nanostructured materials are studied extensively as they involve light–matter interaction in small scale where quantum mechanical effects become relevant. [ 62,87–97 ] Achieving smaller gap widths has been a long‐pursued goal in the realization of SERS substrates. Reports, however, indicate that reducing gap width for SERS applications is not always beneficial.…”