Isolating and follow-up characterizing circulating tumor cells (CTCs) is critical but still challenging in diagnosis and treatment of cancers, not only because of their rarity in the blood but highly heterogeneity in the phenotype[1]. Herein, we report an on-chip single cell phenotype profiling strategy based on multiplexed surface enhanced Raman scattering (SERS) signals. CTCs deriving from three different breast cancer cell lines were flowed and trapped by a narrow-gap array in a microfluidic chip. The gap size was designed to efficiently hold up CTCs but allow blood cells to pass through. Then, cocktails of three distinct SERS-labelled aptamer-vectors were flowed into the chip, which are able to specifically recognize three surface biomarkers on breast cancer cells. Due to the phenotypic difference of cellular subgroups, the SERS spectra gathered from each cell lines show distinct patterns in accordance with the expression level of surface biomarkers[2]. Using multivariate analysis method, we analyzed the three surface biomarkers of three breast cancer subtypes with a single cell resolution.

Fig.1 shows the workflow of the SERS-based cell phenotype profiling strategy. Fig.1c displays the distinct typical spectra measured from single captured breast cancer cell that treated by a cocktail of SERS vectors. Owing to the variant biomarkers expression level on the surface of cells, the corresponding SERS signature shows different intensity. We clearly observed the spectral pattern difference among the three cell subpopulations and separate them utilizing multivariate analysis method (Fig.1d).

Physical science is rooted in measurement, but even this simple idea becomes complicated at the nanoscale. For example, how does one actually measure the charge of a single nanoparticle? Traditional electrical methods are limited to micrometer-sized objects, yet nanoparticle charge is a crucial parameter in fields spanning astronomy, optics, biochemistry, environmental engineering, and surface chemistry. In recent years, air pollution has become a severe threat to human health. The main pollution sources, including industrial dusts and chemical colloids suspended in air, are not neutral but charged.

Over the past few years, optical whispering-gallery mode (WGM) microresonators have become valuable tools in sensing applications due to the significantly enhanced light-matter interaction provided by their ultrahigh-Q factors and small mode volumes. So far, by monitoring either the cavity resonant wavelength shift (mode shift) or mode splitting, single nanoparticle binding events have been resolved. However, the sensing signal corresponds to either the size or the permittivity of particles. WGM microcavity based nanoparticle charge measurement remains unstudied.

We propose that by monitoring the transmission spectrum of a high-Q whispering gallery mode resonator, surplus charge at very low electron density can be detected. A single nanoparticle adsorbed to the resonator results in mode splitting of the two initially degenerate whispering gallery modes through backscattering. Because of the modification of nanoparticle conductivity induced by the surplus electrons, both the nanoparticle-WGM coupling strength and the dissipation changes accordingly compared with the case of a neutral nanoparticle. The charge density of the nanoparticle can be inferred by monitoring the mode splitting, the linewidth broadening, or the resonance dip value of the transmission spectrum of the microcavity. Because of the ultranarrow resonance linewidth and small mode volume of the microresonator, measurement of surface and bulk charge with very low charge density is realized.

  A number of attempts have been made for performing digital PCR¹ or isothermal amplifications² for the absolute quantification of nucleic acids using microfluidic technologies. Here, we describe a portable and easy-to-use digital loop-mediated isothermal amplification (dLAMP) system built on our recently reported cross-interface emulsification (XiE) technology³.

  XiE is a simple method which generates monodisperse droplets using vibrating capillaries, which can be easily set up and is user-friendly to those who lack microfabrication facilities. A schematic view of the droplet generation by cross-interface emulsification (XiE) is illustrated in Figure 1. The XiE method can generate size-tunable droplet arrays independent of device design. Thousands of nanoliter droplets can be generated in each well of a 96-well plate, and used for digital nucleic acids quantification based on dLAMP. Moreover, droplet arrays with various sizes can further expend the dynamic range of detection based on multivolume digital analysis.

  We applied this XiE-based dLAMP system in rapid detection of an important infectious pathogens, Mycobacterium bovis (M. bovis), a pathogen which causes bovine tuberculosis (bTB) and human infections. We constructed the mpb70-T1 plasmid which contains unique mpb70 gene of M. bovis⁴ and used it as the standard to investigate the detection limit of dLAMP (Fig. 2). A good linearity between input templates and measured concentration were obtained. Next, we tested the robustness of dLAMP in direct detection M. bovis in real samples. The plasmids with two concentrations (13fg and 130fg) were added in fetal bovine serum (Fig. 3) with or without dilution, and used as samples to perform dLAMP without further treatment. Our results showed that dLAMP is very robust and succeeded in the amplification of mpb70 gene in fetal bovine serum with 2x dilution, and the results were consistent with water control. This result validated that dLAMP can be directly used to analyze complex samples to avoid loss of nucleic acid targets during purification and further reduce the delay in diagnosis.

  In summary, our results shows that the XiE-based dLAMP is highly specific and displays comparable sensitivity to real-time PCR (qPCR) and digital PCR (dPCR)⁵, with reduced detection time of 30 min to 1 hour. Moreover, dLAMP can be used directly for rapid detection of diluted real samples. Therefore, our dLAMP system is especially suitable for environmental and clinical samples with hard-to remove contaminants, and can be widely applied in quantitative and timely diagnosis of infectious diseases.

An LSPR biosensor holds attractive advantages of low-cost, capacity of high integration, requirement of simple optical configuration, surpassing commercial mechanical, or propagating surface plasmon resonance (PSPR) biosensors for construction of miniaturized biomedical devices. Well-designed metal nanostructures with “hot-spots” (the region with intense electromagnetic field, mostly located at sharp nanotips, nanoedges, or nanoslits), possessing superior bulk refractometric and molecular detection sensitivity, are ideal candidates for LSPR biosensors. Therefore, sharp tips in nanostructures play an essential role in improving the performance of LSPR sensor.

Here, we present an overview of our recent work on using a well-ordered plasmonic nanopyramid array with sharp tips for highly-sensitive refractometric and surface enhanced Raman biosensing. Firstly, we introduce a well-ordered Al nanopyramid array (NPA), fabricated by a facile method of elastic soft lithography and subsequent metal deposition. This Al NPA with sharp tips possess high refractometric sensitivity of ~ 820.4 nm/RIU, which even exceeds that of metal nanobranches. Secondly, we characterize the strongly enhanced local electric field at the tip of nanopyramid in comparison to Al flat film (FF), by performing finite difference time domain (FDTD) simulations. Lastly, we apply this plasmonic nanostructure to real-time monitoring the proliferation of Hella cells. The peak positions of the measured transmission spectra is found linear to the culturing time. After 96 hours, the maximal peak shift is ~ 7.2 nm.

Malaria remains one of the most devastating infectious diseases around the globe, infecting 200 million people and resulting in over half a million deaths every year. Increasing resistance by malaria parasites to currently used antimalarials across the developing world requires timely detection and classification so that appropriate drug combinations can be administered before clinical complications arise. Here, we developed a simple, inexpensive and portable image-based cytometer that detects and numerically counts the malaria infected red blood cells (iRBCs) from Giemsa-stained smears. The developed cytometer is able to classify parasitic subpopulations based on the quantification of the area occupied by the parasites within iRBCs and demonstrates high specificity and sensitivity in calculating the parasitemia irrespective of its developmental stage. Moreover, selected antimalarials were tested using our image-based cytometer in comparison to commercial flow cytometer, which demonstrated comparable and matching results with the previously published results. Collectively, these results highlight the possibility to use our portable image-based cytometer as a field-deployable tool for cheap, rapid and accurate malaria diagnosis and antimalarial testing without compromising on the efficiency.

Conventional two-dimensional (2D) monolayer cell cultures lack the three-dimensional (3D) architectures as those of real tissues in vivo. In cancer research, comparing 2D cell cultures with 3D cellular spheroids, the latter have features closer to those of a real tumor, such as cell-cell interaction, molecule responses [1]. Cigarette smoke is a main risk factor for lung cancers because it may participate in lung tumor invasion and metastasis [2]. However, the effect of cigarette smoke in 3D microenvironment of a lung tumor is still unclear. In the present study, we treated 3D cellular spheroids of co-cultured lung cancer cells and fibroblasts with cigarette smoke extract (CSE) to observe the variations of cell viability and invasion ability with light-sheet fluorescence microscopy (LSFM). LSFM is suitable for the observations on cellular spheroids because of its low phototoxicity and 3D imaging capability [3]. Figure 1 shows the LSFM systems used in this work.

We employed a microfluidic culture device to form co-culture cellular spheroids of lung fibroblast MRC-5 and lung cancer cell CL1-0 [4]. The cancer cells and fibroblasts were labelled with different dyes, such that we could employ LSFM to measure the intensity variation of individual types of cells. Figure 2 is the LSFM images of the co-culture spheroids without and with the treatments of CSE. Our experimental data show that CSE reduced the signal of fibroblasts, while that of the cancer cells sustained. It seems that the cancer cells have a higher resistance to the toxicity of CSE. We also verified the invasion ability of co-culture spheroid under the CSE treatment. Figure 3 shows that CSE could enhance the invasion ability of both fibroblasts and lung cancer cells as the spheroid was placed in Matrigel^®.

Previous studies indicated CSE could improve the growth of tumor by reverse Warburg effect through the enhancement of autophagy in the surrounding fibroblasts [5]. We are now analyzing the expressions of specific proteins related to autophagy in the fibroblasts under the treatment of CSE. The preliminary results showed that the CSE treatment increased the expression of LC3B and decreased p62 in fibroblast. These changes in protein expressions indicated the promotion of autophagy. Therefore, we hypothesized that the autophagy of fibroblast was involved in the viability and invasion ability of cancer cells under the CSE treatment. More data will be presented in the Conference.

REFERENCES:

1. Pampaloni, F., E.G. Reynaud, and E.H.K. Stelzer, The third dimension bridges the gap between cell culture and live tissue. Nat. Rev. Mol. Cell Biol., 2007. 8(10): p. 839-845.
2. Wang, Q., et al., Activation of uPAR is required for cigarette smoke extract-induced epithelial-mesenchymal transition in lung epithelial cells. Oncol. Res., 2013. 21(6): p. 295-305.
3. Pampaloni, F., B.J. Chang, and E.H. Stelzer, Light sheet-based fluorescence microscopy (LSFM) for the quantitative imaging of cells and tissues. Cell Tissue Res, 2015. 360(1): p. 129-41.
4. Patra, B., et al., Migration and vascular lumen formation of endothelial cells in cancer cell spheroids of various sizes. Biomicrofluidics, 2014. 8: p. 052109.
5. Salem, A.F., et al., Cigarette smoke metabolically promotes cancer, via autophagy and premature aging in the host stromal microenvironment. Cell Cycle, 2013. 12(5): p. 818-825.

This paper presents recent work on the design and characterization of germanium-on-silicon (Ge-on-Si) waveguides, multimode interferometers, and grating couplers in the 7.5-8.5 mm wavelength range. The development of photonic integrated circuits (PICs) that can operate in the mid-infrared wavelength rage (3-14 mm) is attracting great interest in the field because of the potential to address a broad range of applications related to the on-chip sensing of gases, chemicals, and biological molecules. Ge-on-Si is a very promising material platform for use in the mid-infrared because of the wide transparencies of Si (1.1 to ~8 mm) and Ge (2 to ~16 mm). This work extends its wavelength range of operation up to ~8 mm for the first time. Experimental techniques for characterizing PICs in this challenging range will be discussed, as will prospects for using Ge-on-Si at even longer wavelengths. Finally, the ongoing development of alternative Si and Ge based mid-infrared material platforms will also be discussed.

Ordered fiber bundles (FBs) operating in the mid-infrared spectral region are desirable for the collection and delivery of thermal images in extreme (e.g. under nuclear irradiation) or unfavorable environments (e.g. stray electromagnetic fields, in restricted spaces, etc.). In this paper, high-resolution chalcogenide FBs suitable for transmitting images in the 1.5-6.5 μm and 3-11 μm spectral ranges were prepared and characterized. Recently, The FB was composed of ~200,000 single fibers with a GeAsTeSe glass core of 15 μm in diameter and a polyetherimide (PEI) cladding of 16.8 μm in diameter. The fiber shows good transparency in the 3-12 μm spectral region. The resulting FB presents active area of ~79 % and a crosstalk of ~1 %. Clear thermal images of a human body were obtained using the FB, encouraging that it could be a promising prospect in fiber-optic thermal imaging in medical and industrial applications, in particular for endoscopic thermal imaging.

Optical information devices have been widely studied for various applications in communication, data processing and securities. In the field of advanced photonics, functional materials based on meta-surfaces have huge potentials as they can provide flexible platforms to tune optical functionalities. In this presentation, our recent research progresses on the applications of meta-surfaces to achieve high performance information processing will be discussed to highlight their superior features. These features help to achieve remarkable results, such as the full-color 3D display for naked eyes, ultra-thin and multi-functional integrated multiplexer for optical angular momentum (OAM) signals, and the noise-free planner lens with high numerical aperture. Based on the off-axis illumination method, we develop a novel way to overcome the crosstalk limitation and achieve multi-wavelengths meta-surface devices with a sole type of the plasmonic pixel. For the 3D display, this strategy leads to the remarkable image quality with a signal-to-noise ratio (SNR) 5 times better than the previous designs. For the OAM multiplexer, the number of the information channels can be greatly increased to achieve multi-function integration. For the first time, a full-color meta-holographic image in the 3D space is also experimentally demonstrated. With this method, the usable data capacity can also be greatly improved. Our approach is unique to greatly expand the information capacity of the meta-hologram, which extends broad applications in the data storage, security, and authentication.

A personalized therapy or a precision medicine is one of hot keywords in medical research field. A personalized treatment can be performed only when sufficient information about the disease is provided. Two different studies will be introduced to show how optical spectroscopy and imaging can be utilized to perform personalized treatments. First, a smart automatic cupping therapy system will be introduced. A near-infrared spectroscopic sensor is placed inside of a cup, which acquires the hemodynamic signals during an automatic cupping therapy. Based on the hemodynamic changes from tissue inside the cup, automatic cupping therapy system can induce vacuum or release air to maximize its treatment efficacy. Second, a portable multispectral imaging system was developed to acquire images at 470, 640, 905nm from skin. The measurement of light attenuance at each wavelength can guide low level light therapy (LLLT) system to set its power and time of treatment for each patient. In addition, we applied currently available algorithms to not only white light image but also to multispectral images to provide information of wrinkle and melanin level from skin. From these studies, we show how optical spectroscopy and imaging can play a role in a personalized treatment.