pH-Sensitive nanodiamond co-delivery of retinal and doxorubicin boosts breast cancer chemotherapy.

Herein for the first time we take the advantage of nanodiamonds (NDs) to covalently immobilize all-trans retinal (NPA) by an imine bond, allowing pH-mediated drug release. DOX is then physically adsorbed onto NPA to form an NPA@D co-loaded double drug in the sodium citrate medium, which is also susceptible to pH-triggered DOX dissociation. The cytotoxicity results showed that NPA@D could markedly inhibit the growth of DOX-sensitive MCF-7 cells in a synergetic way compared to the NP@D system of single-loaded DOX, while NPA basically showed no cytotoxicity and weak inhibition of migration. In addition, NPA@D can overcome the drug resistance of MCF-7/ADR cells, indicating that this nanodrug could evade the pumping of DOX by drug-resistant cells, but free DOX is nearly ineffective against these cells. More importantly, the fluorescence imaging of tumor-bearing mice in vivo and ex vivo demonstrated that the NPA@D was mainly accumulated in the tumor site rather than any other organ by intraperitoneal injection after 24 h, in which the fluorescence intensity of NPA@D was 19 times that of the free DOX, suggesting that a far reduced off-target effect and side effects would be expected. Therefore, this work presents a new paradigm for improving chemotherapy and reversing drug resistance using the ND platform for co-delivery of DOX and ATR.

A nanodiamond chemotherapeutic folate receptor-targeting prodrug with triggerable drug release.

Cancer chemotherapy is often accompanied by severe off-target effects that both damage quality of life and can decrease therapeutic compliance. This could be minimized through selective delivery of cytotoxic agents directly to the cancer cells. This would decrease the drug dose, consequently minimizing side effects and cost. With this goal in mind, a dual-gated folate-functionalized nanodiamond drug delivery system (NPFSSD) for doxorubicin with activatable fluorescence and cytotoxicity has been prepared. Both the cytotoxic activity and the fluorescence of doxorubicin (DOX) are quenched when it is covalently immobilized on the nanodiamond. The NPFSSD is preferentially uptaken by cancer cells overexpressing the folate receptor. Then, once inside a cell, the drug is preferentially released within tumor cells due to their high levels of endogenous of glutathione, required for releasing DOX through cleavage of a disulfide linker. Interestingly, once free DOX is loaded onto the nanodiamond, it can also evade resistance mechanisms that use protein pumps to remove drugs from the cytoplasm. This nanodrug, used in an in vivo model with local injection of drugs, effectively inhibits tumor growth with fewer side effects than direct injection of free DOX, providing a potentially powerful platform to improve therapeutic outcomes.

Synchronous measurement method of a multi-angle scattered light field.

A synchronous multi-angle scattered light field measurement system is constructed in this study to overcome issues with current systems in the field of multi-angle remote sensing. A mathematical model of the scattered light field measurement was established. An off-axis catadioptric optical system was designed to satisfy hemispheric spatial scattered light field measurements in a zenith angle range of 68°. The off-axis calibration model was established, and the spatial relationship was calibrated. The measurement accuracy was calibrated via an integrating sphere light source, and the maximum measurement relative error was -3.71%. The scattered light field of the reference diffuse reflective target plate Labsphere Permaflect-50 and 304 stainless steel was simulated under an incident light irradiation range within the zenith angle of -23.5∘ to +23.5∘, and synchronous measurement of the multi-angle scattered light field of the sample was realized. The measurement system could provide technical support for building the complex model of multi-angle reflection/radiation from the earth's surface, multi-angle sensor radiation calibration, and improvement of the physical parameter inversion accuracy of observation targets.

Research on spectral reconstruction algorithm for snapshot microlens array micro-hyperspectral imaging system.

Snapshot microlens array microscopic hyperspectral imaging systems do not require a scanning process and obtain (x,y,λ) three-dimensional data cubes in one shot. Currently, the three-dimensional spectra image data are interleaved on a charge-coupled device detector, which increases subsequent data processing difficulty. The optical design software cannot simulate actual engineering installation and adjustment results accurately and the tracking results cannot guide precise rapid online calibration of the snapshot microlens array microscopic hyperspectral imaging system. To solve these problems, we propose an accurate spectral image reconstruction model based on optical tracing, derive spatial dispersion equations for the prisms and gratings, establish an algorithm model for the correspondence between the microlens array's surface dispersion spectral distribution and its imaging position, and propose a three-dimensional spectral image reconstruction algorithm. Experimental results show that this algorithm's actual spectral calibration error is better than 0.2 nm. This meets the image processing requirements of snapshot microlens array microscopic hyperspectral systems.

Backscattering Raman spectroscopy using multi-grating spatial heterodyne Raman spectrometer.

Spatial heterodyne Raman spectrometry (SHRS) is a spectral analysis technique used to study material structures and compositions. We propose a multi-grating SHRS system that uses a multi-grating module rather than the single grating used to terminate each arm in traditional spatial heterodyne spectrometry (SHS). The proposed system not only retains the advantages of traditional SHS but also resolves the mutual limitation between system spectral range and resolution. The increased spectral range and resolution that can be achieved in detection are dependent on the number of sub-gratings used in the module. A verification system was built using 130 gr/mm and 150 gr/mm sub-gratings and calibrated. Under different experimental conditions (including laser power, integration time, container material and thickness, pure and mixed samples, and standoff experiments), the backscattered Raman spectra of different types of targets (including organic solutions, inorganic powders, and minerals) were tested. The multi-grating SHRS shows good performance for broad spectral range and high-resolution Raman detection.

Optical design of a prism-grating-based lenslet array integral field spectrometer.

The optics for an integral field spectrometer based on a lenslet array is described. The principle behind the integral field spectroscopy of this system is introduced and partial modeling of the structure of the system is developed. A hybrid design method from physical optics and geometrical optics is used to design the system. Because the functions of the optical system before and after the lenslet array are different, the telephoto system and the spectrograph need to be separated. The optical system was then optimized using a combination design. This method is confirmed by simulation and comparison results and can be used in the design of other lenslet array integral field spectrometers.

Continuous background correction using effective points selected in third-order minima segments in low-cost laser-induced breakdown spectroscopy without intensified CCD.

This work presents a method that can automatically estimate and remove varying continuous background emission for low-cost laser-induced breakdown spectroscopy (LIBS) without intensified CCD. The algorithm finds all third-order minima points in spectra and uses these points to partition the spectra into multiple subintervals. The mean value is then used as a threshold to select the effective points for the second-order minima in each subinterval. Finally, a linear interpolation method is used to realize extension of these effective points and complete fitting of the background using polynomials. Using simulated and real LIBS spectra with different complexities examine the validity of proposed algorithm. Additionally, five elements of five standard cast iron alloy samples are calibrated and improved very well after background removal. The results successfully prove the validity of the background correction algorithm.

Design and analysis of a worm gear turntable off-axis assembly method in a three-grating monochromator.

To solve the problem where the actual grating aperture decreases with an increasing scanning angle during the scanning of a three-grating monochromator, we propose an off-axis assembly method for the worm gear turntable that makes it possible to suppress this aperture reduction. We simulated and compared the traditional assembly method with the off-axis assembly method in the three-grating monochromator. Results show that the actual grating aperture can be improved by the off-axis assembly method. In fact, for any one of the three gratings, when the monochromator outputs the longest wavelength in the corresponding wavelength band, the actual grating aperture increases by 45.93%. Over the entire monochromator output band, the actual grating aperture increased by an average of 32.56% and can thus improve the monochromator's output energy. Improvement of the actual grating aperture can also reduce the stray light intensity in the monochromator and improve its output signal-to-noise ratio.

Optical design of a short-wave infrared prism-grating imaging spectrometer.

A miniaturized portable short-wave infrared imaging spectroscopy optical system is designed based on a prism-grating dispersion module. We established a prism-grating model to calculate the optimal combination of prism and grating parameters to balance spectral smile over the entire band. The design method for the telescopic system and spectroscopic system combines independent design with integrated optimization. The system's spectral smile and spectral keystone are less than 15 µm and less than half a pixel, respectively. The total optical system length is 230 mm, which meets the miniaturization requirements for airborne systems. The system's spatial resolution is 1 mrad, and its average spectral resolution is 6.2 nm. The system offers the advantages of large relative aperture, excellent imaging quality, reduced spectral smile, and spectral keystone, miniaturization, and portability.

Method for measurement of eccentricity and tilt of lenslet array integral field spectrometer.

This paper proposes a more accurate eccentricity and tilt measurement method based on Young's interference experiment. The basic principle of the method is introduced first before the method is simulated. Then the results are obtained when a to-be-adjusted focusing lens with eccentricity and tilt is simulated. The optical sensitivity also is obtained from these simulation results, and the expression for the change in optical path length caused by eccentricity and tilt is analyzed. Use of this method to detect eccentricity and tilt and assist in adjustment of the system allows the instrument to achieve higher accuracy and thus obtain improved imaging quality and spectral resolution.

High-accuracy spectral reduction algorithm for the échelle spectrometer.

A spectral reduction algorithm for an échelle spectrometer with spherical mirrors that builds a one-to-one correspondence between the wavelength and pixel position is proposed. The algorithm accuracy is improved by calculating the offset distance of the principal ray from the center of the image plane in the two-dimensional vertical direction and compensating the spectral line bending from the reflecting prism. The simulation and experimental results verify that the maximum deviation of the entire image plane is less than one pixel. This algorithm ensures that the wavelengths calculated from spectrograms have a high spectral resolution, meaning the precision from the spectral analysis reaches engineering standards of practice.

[Research on Small-Type and High-Spectral-Resolution Grating Monochromator].

Monochromator is the necessary equipment for spectral imager to calibrate the spectrum continuously. In order to calibrate the hyperspectral imaging spectrometer continuously, a small-type and high-spectral-resolution grating monochromator is designed. The grating monochromator with horizontal Czerny-Turner structure is designed with high-spectral-resolution as a starting point, and the design idea is discussed in detail from choosing the grating, calculating the focal length, the sizes of entrance slit and exit slit, among others. Using this method, the necessary structure parameters are determined, and the impact of the necessary structure parameters for spectral resolution and volume is given. According to the optical characteristics of the grating monochromator, the mechanical structures of the instrument are designed for small and handy from the components of the entrance slit, the collimator lens and imaging objective lens, the scanning structures, the fuselage and so on. The relationship of the sine mechanism parameters for output wavelength and wavelength scanning accuracy is given. The design and adjustment of the instrument are completed. The visible spectrums of mercury lamp are used as calibration lines, and the calibration curve is acquired by using least square method. This paper gives a method that combining the limit error of the step number and the calibration curve to evaluate the wavelength repeatability and wavelength precision. The datum of experiment shows that the spectral resolution of the instrument is better than 0.1 nm in the wavelength band from 400 to 800 nm. Simultaneously the wave-length repeatability reach to ± 0.96 6 nm and the precision reach to ± 0.096 9 nm.

[Study on the Design of Prism Hyperspectral Imaging System Based on Off-Axis Two-Mirror Littrow Configuration].

In order to meet the requirements of high spectral resolution and high image quality on the hyperspectral imaging system, and to meet the new demands of miniaturization, light weight, and high optical efficiency in practical applications, a prism known as hyperspectral imaging system based on Littrow configuration is designed. The use of off-axis two-mirror Littrow configuration is to reduce the size of the optical system and provide a collimated beam for the plane prisms. To avoid the optical path interference, the macro programming optimization is applied. The application of two correct lens and aspheric mirrors can correct the spectral smile and the keystone of the hyperspectral imaging system. It is indicated that the distortion is less than 2.1 µm and the spectral bend is less than 1.3 µm, both are controlled within 18% pixel. The analytical results indicate that the MTF in the visible-near infrared(VNIR) spectral region from 400 to 1 080 nm is above 0.9 while spectrum resolution is about 1.6～5.0 nm, the spectral transmittance more than 51.5%. The results show that the system has high transmittance and image quality within the whole spectral range.

[Optimal Design of Light Folding Imaging Spectrometer Based on Dyson Concentric System].

Concave grating spectrometer based on Dyson concentric optical system has advantages of low aberration, large aperture and compact structure. The object plane and image plane of concentric spectrometer subsystem must be reunited into one plane while the distance between the object point and image point is relatively small. Thus it is difficult to satisfy this requirement for the existing focal plane of detection technology and assembly technology. In order to solve the assembly problem of the object and detector, the traditional Dyson concentric spectrometer was improved by introducing the off-axis mirror to shift the image light beam. The results show that the object plane and image plane of the improved system are separated successfully by the beam folding, and the aberration at all wavelengths is more rational distribution.

[Algorithm for Background Removal in Spectral Image of Echelle Spectrometer].

Echelle spectrometer gets full spectrum by transient direct reading because of the characteristic of cross-dispersion. The two-dimension spectra received by flat-plane detector needs to be reduced to one-dimension spectra so that the effective wavelength can be detected. Because of huge original data and few effective data, background removal plays an important role of decreasing the amount of data and improving data processing speed. The two-dimension spectrum of echelle spectrometer is analyzed and a suitable background removal algorithms is came up. The edge detection method is applied to diffuse spot detection. Selecting appropriate operator to convolute original image to get edge image and calculating global threshold to segment edge image which can be used to map original image to get the background removed image. Two-dimensional spectral images based on different elements at different integration time are used to judge the effect of different background removal algorithm and different operator are analyzed to figure out their effect of speed and accuracy for algorithm. Experimental result shows that the algorithm came up by this letter is better for image background removal than the others. The background removed image can be used in spectrum reductionand the speed of data processing is notable promoted.

[An Effective Wavelength Detection Method Based on Echelle Spectra Reduction].

Echelle spectrometer with high dispersion, high resolution, wide spectral coverage, full spectrum transient direct-reading and many other advantages, is one of the representative of the advanced spectrometer. In the commercialization trend of echelle spectrometer, the method of two-dimension spectra image processing is becoming more and more important. Currently, centroid extraction algorithm often be used first to detect the centroid position of effective facula and then combined with echelle spectrum reduction method to detect the effective wavelength, but this method is more difficult to achieve the desired requirements. To improve the speed, accuracy and the ability of imaging error correction during detecting the effective wavelength, an effective wavelength detection method based on spectra reduction is coming up. At the beginning, the two-dimension spectra will be converted to a one-dimension image using echelle spectra reduction method instead of finding centroid of effective facula. And then by setting appropriate threshold the one-dimension image is easy to be dealing with than the two-dimension spectra image and all of the pixel points stand for effective wavelength can be detected at one time. Based on this new idea, the speed and accuracy of image processing have been improved, at the same time a range of imaging errors can be compensated. Using the echelle spectrograph make a test applying this algorithm for data processing to check whether this method is fit for the spectra image processing or not. Choosing a standard mercury lamp as a light source during the test because the standard mercury lamp have a number of known characteristic lines which can be used to examine the accuracy of wavelength detection. According to experimental result, this method not only increase operation speed but improve accuracy of wavelength detection, also the imaging error lower than 0.05 mm (two pixel) can be corrected, and the wavelength accuracy would up to 0.02 nm which can satisfy the requirements of echelle spectrograph for image processing.

[Full-field and automatic methodology of spectral calibration for PGP imaging spectrometer].

In order to analyze spectral data quantitatively which is obtained by prism-grating-prism imaging spectrometer, spectral calibration is required in order to determine spectral characteristics of PGP imaging spectrometer, such as the center wavelength of every spectral channel, spectral resolution and spectral bending. A spectral calibration system of full field based on collimated monochromatic light method is designed. Spherical mirror is used to provide collimated light, and a freely sliding and rotating folding mirror is adopted to change the angle of incident light in order to realize full field and automatic calibration of imaging spectrometer. Experiments of spectral calibration have been done for PGP imaging spectrometer to obtain parameters of spectral performance, and accuracy analysis combined with the structural features of the entire spectral calibration system have been done. Analysis results indicate that spectral calibration accuracy of the calibration system reaches 0.1 nm, and the bandwidth accuracy reaches 1.3%. The calibration system has merits of small size, better commonality, high precision and so on, and because of adopting the control of automation, the additional errors which are caused by human are avoided. The calibration system can be used for spectral calibration of other imaging spectrometers whose structures are similar to PGP.

[Model design and stray light suppression technology of stray-light testing equipment for plane grating].

Grating scatter is an important performance index for plane grating, and its measurement is a difficult problem for grating research field. In order to achieve stray-light of the instrument itself to be less than 10(-8) so that the grating scatter can be accurately measured, stray light in diffraction grating monochromators has been studied and an opto-mechanical model of measure instrument for plane grating is designed, which works in parallel light environment and based on the scalar diffraction theory and classical Fresnel-Kirchhoff diffraction theory. Main pathway of the instrumentation's stray light is calculated and analyzed by the simulation of stray-light testing equipment with ASAP software. Accordingly, four stray-light suppression structures including blocking rings, vanes, aperture stops and light traps are proposed to reduce instrument's scattered light and grating's multiple diffraction. Finally, contrast analysis of the instrumentation's stray light is made before and after adding stray-light suppression structures. Simulation and analysis results show that the max of instrument's stray light reduces from more than 10(-6) to less than 10(-8) after adding stray-light suppression structures and has met the stray-light testing equipment's design requirements whose goal is to realize accurate measurement greater than or equal to 10(-7) for grating scatter with grating's groove density changing from 300 to 3 600 gr x mm(-1). The research methods and results above will provide a theoretical basis for the research and development of the stray-light testing equipment for plane grating.

[Research on influencing factors and compensation method of testing results for concave gratings diffraction efficiency].

The present paper aimed at the question that the beam cross-section changes according to the rotation of concave grating during the measuring process, and the appropriate supplement to the principle of the program was done. The appropriate supplement to the principle lay the foundation for the derivation of the beam cross-section k(theta), and the whole analytical expression of changes factor of the beam cross-section k (theta) for concave grating was derived. Because of the relationship between the theoretical values and the factors which affect the diffraction efficiency measuring accuracy was nonlinear, the quadratic nonlinear regression analysis was introduced and the compensating formula was established. The results show further correction to diffraction efficiency measurements for concave grating, the range of differences between the compensated values and the theoretical values was reduced from +/- 2.5% to less than +/- 0.3%, compared with the linear regression analysis, and the quadratic nonlinear regression analysis significantly reduces the variation between the compensated values and the theoretical values, which further ensures the accurate measurement of the diffraction efficiency for concave gratings. The compensating process is embedded in the measurement program; this method is strongly real-time, which can satisfy the requirements of simple operation, testing speediness and preciseness.

Use of metal-enhanced fluorescence spectroscopy for detection of polycyclic aromatic hydrocarbons in diesel oil emulsions in artificial seawater.

In this study, we employed the metal-enhanced fluorescence (MEF) method for the detection of polycyclic aromatic hydrocarbons (PAHs) in diesel oil emulsions in artificial seawater. Silver nanoparticles with an average diameter of 80 nm were immobilized onto silanized quartz as MEF substrates. Excited by illumination at 355 nm, a 4.6-fold increase in the fluorescence signals of PAHs was recorded when MEF substrates were used. The finite-difference time-domain (FDTD) method was used to provide mechanistic insights into the fluorescence enhancement. Monitoring water pollution has environmental significance and MEF spectroscopy is finding direct applications in this field.