Near IR-plasmon enhanced guided fluorescence and thermal imaging of tissue subsurface target using ICG-labeled gold nanourchin and protein contrast agent: implication of stability.

A dual-function nanocomposite agent (NCA) was prepared for deep tissue fluorescence and thermal imaging. The results showed that a combination of some agents such as gold nanourchins (GNU) and indocyanine green (ICG) can have spectral overlapping and hence some peak broadening. Despite 83% and 92% loss of NCA fluorescence after tissue layers L1 and L2, respectively, there was sufficient signal detected for imaging the target buried under the tissue. No fluorescence was detected after L3. A significant contribution was made by GNU for both the fluorescence signal due to the plasmon-enhanced fluorescence (PEF) effect and the thermal heating because of local surface plasmon resonance (LSPR) due to its sharp tips. In the first case, PEF occurred within the first 40 s then followed by a gradual quenching by 23% in 4 min and 72% in the following 6 min. During the second quenching time, the emission signal was blue shifted by 10 nm. Of the three samples, sample 2 (S2) indicated the highest temperature rise ≈ 60 °C in 50 s; sample 3 (S3) produced the lowest temperature of ≈ 33 °C in 250 s after the first layer, thus showing BSA acting as a heat sink. Both the heating and cooling time are determined by the thermal properties of the material such as conductivity and diffusivity. Finally, despite the advantages of PEF, the photostability and quenching rate of a dye molecule must be considered in a dynamic detection monitoring system to account and compensate for the effect of contrast agent quality variation.

Non-invasive optical characterization and detection of CA 15-3 breast cancer biomarker in blood serum using monoclonal antibody-conjugated gold nanourchin and surface-enhanced Raman scattering.

A proof-of-concept of colloidal surface-enhanced Raman scattering (SERS) substrate for rapid selective detection of overexpressed CA 15-3 biomarker in breast cancer serum (BCS) is suggested using PEGylated gold nanourchins (GNUs) conjugated with anti-CA 15-3 monoclonal antibody (mAb). UV-vis spectroscopy provided conformational information about mAb where the initial aromatic amino acid peak was red-shifted from 271 to 291 nm. The fluorescence peak of tyrosine in mAb was reduced by ≈ 77%, and red-shifted by ≈ 3 nm after incubation in BCS. Fourier transform near-infrared spectroscopy and SERS were used to study the composition and the molecular structure of the mAb and BCS. Some of the most dominant Raman shifts after GNU-PEG-mAb interaction with BCS are 498, 736, 818, 1397, 1484, 2028, 2271, and 3227 cm-1 mainly corresponding to C-N-C in amines, vibrational modes of amino acids, C-H out-of-plane bend, C-O stretching carboxylic acid, the vibrational mode in phospholipids, NH3+ amine salt, C≡N stretching in nitriles, and O-H stretching. The intensity of SERS signals varied per trial due to the statistical behavior of GNU in BCS, agglomeration, laser power, and the heating effect. Despite very small amount of plasmonic heating, the result of the ANOVA test demonstrated that under our experimental conditions, the heating effect on signal variation is negligible and that the differences in the laser power are insignificant for all SERS observations (p > 0.6); thus, other parameters are responsible. The absorbance of mAb-conjugated GNU was decreased after five minutes of irradiation at 8 mW in the BCS.

Dynamic characterization of indocyanine green-assisted dental caries ablation with continuous diode laser using thermal imaging and fluorescence spectroscopy.

We describe the time-resolved thermal changes in indocyanine green (ICG)-assisted diode laser ablation of dental caries as a potential technique for painless treatment based on the selective photoabsorption and controlled photothermal ablation. Static ablation mode produced a higher temperature rise compared with scanning mode due to localized accumulation of heat. A temperature rise between 45-80 and 70-95 °C was obtained after 20 s that corresponded to 29 and 80 W cm-2, respectively. The temperature of the tooth surface increased by irradiation time, and it behaved linearly up to 70 °C at 29 and 80 W cm-2. A maximum ablation per area of about 0.3 and 0.45 mg cm-2 was achieved after 80 s exposure at 29 and 80 W cm-2, respectively. A statistically significant difference is observed in mean carious teeth weight at various exposure times between low and high irradiances. A thermal penetration depth of 0.8-9 mm is determined for 1-100 s of exposure time. The IR thermal imaging of ICG temperature as a function of exposure time showed a linear increase for 60 s beyond which it deviated. The laser-induced fluorescence spectroscopy indicated that the ICG quality can be altered during the course of irradiation, which in our case, it corresponded to ≈ 78% loss of signal within 23 min of exposure. The caries removal experiment was performed within 100 s corresponding to ≈ 7% loss. We believe that the application of the above-combined technique can be utilized as a monitoring device to control the ablation interaction process.

Simultaneous dual-wavelength photoacoustic radar imaging using waveform engineering with mismatched frequency modulated excitation.

The spectroscopic imaging capability of photoacoustics (PA) without the depth limitations of optical methods offers a major advantage in preclinical and clinical applications. Consecutive PA measurements with properly chosen wavelengths allow composition related information about blood or tissue. In this work, we propose and experimentally introduce modulation waveform engineering through the use of mismatched (uncorrelated or weakly correlated) linear frequency modulated signals for PA characterization and imaging. The feasibility of the method was tested on oxygen saturated hemoglobin and deoxygenated hemoglobin in vitro in a blood circulating rig. The method was also employed for in vivo imaging of a neck carcinoma tumor grown in a mouse thigh. The proposed method can increase the accuracy and speed of functional imaging by simultaneous PA probing with two wavelengths using portable laser-diode based PA imaging systems.

Nanoshell-mediated targeted photothermal therapy of HER2 human breast cancer cells using pulsed and continuous wave lasers: an in vitro study.

In this study, we report the apoptosis induction in HER2 overexpressed breast cancer cells using pulsed, continuous wave lasers and polyvinylpyrrolidone (PVP)-stabilized magneto-plasmonic nanoshells (PVP-MPNS) delivered by immunoliposomes. The immunoliposomes containing PVP-MPNS were fabricated and characterized. Heating efficiency of the synthesized nanostructures was calculated. The effect of functionalization on cellular uptake of nanoparticles was assessed using two cell lines of BT-474 and Calu-6. The best uptake result was achieved by functionalized liposome (MPNS-LAb) and BT-474. Also, the interaction of 514 nm argon (Ar) and Nd/YAG second harmonic 532-nm lasers with nanoparticles was investigated based on the temperature rise of the nanoshell suspension and the release value of 5(6)-carboxyfluorescein (CF) from CF/MPNS-loaded liposomes. The temperature increase of the suspensions after ten consecutive pulses of 532 nm and 5 min of irradiation by Ar laser were measured approximately 2 and 12 °C, respectively. The irradiation of CF/MPNS-loaded liposomes by Ar laser for 3 min resulted in 24.3 % release of CF, and in the case of 532 nm laser, the release was laser energy dependent. Furthermore, the comparison of CF release showed a higher efficiency for the Ar laser than by direct heating of nanoshell suspension using circulating water. The percentage of cell apoptosis after irradiation by Ar and 532 nm lasers were 44.6 and 42.6 %, respectively. The obtained results suggest that controlling the NP-laser interaction using optical properties of nanoshells and the laser parameters can be used to develop a new cancer therapy modality via targeted nanoshell and drug delivery.

Reflective FT-NIR and SERS studies of HER-II breast cancer biomarker using plasmonic-active nanostructured thin film immobilized oriented antibody.

We describe the fabrication of plasmonic-active nanostructured thin film substrate as a label-free surface-enhanced Raman scattering (SERS)-based biosensor immobilized covalently with monoclonal HER-II antibody (mAb) to detect overexpressed HER-II as a biomarker in breast cancer serum (BCS). Oriented conjugation of mAb via hydrazone linkage to provide higher mAb accessibility was characterized by UV-vis and reflective Fourier transform near-infrared (FT-NIR) spectroscopic techniques. The interaction of BCS with mAb was studied by FT-NIR and nonresonant SERS at 637 nm. The results showed detection of glycoprotein content at different laser powers including a rise in amino acid and glycan content with varying results at higher power. With nonresonant SERS we observed nonlinear behavior of peak intensity. Analysis of variance was implemented to determine the effect of laser power which was found not to be a contributing factor. However, at the nanoscale, factors including the heating effect and aggregation of molecules can contribute to the nonlinearity of peak intensity.

An in-vitro investigation of skin tissue soldering using gold nanoshells and diode laser.

Gold-coated silica core nanoparticles have an optical response dictated by the plasmon resonance (PR). The wavelength at which the resonance occurs depends on the core and shell size, allowing nanoshells to be tailored for particular applications. The purpose of this study is to synthesize and use different concentrations of gold nanoshells as exogenous material for in-vitro skin tissue soldering and also to examine the effect of laser-soldering parameters on the properties of repaired skin. Two mixtures of albumin solder and different concentrations of gold nanoshells were prepared. A full-thickness incision of 2 × 20 mm(2) was made on the surface and after addition of mixtures it was irradiated by an 810-nm diode laser at different power densities. The changes of tensile strength σ(t) due to temperature rise, number of scan (N(s)), and scan velocity (V(s)) were investigated. The results showed at constant laser power density (I), σ(t) of repaired incisions increases by increasing the concentration of gold nanoshells, N(s) and decreasing V(s). It is therefore important to consider the trade-off between the scan velocity and the skin temperature for achieving an optimum operating condition. In our case, this corresponds to σ(t) = 1,610 g/cm(2) at I ∼ 60 Wcm(-2), T ∼ 65°C, Ns = 10 and Vs = 0.2 mms(-1).

Surface morphology characterization of laser-induced titanium implants: lesson to enhance osseointegration process.

The surface properties of implant are responsible to provide mechanical stability by creating an intimate bond between the bone and implant; hence, play a major role on osseointegration process. The current study was aimed to measure surface characteristics of titanium modified by a pulsed Nd:YAG laser. The results of this study revealed an optimum density of laser energy (140 Jcm-2), at which improvement of osteointegration process was seen. Significant differences were found between arithmetical mean height (Ra), root mean square deviation (Rq) and texture orientation, all were lower for 140 Jcm-2 samples compared to untreated one. Also it was identified that the surface segments were more uniformly distributed with a more Gaussian distribution for treated samples at 140 Jcm-2. The distribution of texture orientation at high laser density (250 and 300 Jcm-2) were approximately similar to untreated sample. The skewness index that indicates how peaks and valleys are distributed throughout the surface showed a positive value for laser treated samples, compared to untreated one. The surface characterization revealed that Kurtosis index, which tells us how high or flat the surface profile is, for treated sample at 140 Jcm-2 was marginally close to 3 indicating flat peaks and valleys in the surface profile.

Evaluation of cell viability and T2 relaxivity of fluorescein conjugated SPION-PAMAM third generation nanodendrimers for bioimaging.

This study has investigated the possibility of using fluorescent dendronized magnetic nanoparticles (FDMNPs) for potential applications in drug delivery and imaging. FDMNPs were first synthesized, characterized and then the effect of Polyamidoamine (PAMAM) dendrimer functionalization and fluorescein isothiocyanate (FITC) conjugation on biocompatibility of superparamagnetic iron oxide nanoparticles (SPIONs) was evaluated. The nanostructures' cytotoxicity tests were performed at different concentrations from 10 to 500 µg/mL using MCF-7 and L929 cell lines. IC50 in MTT assay were 139.22 and 201.88 µg/mL for DMNP incubated L929 and MCF-7 cell lines respectively, whereas the cell viability for FDMNPs did not decrease to 50%. The results showed that FITC conjugation diminishes the toxicity of dendronized magnetic nanoparticles (DMNPs) mainly due to the reduction of surface charge. DMNP appears to be cytotoxic at the concentration levels being used for both cell lines. On the contrary, FDMNPs showed more biocompatibility and cell viability of MCF-7 and L929 cell lines at all concentrations. The fluorescence microscopy of FDMNPs incubated with MCF-7 cells showed a successful localization of cells indicating their ability for applications such as a magnetic fluorescent probe in cell studies and imaging purposes. T2 relaxivity measurements demonstrated the applicability of the synthesized nanostructures as the contrast agents in tissue differential assessment by altering their relaxation times. In our case, the r2 relaxivity of FDMNPs was measured as 103.67 mM(-1)S(-1).

Frequency-domain photothermoacoustic and ultrasonic imaging of blood and opto-thermal effects of plasmonic nanoparticle concentrations.

We describe the use of combined ultrasonic imaging (USI) and photoacoustic radar imaging (PARI) with linear chirp laser modulation to provide visualization of blood with and without the use of gold nanoparticles. A blood vessel simulating sample (S1) containing pure sheep blood was shown to be an optically weak absorbing medium which satisfies thermal but not acoustic confinement. On the contrary, the blood-gold combinations (S2) using 10% and S3 (20%) Au concentrations behaved as optically strongly absorbing media. A heating efficiency of 0.54 to 8.60×10(3) K cm(2) (-1) was determined for Au NPs. The optimal optical power modulation spectral density was determined to be in the range of 0.5 to 0.8 MHz and 0.3 to 1.0 MHz for USI and PARI, respectively. USI produced a better structural image while PARI produced a better functional image of the simulated blood vessel in the order of S2>S3>S1 due to enhanced signal-to-noise ratio. Two-dimensional images of the simulated blood vessel were also obtained. In summary, the PA signal does not increase linearly with Au NP concentration and the change of blood osmolarity due to temperature increase can cause thermo-hemolysis of red blood cells which in turn degrades the PA signal and thus the blood imaging quality. On the other hand, USI produced the best structural image, S4, due to the strong US reflection response from Au NPs and its insensitivity to the presence of blood.

Simulation and experimental results of optical and thermal modeling of gold nanoshells.

This paper proposes a generalized method for optical and thermal modeling of synthesized magneto-optical nanoshells (MNSs) for biomedical applications. Superparamagnetic magnetite nanoparticles with diameter of 9.5 ± 1.4 nm are fabricated using co-precipitation method and subsequently covered by a thin layer of gold to obtain 15.8 ± 3.5 nm MNSs. In this paper, simulations and detailed analysis are carried out for different nanoshell geometry to achieve a maximum heat power. Structural, magnetic and optical properties of MNSs are assessed using vibrating sample magnetometer (VSM), X-ray diffraction (XRD), UV-VIS spectrophotometer, dynamic light scattering (DLS), and transmission electron microscope (TEM). Magnetic saturation of synthesized magnetite nanoparticles are reduced from 46.94 to 11.98 emu/g after coating with gold. The performance of the proposed optical-thermal modeling technique is verified by simulation and experimental results.

Enhanced laser tissue soldering using indocyanine green chromophore and gold nanoshells combination.

Gold nanoshells (GNs) are new materials that have an optical response dictated by the plasmon resonance. The wavelength at which the resonance occurs depends on the core and shell sizes. The purposes of this study were to use the combination of indocyanine green (ICG) and different concentration of gold nanoshells for skin tissue soldering and also to examine the effect of laser soldering parameters on the properties of repaired skin. Two mixtures of albumin solder and different combinations of ICG and gold nanoshells were prepared. A full thickness incision of 2 × 20 mm(2) was made on the surface and after addition of mixtures it was irradiated by an 810 nm diode laser at different power densities. The changes of tensile strength (σ(t)) due to temperature rise, number of scan (Ns), and scan velocity (Vs) were investigated. The results showed at constant laser power density (I), σ(t) of repaired incisions increases by increasing the concentration of gold nanoshells in solder, Ns, and decreasing Vs. It was demonstrated that laser soldering using combination of ICG + GNs could be practical provided the optothermal properties of the tissue are carefully optimized. Also, the tensile strength of soldered skin is higher than skins that soldered with only ICG or GNs. In our case, this corresponds to σ(t) = 1800 g cm(-2) at I ∼ 47 Wcm(-2), T ∼ 85 [ordinal indicator, masculine]C, Ns = 10, and Vs = 0.3 mms(-1).

Dynamic study of PLGA/CS nanoparticles delivery containing drug model into phantom tissue using CO2 laser for clinical applications.

In this study, cationic nanoparticles (NPs) were prepared by coating chitosan (CS) on the surface of PLGA NPs. To our knowledge most of the work in the field of drug delivery systems using lasers has been performed using short pulses with micron and submicron durations. We carried out an experiment using superlong PLS-R (10 ms) and CW CO2 laser modes on simulated drug-biogelatin model where drug was encapsulated by PLGA/CS NPs. Maximum depth of drug containing cavitation was achieved faster at higher powers and shorter irradiation time in CWC mode. We believe that the main mechanism at work with superlong pulses is both photothermal due to vaporization and photomechanical due to photophoresis and cavitation collapse. In the case of CW, however, it is purely photothermal. Thus, drug molecules can be transported into tissue bulk by thermal waves which can be described by the Fick's law in 3-D model for a given cavity geometry and the mechanical waves, unlike only by pure photomechanical waves (i.e. photoacoustically) as with short pulses. Therefore, our studies could offer an alternative for currently existing method for drug delivery.