Multiple Release Kinetics of Targeted Drug from Gold Nanorod Embedded Polyelectrolyte Conjugates Induced by Near-Infrared Laser Irradiation

Enhanced anti-cancer potency of sustainably synthesized anisotropic silver nanoparticles as compared with L-asparaginase

Acute lymphoblastic leukemia (ALL), a hematologic cancer that involves the production of abnormal lymphoid precursor cells, primarily affects children aged 2 to 10 years. The bacterial enzyme L-asparaginase produced from Escherichia coli is utilised as first-line therapy, despite the fact that 30 % of patients have a treatment-limiting hypersensitivity reaction. The current study elucidates the biosynthesis of extremely stable, water-dispersible, anisotropic silver nanoparticles (ANI Ag NPs) at room temperature and investigation of its anti-tumor potency in comparison to L-asparaginase. The optical, morphological, compositional, and structural properties of synthesized nanoparticles were evaluated using UV-Vis-NIR spectroscopy, Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy, and X-ray Diffractometer. The UV-Vis-NIR spectra revealed the typical Surface Plasmon Resonance (SPR) at 423 nm along with additional NIR absorption at 962 nm and 1153 nm, while TEM images show different shapes and sizes of Ag nanoparticles ranging from 6.81 nm to 46 nm, together confirming their anisotropic nature. Further, the MTT assay demonstrated promising anticancer effects of ANI Ag NPs with an IC50 value of ∼7 μg/mL against HuT-78 cells. These sustainable anisotropic silver nanoparticles exhibited approximately four times better cytotoxic ability (at and above 10 μg/mL concentrations) than L-asparaginase against HuT-78 cells (a human T lymphoma cell line). Apoptosis analysis by Wright-Geimsa, Annexin-V, and DAPI staining indicated the role of apoptosis in ANI Ag NPs-mediated cell death. The measurement of NO, and Bcl2 and cleaved caspase-3 levels by colorimetric method and immunoblotting, respectively suggested their involvement in ANI Ag NPs-elicited apoptosis. The findings indicate that the biogenic approach proposed herein holds tremendous promise for the rapid and straightforward design of novel multifunctional nanoparticles for the treatment of T cell malignancies.

Impact of Surface Charge-Tailored Gold Nanorods for Selective Targeting of Mitochondria in Breast Cancer Cells Using Photodynamic Therapy

Herein, the impact of surface charge tailored of gold nanorods (GNRs) on breast cancer cells (MCF-7 and MDA-MB-231) upon conjugation with triphenylphosphonium (TPP) for improved photodynamic therapy (PDT) targeting mitochondria was studied. The salient features of the study are as follows: (i) positive (CTAB@GNRs) and negative (PSS-CTAB@GNRs) surface-charged gold nanorods were developed and characterized; (ii) the mitochondrial targeting efficiency of gold nanorods was improved by conjugating TPP molecules; (iii) the conjugated nanoprobes (TPP-CTAB@GNRs and TPP-PSS-CTAB@GNRs) were evaluated for PDT in the presence of photosensitizer (PS), 5-aminolevulinic acid (5-ALA) in breast cancer cells; (iv) both nanoprobes (TPP-CTAB@GNRs and TPP-PSS-CTAB@GNRs) induce apoptosis, damage DNA, generate reactive oxygen species, and decrease mitochondrial membrane potential upon 5-ALA-based PDT; and (v) 5-ALA-PDT of two nanoprobes (TPP-CTAB@GNRs and TPP-PSS-CTAB@GNRs) impact cell signaling (PI3K/AKT) pathway by upregulating proapoptotic genes and proteins. Based on the results, we confirm that the positively charged (rapid) nanoprobes are more advantageous than their negatively (slow) charged nanoprobes. However, depending on the kind and degree of cancer, both nanoprobes can serve as efficient agents for delivering anticancer therapy.

Multimodal In Vivo Imaging of Retinal and Choroidal Vascular Occlusion

Photoacoustic microscopy (PAM) is an emerging retinal imaging technique that can provide high spatial resolution and high contrast of chorioretinal vessels. PAM is compatible with optical coherence tomography (OCT) and fluorescence imaging, allowing for development of a multimodal imaging system that combines these imaging modalities into one. This study presents a non-invasive, label-free in vivo imaging of retinal and choroidal vascular occlusion using multimodal imaging system, including PAM and OCT. Both retinal vein occlusion (RVO) and choroidal vascular occlusion (CVO) were clearly identified selectively using a spectroscopic PAM imaging. RVO and CVO were created in six rabbits using laser photocoagulation. The dynamic changes of retinal vasculature were observed and evaluated using color fundus photography, fluorescein angiography, OCT, and PAM. The position of RVO and CVO were imaged with different wavelengths ranging from 532 to 600 nm. The data shows that occluded vessels were clearly distinguished from the surrounding retinal vessels on the PAM images. This advanced imaging system is a promising technique for imaging retinal ischemia in preclinical disease models.

Gold Nanorod-Decorated Metallic MoS2 Nanosheets for Synergistic Photothermal and Photodynamic Antibacterial Therapy

Light-responsive nanocomposites have become increasingly attractive in the biomedical field for antibacterial applications. Visible-light-activated metallic molybdenum disulfide nanosheets (1T-MoS2 NSs) and plasmonic gold nanorods (AuNRs) with absorption at a wavelength of 808 nm were synthesized. AuNR nanocomposites decorated onto 1T-MoS2 NSs (MoS2@AuNRs) were successfully prepared by electrostatic adsorption for phototherapy applications. Based on the photothermal effect, the solution temperature of the MoS2@AuNR nanocomposites increased from 25 to 66.7 °C after 808 nm near-infrared (NIR) laser irradiation for 10 min. For the photodynamic effect, the MoS2@AuNR nanocomposites generated reactive oxygen species (ROS) under visible light irradiation. Photothermal therapy and photodynamic therapy of MoS2@AuNRs were confirmed against E. coli by agar plate counts. Most importantly, the combination of photothermal therapy and photodynamic therapy from the MoS2@AuNR nanocomposites revealed higher antibacterial activity than photothermal or photodynamic therapy alone. The light-activated MoS2@AuNR nanocomposites exhibited a remarkable synergistic effect of photothermal therapy and photodynamic therapy, which provides an alternative approach to fight bacterial infections.

Long-Term, Noninvasive In Vivo Tracking of Progenitor Cells Using Multimodality Photoacoustic, Optical Coherence Tomography, and Fluorescence Imaging

Stem cell regenerative medicine therapies have emerged as promising treatments for currently incurable diseases. A remaining challenge for cell therapies is the ability to track the migration and distribution of the transplanted cells in a long-term, noninvasive manner in vivo to assess their efficacy. This study develops a noninvasive, and high spatial resolution photoacoustic microscopy (PAM) and optical coherence tomography (OCT) imaging system for in vivo tracking of subretinally injected progenitor human retinal pigment epithelium cells (ARPE-19) labeled with chainlike gold nanoparticle (CGNP) clusters in RPE damage. CGNP provided significant PAM, OCT, and fluorescence signals to selectively track the migration of ARPE-19 cells in living rabbit eyes for 3 months. PAM and OCT imaging allow accurate anatomical information to determine the exact retinal layer in which the transplanted ARPE-19 cells are located which was confirmed by histology. This presents an efficient and advanced technology to visualize fundamental biological processes of cell therapies in complex in vivo environments in real time.

In Vivo Subretinal ARPE-19 Cell Tracking Using Indocyanine Green Contrast-Enhanced Multimodality Photoacoustic Microscopy, Optical Coherence Tomography, and Fluorescence Imaging for Regenerative Medicine

Purpose

Cell-based regenerative therapies are being investigated as a novel treatment method to treat currently incurable eye diseases, such as geographic atrophy in macular degeneration. Photoacoustic imaging is a promising technology which can visualize transplanted stem cells in vivo longitudinally over time in the retina. In this study, a US Food and Drug Administration (FDA)-approved indocyanine green (ICG) contrast agent is used for labeling and tracking cell distribution and viability using multimodal photoacoustic microscopy (PAM), optical coherence tomography (OCT), and fluorescence imaging.

Methods

Twelve rabbits (2.4–3.4 kg weight, 2–4 months old) were used in the study. Human retinal pigment epithelial cells (ARPE-19) were labeled with ICG dye and transplanted in the subretinal space in the rabbits. Longitudinal PAM, OCT, and fluorescence imaging was performed for up to 28 days following subretinal administration of ARPE-19 cells.

Results

Cell migration location, viability, and cell layer thickness were clearly recognized and determined from the fluorescence, OCT, and PAM signal. The in vivo results demonstrated that fluorescence signal increased 37-fold and PAM signal enhanced 20-fold post transplantation.

Conclusions

This study demonstrates that ICG-assisted PAM, OCT, and fluorescence imaging can provide a unique platform for tracking ARPE-19 cells longitudinally with high resolution and high image contrast.

Translational Relevance

Multimodal PAM, OCT, and fluorescence in vivo imaging with ICG can improve our understanding of the fate, distribution, and function of regenerative cell therapies over time nondestructively.

Functionalized contrast agents for multimodality photoacoustic microscopy, optical coherence tomography, and fluorescence microscopy molecular retinal imaging

Near-infrared (NIR) targeting contrast agents have been investigated as great photoabsorbers to improve photoacoustic microscopy (PAM), OCT, and fluorescence imaging contrast for visualization of various diseases. In ophthalmology, a limited number of NIR contrast agents have been approved for clinical use. Recently, gold nanoparticles with different size and shapes have been developed for molecular imaging. This chapter provides the principles of multimodality PAM, OCT, and fluorescence imaging as well as a brief overview of contrast agents for optical imaging. A detailed protocol for the fabrication of discrete colloidal gold nanoparticles (GNPs), synthesis of functionalized RGD-conjugated chain-like GNP (CGNP) clusters labeled with indocyanine green (ICG) fluorescence dye (ICG@CGNP clusters-RGD), and validation of the synthesized nanoparticles to evaluate newly developed blood vessels in the retina, named choroidal neovascularization (CNV), is described. Using RGD peptide, ICG@CGNPs clusters-RGD can bind integrin which is expressed on activated endothelial cells and newly developed CNV. The targeting efficiency of nanoparticles is monitored by multimodality PAM, OCT, and fluorescence imaging longitudinally.

Indocyanine green-enhanced multimodal photoacoustic microscopy and optical coherence tomography molecular imaging of choroidal neovascularization

Photoacoustic microscopy (PAM) has great potential for visualization of the microvasculature with high spatial resolution and contrast. Early detection and differentiation of newly developed blood vessels named choroidal neovascularization (CNV) from normal vasculature remains a challenge in ophthalmology. Exogenous contrast agents can assist with improving PAM sensitivity, leading to differentiation of CNV. Here, an FDA-approved indocyanine green (ICG) was utilized as a PAM contrast agent. ICG was conjugated with RGD peptides, allowing the ICG to bind to the integrin expressed in CNV. Molecular PAM imaging showed that ICG-RGD can target CNV for up to 5 days post intravenous administration in living rabbits with a model of CNV. The PAM image sensitivity and image contrast were significantly enhanced by 15-fold at 24 h post-injection. Overall, the presented approach demonstrates the possibility of targeted ICG to be employed in PAM molecular imaging, allowing more precise evaluation of neovascularization.

Facet-dependent gold nanocrystals for effective photothermal killing of bacteria

Gold-based plasmonic nanocrystals have been extensively developed for noninvasive photothermal therapy. In this study, gold nanorods (AuNRs) with (200) plane and gold nanobipyramids (AuNBPs) with (111) plane were utilized as photothermal agents for noninvasive photothermal therapy. With longitudinal surface plasma bands at ~808 nm, both of AuNRs and AuNBPs revealed photothermal capability and reversibility of laser response under 808-nm near-infrared (NIR) laser irradiation. Moreover, AuNBPs with (111) plane exhibited higher photothermal performance than that of AuNRs with (200) plane under NIR laser irradiation. Density function theory (DFT) simulations revealed that water adsorption energy followed the order Au(111) < Au(100), indicating that the water was easily desorbed on the Au(111) surface for photothermal heating. For the photothermal therapy against Escherichia coli (E. coli), AuNBPs also exhibited higher efficiency compared to that of AuNRs under NIR laser irradiation. Combination of experimental photothermal therapy and DFT simulations demonstrated that AuNBPs with (111) plane were better photothermal agents than that of AuNRs with (100) plane.

Controllable Self-Assembly of SERS Hotspots in Liquid Environment

Controllable synthesis of novel metal nanoparticles and effective capture of hotspots are of great significance for SERS (surface-enhanced Raman spectroscopy) detection. Therefore, in this paper, a green controllable synthesis method of gold nanoparticle was achieved via epigallocatechin gallate reduction. Different morphologies of gold nanoparticles were synthesized just by changing the solution pH values, and the growth kinetics of AuNPs (gold nanoparticles) were systematically studied. The synthetic AuNPs were put in a droplet to study dynamic variations of self-assembly SERS hotspots from the liquid sol state to the solid dry state. The addition of halogen ions in the droplet can controllably regulate the self-assembly three-dimensional hotspot model of gold nanoparticles in the evaporation process of a droplet, during which the most enhancement effect can be easily captured. The dynamically changing images of nanoparticles in the process were graphically described based on the internal interaction forces of a droplet. Two stronger areas in the changes of SERS intensity were achieved with a high concentration of halogen ions, while only one maximum intensity area was obtained with a low concentration of halogen ions added. This method can effectively avoid complex and unpredictable microenvironments of SERS substrates in the liquid drop, further improving the reproducibility of SERS detection as well as broadening it to biological applications.

Chain-like gold nanoparticle clusters for multimodal photoacoustic microscopy and optical coherence tomography enhanced molecular imaging

Colloidal gold nanoparticles (GNPs) serve as promising contrast agents in photoacoustic (PA) imaging, yet their utility is limited due to their absorption peak in the visible window overlapping with that of hemoglobin. To overcome such limitation, this report describes an ultrapure chain-like gold nanoparticle (CGNP) clusters with a redshift peak wavelength at 650 nm. The synthesized CGNP show an excellent biocompatibility and photostability. These nanoparticles are conjugated with arginine-glycine-aspartic acid (RGD) peptides (CGNP clusters-RGD) and validated in 12 living rabbits to perform multimodal photoacoustic microscopy (PAM) and optical coherence tomography (OCT) for visualization of newly developed blood vessels in the sub-retinal pigment epithelium (RPE) space of the retina, named choroidal neovascularization (CNV). The PAM system can achieve a 3D PAM image via a raster scan of 256 × 256 pixels within a time duration of 65 s. Intravenous injection of CGNP clusters-RGD bound to CNV and resulted in up to a 17-fold increase in PAM signal and 176% increase in OCT signal. Histology indicates that CGNP clusters could disassemble, which may facilitate its clearance from the body.

This manuscript presents ultrapure chain-like gold nanoparticle clusters with red shifted absorption and shows their potential for in vivo imaging in living rabbits. The nanoparticles demonstrate a 17-fold increase in photoacoustic microscopy signal and 176% increase in optical coherence tomography signal.

Single source precursor synthesized CuS nanoparticles for NIR phototherapy of cancer and photodegradation of organic carcinogen

Herein, we report cost effective and body compatible CuS nanoparticles (NPs) derived from a single source precursor as photothermal agent for healing deep cancer and photocatalytic remediation of organic carcinogens. These NPs efficiently kill MCF7 cells (both in vivo and in vitro) under NIR irradiation by raising the temperature of tumor cells. Such materials can be used for the treatment of deep cancer as they can produce a heating effect using high wavelength and deeply penetrating NIR radiation. Furthermore, CuS NPs under solar light irradiation efficiently convert p-nitrophenol (PNP), an environmental carcinogen, to p-aminophenol (PAP) of pharmaceutical implication. In a nutshell, CuS can be used for the treatment of deep cancer and for the remediation of carcinogenic pollutants. There seems an intrinsic connection between the two functions of CuS NPs that need to be explored in length.

Supramolecular Vesicles Based on Amphiphilic Pillar[n]arenes for Smart Nano-Drug Delivery

Supramolecular vesicles are the most popular smart nano-drug delivery systems (SDDs) because of their unique cavities, which have high loading carrying capacity and controlled-release action in response to specific stimuli. These vesicles are constructed from amphiphilic molecules via host-guest complexation, typically with targeted stimuli-responsive units, which are particularly important in biotechnology and biomedicine applications. Amphiphilic pillar[n]arenes, which are novel and functional macrocyclic host molecules, have been widely used to construct supramolecular vesicles because of their intrinsic rigid and symmetrical structure, electron-rich cavities and excellent properties. In this review, we first explain the synthesis of three types of amphiphilic pillar[n]arenes: neutral, anionic and cationic pillar[n]arenes. Second, we examine supramolecular vesicles composed of amphiphilic pillar[n]arenes recently used for the construction of SDDs. In addition, we describe the prospects for multifunctional amphiphilic pillar[n]arenes, particularly their potential in novel applications.

Gold nanospheres and nanorods for anti-cancer therapy: comparative studies of fabrication, surface-decoration, and anti-cancer treatments

Various gold nanoparticles have been explored as cancer therapeutics because they can be widely engineered for use as efficient drug carriers and diagnostic agents, and in photo-irradiation therapy. In the current review, we focused on shape-dependent biomedical applications of gold nanoparticles including gold nanospheres and nanorods. Fabrication and functionalization strategies of two different gold nanoparticles for anti-cancer therapy are introduced and the distinguishing performance depending on the shape is discussed to suggest the best carrier shape for specific applications. Moreover, recent advances in anti-cancer immunotherapy using gold nano-carriers are discussed. Thus, this comparative review can be helpful in deciding on suitable shapes and surface-modification strategies for preparing various gold nanoparticle-based therapeutics in anti-cancer therapy.

Mannoside-Modified Branched Gold Nanoparticles for Photothermal Therapy to MDA-MB-231 Cells

Recently, gold nanoparticles (Au NPs) have been used to study the treatment of malignant tumors due to their higher biocompatibility and lesser toxicity. In addition, they can be excited through a specific wavelength to produce oscillating plasmonic photothermal therapy (PPTT) on the basis of the localized surface plasma resonance (LSPR) effect. Au NPs can be heated to kill cancer cells in specific parts of the body in a noninvasive manner. In this study, branched gold nanoparticles (BAu NPs) were prepared by mixing HAuCl₄ in a 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution in a molar ratio of 1:2000. The UV–vis absorption peak was detected in the range of 700–1000 nm. Subsequently, BAu NPs were chemically linked to a thiol-modified mannoside molecule via a stable sulfur–Au covalent bond (Man@BAu NPs). Due to the presence of abundant mannose receptors on human-breast-cancer cells, MDA-MB-231, Man@BAu NPs were found to be abundant inside cancer cells. After irradiating the Man@BAu NP-laden MDA-MB231 switch with a near-infrared (NIR) laser at 808 nm wavelength, the photothermal-conversion effect raised the surface temperature of Man@BAu NPs, thus inducing cell death. Our experiment results demonstrated the advantages of applying Man@BAu NPs in inducing cell death in MDA-MB-231.

A novel, rapid, seedless, in situ synthesis method of shape and size controllable gold nanoparticles using phosphates

We hereby report a novel synthesis method of size and shape controllable gold nanoparticles that is rapid, in situ and seedless. Unlike most currently employed size and shape controllable synthesis methods, it takes place in a single step under room temperature within ~15 minutes. While mixtures of gold nanospheres around 70 nm and gold nanoplates with width ranging from 100 nm to 1000 nm can be synthesized in about 15 minutes by standard synthesis method using N-2-hydroxyethylpiperazine-N-2-ethanesulphonic acid (HEPES) to reduce Au(III), gold nanoflowers or mixtures of smaller gold nanospheres and nanoplates can be synthesized with the addition of disodium phosphate (Na2HPO4) or monosodium phosphate (NaH2PO4), respectively. Increasing the concentration of phosphate added significantly reduces the formation time of gold nanoparticles to seconds. By increasing the molar ratio of Na2HPO4: HEPES and NaH2PO4: HEPES, the size of gold nanoflowers and gold nanoparticle mixtures can be tuned from ~60 nm down to 1 nm and from ~70 nm to ~2.5 nm, respectively. The systematic structural changes are accompanied by similarly systematic colour changes associated with shifting of the surface plasmon resonance. The proposed mechanism of the synthesis process is also presented.

Contrast Agent Enhanced Multimodal Photoacoustic Microscopy and Optical Coherence Tomography for Imaging of Rabbit Choroidal and Retinal Vessels in vivo

Multimodal imaging with photoacoustic microscopy (PAM) and optical coherence tomography (OCT) can be an effective method to evaluate the choroidal and retinal microvasculature. To improve the efficiency for visualizing capillaries, colloidal gold nanoparticles (AuNPs) have been applied as a multimodal contrast agent for both OCT and PAM imaging by taking advantage of the strong optical scattering and the strong optical absorption of AuNPs due to their surface plasmon resonance. Ultra-pure AuNPs were fabricated by femtosecond laser ablation, capped with polyethylene glycol (PEG), and administered to 13 New Zealand white rabbits and 3 Dutch Belted pigmented rabbits. The synthesized PEG-AuNPs (20.0 ± 1.5 nm) were demonstrated to be excellent contrast agents for PAM and OCT, and do not demonstrate cytotoxicity to bovine retinal endothelial cells in cell studies. The image signal from the retinal and choroidal vessels in living rabbits was enhanced by up to 82% for PAM and up to 45% for OCT, respectively, by the administered PEG-AuNPs, which enables detection of individual blood vessels by both imaging modalities. The biodistribution study demonstrated the AuNP accumulated primarily in the liver and spleen. Histology and TUNEL staining did not indicate cell injury or death in the lung, liver, kidney, spleen, heart, or eyes up to seven days after AuNP administration. PEG-AuNPs offer an efficient and safe contrast agent for multimodal ocular imaging to achieve improved characterization of microvasculature.

Development of anisamide-targeted PEGylated gold nanorods to deliver epirubicin for chemo-photothermal therapy in tumor-bearing mice

BACKGROUND

Gold nanorods (AuNRs), due to the optical and electronic properties namely the surface plasma resonance, have been developed to achieve the light-mediated photothermal therapy (PTT) for cancer. However, PTT alone may suffer from inefficient tumor killing. Recently, the combination of PTT and chemotherapy has been utilized to achieve synergistic anticancer effects.

METHODS

In this study, AuNRs capped with hexadecyltrimethylammonium bromide (CTAB), poly(acrylic acid) (PAA), and PEGylated anisamide (a ligand known to target the sigma receptor) have been developed to produce a range of negatively charged anisamide-targeted PEGylated AuNRs (namely Au-CTAB-PAA-PEG-AA) for the combination of PTT and chemotherapy (termed as chemo-photothermal therapy [CPTT]). Epirubicin (EPI, an anthracycline drug) was efficiently loaded onto the surface of Au800-CTAB-PAA-PEG-AA via the electrostatic interaction forming Au800-CTAB-PAA-PEG-AA.EPI complex.

RESULTS

The resultant complex demonstrated pH-dependent drug release, facilitated nucleus trafficking of EPI, and induced antiproliferative effects in human prostate cancer PC-3 cells. When Au800-CTAB-PAA-PEG-AA.EPI complex was further stimulated with desired laser irradiation, the synergistic outcome was evident in PC-3 xenograft mice.

CONCLUSION

These results demonstrate a promising strategy for clinical application of CPTT in cancer.

In Vivo 3D Imaging of Retinal Neovascularization Using Multimodal Photoacoustic Microscopy and Optical Coherence Tomography Imaging

The pathological process of neovascularization of the retina plays a critical role in causing vision loss in several diseases, including diabetes, retinal vein occlusion, and sickle cell disease. Retinal neovascularization can lead to vitreous hemorrhage and retinal detachment, yet the pathological process of neovascularization is a complex phenomenon under active investigation. Understanding and monitoring retinal neovascularization is critically important in clinical ophthalmology. This study describes a novel multimodal ocular imaging system which combines photoacoustic microscopy (PAM) and a spectral domain optical coherence tomography (SD-OCT) to improve the visualization of retinal neovascularization (RNV), their depth, and the surrounding anatomy in living rabbits. RNV was induced in New Zealand rabbits by intravitreal injection of vascular endothelial growth factor (VEGF). The retinal vasculature before and after injection at various times was monitored and evaluated using multimodal imaging including color fundus photography, fluorescein angiography (FA), OCT, and PAM. In vivo experiments demonstrate that PAM imaging distinctly characterized the location as well as the morphology of individual RNV with high contrast at a safe laser energy of 80 nJ. SD-OCT was used to identify a cross-sectional structure of RNV. In addition, dynamic changes in the retinal morphology and retinal neovascularization were observed at day 4, 5, 6, 7, 9, 11, 14, 28, and day 35 after VEGF injection. PAM demonstrated high-resolution optical absorption of hemoglobin and vascular imaging of the retina and choroid with increased depth of penetration. With the current multimodal imaging system, RNV can be easily visualized in both 2D and 3D angiography. This multimodal ocular imaging system provides improved characterization of the microvasculature in a safe manner in larger rabbit eyes.

Multi-wavelength, en-face photoacoustic microscopy and optical coherence tomography imaging for early and selective detection of laser induced retinal vein occlusion

Multi-wavelength en face photoacoustic microscopy (PAM) was integrated with a spectral domain optical coherence tomography (SD-OCT) to evaluate optical properties of retinal vein occlusion (RVO) and retinal neovascularization (RNV) in living rabbits. The multi-wavelength PAM of the RVO and RNV were performed at several wavelengths ranging from 510 to 600 nm. Rose Bengal-induced RVO and RNV were performed and evaluated on eight rabbits using color fundus photography, fluorescein angiography, OCT, and spectroscopic en face PAM. In vivo experiment demonstrates that the spectral variation of photoacoustic response was achieved. The location and the treatment margins of the occluded vasculature as well as the morphology of individual RNV were obtained with high contrast at a laser energy of 80 nJ, which was only half of the American National Standards Institute safety limit. In addition, dynamic changes in the retinal morphology and retinal neovascularization were administered using PA spectroscopy at numerous time points: 0, 3, 7, 14, 21, 28, and 35 days after photocoagulation. The proposed multi-wavelength spectroscopic PAM imaging may provide a potential imaging platform to differentiate occluded retinal vasculature and to improve characterization of microvasculature in a safe and efficient manner.

Photoacoustic Ophthalmoscopy: Principle, Application, and Future Directions

Photoacoustic ophthalmoscopy (PAOM) is a novel, hybrid, non-ionizing, and non-invasive imaging technology that has been used to assess the retina. PAOM can provide both anatomic and functional retinal characterizations with high resolution, high sensitivity, high contrast, and a high depth of penetration. Thus, ocular diseases can be precisely detected and visualized at earlier stages, resulting in an improved understanding of pathophysiology, improved management, and the improved monitoring of retinal treatment to prevent vision loss. To better visualize ocular components such as retinal vessels, choroidal vessels, choroidal neovascularization, retinal neovascularization, and the retinal pigment epithelium, an advanced multimodal ocular imaging platform has been developed by a combination of PAOM with other optical imaging techniques such as optical coherence tomography (OCT), scanning laser ophthalmoscopy (SLO), and fluorescence microscopy. The multimodal images can be acquired from a single imaging system and co-registered on the same image plane, enabling an improved evaluation of disease. In this review, the potential application of photoacoustic ophthalmoscopy in both research and clinical diagnosis are discussed as a medical screening technique for the visualization of various ocular diseases. The basic principle and requirements of photoacoustic ocular imaging are introduced. Then, various photoacoustic microscopy imaging systems of the retina in animals are presented. Finally, the future development of PAOM and multimodal imaging is discussed.

Developing Hollow-Channel Gold Nanoflowers as Trimodal Intracellular Nanoprobes

Gold nanoparticles-enabled intracellular surface-enhanced Raman spectroscopy (SERS) provides a sensitive and promising technique for single cell analysis. Compared with spherical gold nanoparticles, gold nanoflowers, i.e., flower-shaped gold nanostructures, can produce a stronger SERS signal. Current exploration of gold nanoflowers for intracellular SERS has been considerably limited by the difficulties in preparation, as well as background signal and cytotoxicity arising from the surfactant capping layer. Recently, we have developed a facile and surfactant-free method for fabricating hollow-channel gold nanoflowers (HAuNFs) with great single-particle SERS activity. In this paper, we investigate the cellular uptake and cytotoxicity of our HAuNFs using a RAW 264.7 macrophage cell line, and have observed effective cellular internalization and low cytotoxicity. We have further engineered our HAuNFs into SERS-active tags, and demonstrated the functionality of the obtained tags as trimodal nanoprobes for dark-field and fluorescence microscopy imaging, together with intracellular SERS.

Nanomaterials as nanocarriers: a critical assessment why these are multi-chore vanquisher in breast cancer treatment

Breast cancer is a group of diseases with various subtypes and leads to high mortality throughout the globe. Various conventional techniques are in practice to cure breast cancer but these techniques are linked with various shortcomings. Mostly these treatments are not site directed and cause toxicity towards normal cells. In order to overcome these issues, we need smart system that can deliver anticancer drugs to specific sites. Targeted drug delivery can be achieved via passive or active drug delivery using nanocarriers. This mode of drug delivery is more effective against breast cancer and may help in the reduction of mortality rate. Potentially used nanocarriers for targeted drug delivery belong to organic and inorganic molecules. Various FDA approved nano products are in use to cure breast cancer. However, body's defense system is main limitation for potential use of nano systems. However, this can be overcome by surface modification of nanocarriers. In this review, breast cancer and its types, targeted drug delivery and nanocarriers used to cure breast cancer are discussed. By progressing nanotechnology, we will be able to fight against this life threatening issue and serve the humanity, which is the basic aim of scientific knowledge.

Using Multifunctional Peptide Conjugated Au Nanorods for Monitoring β-amyloid Aggregation and Chemo-Photothermal Treatment of Alzheimer's Disease

Development of sensitive detectors of Aβ aggregates and effective inhibitors of Aβ aggregation are of diagnostic importance and therapeutic implications for Alzheimer's disease (AD) treatment. Herein, a novel strategy has been presented by self-assembly of peptide conjugated Au nanorods (AuP) as multifunctional Aβ fibrillization detectors and inhibitors. Our design combines the unique high NIR absorption property of AuNRs with two known Aβ inhibitors, Aβ15-20 and polyoxometalates (POMs). The synthesized AuP can effectively inhibit Aβ aggregation and dissociate amyloid deposits with NIR irradiation both in buffer and in mice cerebrospinal fluid (CSF), and protect cells from Aβ-related toxicity upon NIR irradiation. In addition, with the shape and size-dependent optical properties, the nanorods can also act as effective diagnostic probes to sensitively detect the Aβ aggregates. This is the first report to integrate 3 segments, an Aβ-targeting element, a reporter and inhibitors, in one drug delivery system for AD treatment.

Seedless synthesis and SERS characterization of multi-branched gold nanoflowers using water soluble polymers

We report for the first time, the aqueous-based synthesis of multibranched, monodispersed gold nanoflowers (AuNFs) using pyromellitic dianhydride-p-phenylene diamine - PPDDs at room temperature. AuNF synthesis was achieved using PPDDs that converts Au precursor (Au³⁺) into AuNFs while serving as both the reducing and directional agent. The resulting branched AuNFs exhibited different degrees of anisotropy and protuberance lengths obtained by modulating the ratio of PPDDs and HAuCl₄·3H₂O. The surface roughness obtained ranged from small bud-like protuberances to elongated spikes, which enabled the tuning of the optical properties of the nanoparticles from ∼450 to 1100 nm. Systematic analysis revealed that the generation of urchin-like particles as well as their size depended on the PPDDs/HAuCl₄·3H₂O ratio. At a medium concentration of the precursor, spherical nanoparticles were formed. Whereas at lower precursor concentrations, urchin-like nanoparticles were obtained with their size and protuberances length increasing at even lower HAuCl₄·3H₂O concentration. Increasing the temperature to 100 °C resulted in the enhancement of the anisotropy of the AuNFs. The resulting gold nanoflowers exhibited an enhanced performance in surface-enhanced Raman scattering (SERS). This work provides a unique approach for anisotropic particle synthesis using water soluble polymer and greener approaches. The fabricated AuNFs exhibited variable UV-vis absorption and SERS enhancement as a function of branch morphology, indicating their potential application in biolabeling, biosensing, imaging, and therapeutic applications.

Biocompatible astaxanthin as a novel marine-oriented agent for dual chemo-photothermal therapy

The photothermal effect of a marine-oriented xanthophyll carotenoid, astaxanthin (AXT), was characterized based on its potential absorption of visible laser light and conversion of optical light energy into heat for thermal treatment. As an antioxidant and anticancer agent, AXT extracted from marine material can be utilized for photothermal therapy due to its strong light absorption. The current study investigated the feasibility of the marine-based material AXT to increase the therapeutic efficacy of chemo-photothermal therapy (PTT) by assessing photothermal sessions in both cells and tumor tissues. A quasi-cw Q-switched 80 W 532 nm laser system was utilized to induce thermal necrosis in in vitro and in vivo models. An in vitro cytotoxicity study of AXT was implemented using squamous cell carcinoma (VX2) and macrophage (246.7) cell lines. In vivo PTT experiments were performed on 17 rabbits bearing VX2 tumors on their eyes that were treated with or without intratumoral injection of AXT at a dose of 100 μl (300 μg/ml) followed by laser irradiation at a low irradiance of 0.11 W/cm². Fluorescence microscopy images revealed cellular death via apoptosis and necrosis owing to the dual chemo-photothermal effects induced by AXT. In vivo experimental results demonstrated that the AXT-assisted irradiation entailed a temperature increase by 30.4°C after tumor treatment for 4 min. The relative variations in tumor volume confirmed that the tumors treated with both AXT and laser irradiation completely disappeared 14 days after treatment, but the tumors treated under other conditions gradually grew. Due to selective light absorption, AXT-assisted laser treatment could be an effective thermal therapy for various drug-resistant cancers.

Gold nanoparticles as potent anticancer agent: green synthesis, characterization, and in vitro study

High quality colloidal gold nanoparticles with promising anticancer activity were synthesized using Taxus baccata extracts.

Highly stable and biocompatible gold nanorod–DNA conjugates as NIR probes for ultrafast sequence-selective DNA melting

Colloidally stable and biocompatible DNA-functionalized Au nanorods are proved as NIR-addressable probes and mediators for ultrafast and sequence-selective DNA melting.

A near-infrared light-controlled system for reversible presentation of bioactive ligands using polypeptide-engineered functionalized gold nanorods

A near-infrared light-controlled hybrid platform with polypeptide-engineered functionalized gold nanorods has been designed for reversible presentation of the immobilized ligands to cell surface receptors on the engineered materials.

One-Step Generation of Multifunctional Polyelectrolyte Microcapsules via Nanoscale Interfacial Complexation in Emulsion (NICE)

Polyelectrolyte microcapsules represent versatile stimuli-responsive structures that enable the encapsulation, protection, and release of active agents. Their conventional preparation methods, however, tend to be time-consuming, yield low encapsulation efficiency, and seldom allow for the dual incorporation of hydrophilic and hydrophobic materials, limiting their widespread utilization. In this work, we present a method to fabricate stimuli-responsive polyelectrolyte microcapsules in one step based on nanoscale interfacial complexation in emulsions (NICE) followed by spontaneous droplet hatching. NICE microcapsules can incorporate both hydrophilic and hydrophobic materials and also can be induced to trigger the release of encapsulated materials by changes in the solution pH or ionic strength. We also show that NICE microcapsules can be functionalized with nanomaterials to exhibit useful functionality, such as response to a magnetic field and disassembly in response to light. NICE represents a potentially transformative method to prepare multifunctional nanoengineered polyelectrolyte microcapsules for various applications such as drug delivery and cell mimicry.

Photosensitizer-Loaded pH-Responsive Hollow Gold Nanospheres for Single Light-Induced Photothermal/Photodynamic Therapy

Novel photoinduced triple-response antitumor therapeutic system based on hollow gold nanospheres (HAuNS), pH (low) insertion peptide (pHLIP), and Chlorin e6 (Ce6), was reported for the first time. The system was able to intracellularly deliver the nanocarriers by the transmembrane ability of pHLIP at the condition of pH 6.2. Ce6 and pHLIP were then released from the surface of the carriers due to the weakening electrostatic interaction with HAuNS under the photoirradiation. Herein, HAuNS performed two different functions: (1) as a nanocarrier because of the excellent loading capability; (2) experienced the photothermal therapy (PTT) effect as a photothermal coupling agent (PTCA), thus enhancing the photodynamic therapy (PDT) effect of Ce6.

Synthesis of Absorption-Dominant Small Gold Nanorods and Their Plasmonic Properties

Absorption-dominant small Au nanorods with diameters of less than 10 nm are prepared using a facile seed-mediated growth method. The diameters of the small gold nanorods range from 6 to 9 nm, and their lengths vary from 16 to 45 nm. Their aspect ratios can be tailored from 2.7 to 4.7. As a result, the longitudinal plasmon resonance wavelengths are readily tunable from ∼720 nm to ∼830 nm by changing the seed-to-Au(III) molar ratio in the growth solution. The fractions of the scattering in the total extinction of the small Au nanorods are found to be in the range of 0.005 to 0.025 with finite-difference time-domain simulations, confirming that the extinction values of these small Au nanorods are dominantly contributed to by the light absorption. Moreover, the small Au nanorod sample is coated with a dense silica layer for photothermal therapy with three cell lines. It shows improved photothermal therapy performance compared to a large Au nanorod sample for the same cellular Au contents. Our study suggests that small Au nanorods are promising light absorbers and photothermal therapy agents.

Breast cancer photothermal therapy based on gold nanorods targeted by covalently-coupled bombesin peptide

Photothermal therapy, a minimally invasive treatment method for killing cancers cells, has generated a great deal of interest. In an effort to improve treatment efficacy and reduce side effects, better targeting of photoabsorbers to tumors has become a new concept in the battle against cancer. In this study, a bombesin (BBN) analog that can bind to all gastrin-releasing peptide (GRP) receptor subtypes was bound covalently with gold nanorods (GNRs) using Nanothinks acid as a link. The BBN analog was also coated with poly(ethylene glycol) to increase its stability and biocompatibility. The interactions were confirmed by ultraviolet-visible and Fourier transform infrared spectroscopy. A methylthiazol tetrazolium assay showed no cytotoxicity of the PEGylated GNR-BBN conjugate. The cell binding and internalization studies showed high specificity and uptake of the GNR-BBN-PEG conjugate toward breast cancer cells of the T47D cell line. The in vitro study revealed destruction of the T47D cells exposed to the new photothermal agent combined with continuous-wave near-infrared laser irradiation. The biodistribution study showed significant accumulation of the conjugate in the tumor tissue of mice with breast cancer. The in vivo photothermal therapy showed the complete disappearance of xenographted breast tumors in the mouse model.

In situ amplification of intracellular microRNA with MNAzyme nanodevices for multiplexed imaging, logic operation, and controlled drug release

MicroRNAs (miRNAs), as key regulators in gene expression networks, have participated in many biological processes, including cancer initiation, progression, and metastasis, indicative of potential diagnostic biomarkers and therapeutic targets. To tackle the low abundance of miRNAs in a single cell, we have developed programmable nanodevices with MNAzymes to realize stringent recognition and in situ amplification of intracellular miRNAs for multiplexed detection and controlled drug release. As a proof of concept, miR-21 and miR-145, respectively up- and down-expressed in most tumor tissues, were selected as endogenous cancer indicators and therapy triggers to test the efficacy of the photothermal nanodevices. The sequence programmability and specificity of MNAzyme motifs enabled the fluorescent turn-on probes not only to sensitively profile the distributions of miR-21/miR-145 in cell lysates of HeLa, HL-60, and NIH 3T3 (9632/0, 14147/0, 2047/421 copies per cell, respectively) but also to visualize trace amounts of miRNAs in a single cell, allowing logic operation for graded cancer risk assessment and dynamic monitoring of therapy response by confocal microscopy and flow cytometry. Furthermore, through general molecular design, the MNAzyme motifs could serve as three-dimensional gatekeepers to lock the doxorubicin inside the nanocarriers. The drug nanocarriers were exclusively internalized into the target tumor cells via aptamer-guided recognition and reopened by the endogenous miRNAs, where the drug release rates could be spatial-temporally controlled by the modulation of miRNA expression. Integrated with miRNA profiling techniques, the designed nanodevices can provide general strategy for disease diagnosis, prognosis, and combination treatment with chemotherapy and gene therapy.

Polyelectrolyte-coated gold nanorods and their biomedical applications

Gold nanorods (GNRs) have been extensively used in biomedical applications, because of their favourable optical properties. Their longitudinal surface plasmon resonance can be tuned, providing a strong near-infrared (NIR) extinction coefficient peak within the tissue transparency window. However, the modification of the surface of GNRs is essential before they can be used for biomedical applications. The number of GNRs taken up by cells and their biodistribution depend on their surface modification. Here, we review the recent advances in modifying GNR surfaces with polyelectrolytes for biomedical applications. Major polyelectrolytes used to coat GNR surfaces over the past few years and the biocompatibility of polyelectrolyte-coated GNRs are discussed.

Design of hybrid nanovehicles for remotely triggered drug release: an overview

This review addresses the advantages of remote triggers, e.g. ultrasounds, near infrared light and alternating magnetic fields, the fabrication of the hybrid nanovehicles, the release mechanisms and the next challenges.

Self-illuminative cascade-reaction-driven anticancer therapeutic cassettes made of cooperatively interactive nanocomplexes

Therapeutic options based on near-infrared (NIR) wavelengths have attracted attention owing to in vivo lowest-background interventions and the development of several nano-architectures with localized surface plasmon resonance. Because of their limited tissue penetration, the clinical use of NIR light-driven treatments is not widespread; this technology is inapplicable to infection sites in the deeper areas of internal tissues. In this study, we demonstrate a self-illuminative therapeutic cassette able to exert anticancer effects via a series of enzymatic, chemical, and optical cooperative cascade reactions. It consists of (1) NIR-illuminative nanocomplexes and (2) NIR-sensitive therapeutic cassettes, which demonstrate a 60% chemically-induced killing effect in a prostate cancer model without external NIR irradiation. This technology can also be actively exploited as an imaging agent due to adaptation of a self-illuminating nanocomplex. Consequently, these novel therapeutic cassettes, which work not only as a powerful internal NIR stimulant, but also as a biological imaging platform, provide a new rational design concept for biomedical use.

Poly(N-vinylcaprolactam): a thermoresponsive macromolecule with promising future in biomedical field

Poly(N-vinylcaprolactam) (PNVCL) is a thermoresponsive and biocompatible polymer that raises an increasing interest in the biomedical area, especially in drug delivery systems (DDS) that include micelles, hydrogels, and hybrid particles. The thermoresponsiveness of PNVCL, used alone or in combination with other stimuli- responsive polymers or particles (pH, magnetic field, or chemicals), is often key in the loading and/or release process in these DDS. The renewed focus on this polymer, which is known for decades, is to a large extent due to recent progress in synthetic strategies. Especially, the advent of efficient controlled radical polymerization (CRP) methods for NVCL monomer gives now access to unprecedented well-defined NVCL-based copolymers with unique properties. This Review article addresses up-to-date synthetic aspects, biological features, and biomedical applications of the latest NVCL-containing systems.

Citrate-stabilized gold nanorods

Stable aqueous dispersions of citrate-stabilized gold nanorods (cit-GNRs) have been prepared in scalable fashion by surfactant exchange from cetyltrimethylammonium bromide (CTAB)-stabilized GNRs, using polystyrenesulfonate (PSS) as a detergent. The surfactant exchange process was monitored by infrared spectroscopy, surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopy (XPS). The latter established the quantitative displacement of CTAB (by PSS) and of PSS (by citrate). The Cit-GNRs are indefinitely stable at low ionic strength, and are conducive to further ligand exchange without loss of dispersion stability. The reliability of the surface exchange process supports the systematic analysis of ligand structure on the hydrodynamic size of GNRs, as described in a companion paper.

Photo-responsive polymeric micelles

Photo-responsive polymeric micelles have received increasing attention in both academic and industrial fields due to their efficient photo-sensitive nature and unique nanostructure. In view of the photo-reaction mechanism, photo-responsive polymeric micelles can be divided into five major types: (1) photoisomerization polymeric micelles, (2) photo-induced rearrangement polymeric micelles, (3) photocleavage polymeric micelles, (4) photo-induced crosslinkable polymeric micelles, and (5) photo-induced energy conversion polymeric micelles. This review highlights the recent advances of photo-responsive polymeric micelles, including the design, synthesis and applications in various biomedical fields. Especially, the influence of different photo-reaction mechanisms on the morphology, structure and properties of the polymeric micelles is emphasized. Finally, the possible future directions and perspectives in this emerging area are briefly discussed.

Graphene-based electroresponsive scaffolds as polymeric implants for on-demand drug delivery

Stimuli-responsive biomaterials have attracted significant attention in the field of polymeric implants designed as active scaffolds for on-demand drug delivery. Conventional porous scaffolds suffer from drawbacks such as molecular diffusion and material degradation, allowing in most cases only a zero-order drug release profile. The possibility of using external stimulation to trigger drug release is particularly enticing. In this paper, the fabrication of previously unreported graphene hydrogel hybrid electro-active scaffolds capable of controlled small molecule release is presented. Pristine ball-milled graphene sheets are incorporated into a three dimensional macroporous hydrogel matrix to obtain hybrid gels with enhanced mechanical, electrical, and thermal properties. These electroactive scaffolds demonstrate controlled drug release in a pulsatile fashion upon the ON/OFF application of low electrical voltages, at low graphene concentrations (0.2 mg mL(-1) ) and by maintaining their structural integrity. Moreover, the in vivo performance of these electroactive scaffolds to release drug molecules without any "resistive heating" is demonstrated. In this study, an illustration of how the heat dissipating properties of graphene can provide significant and previously unreported advantages in the design of electroresponsive hydrogels, able to maintain optimal functionality by overcoming adverse effects due to unwanted heating, is offered.