Theranostic gold-in-gold cage nanoparticles enable photothermal ablation and photoacoustic imaging in biofilm-associated infection models.

Biofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we described a complex structure of a dextran-coated gold-in-gold cage nanoparticle that enabled photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser could selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observed a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections, respectively. These effects were over 100 times greater than those seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We concluded that photothermal ablation using theranostic nanoparticles is a rapid, precise, and nontoxic method to detect and treat biofilm-associated infections.

A novel injectable radiopaque hydrogel with potent properties for multicolor CT imaging in the context of brain and cartilage regenerative therapy.

Cell therapy is promising to treat many conditions, including neurological and osteoarticular diseases. Encapsulation of cells within hydrogels facilitates cell delivery and can improve therapeutic effects. However, much work remains to be done to align treatment strategies with specific diseases. The development of imaging tools that enable monitoring cells and hydrogel independently is key to achieving this goal. Our objective herein is to longitudinally study an iodine-labeled hydrogel, incorporating gold-labeled stem cells, by bicolor CT imaging after in vivo injection in rodent brains or knees. To this aim, an injectable self-healing hyaluronic acid (HA) hydrogel with long-persistent radiopacity was formed by the covalent grafting of a clinical contrast agent on HA. The labeling conditions were tuned to achieve sufficient X-ray signal and to maintain the mechanical and self-healing properties as well as injectability of the original HA scaffold. The efficient delivery of both cells and hydrogel at the targeted sites was demonstrated by synchrotron K-edge subtraction-CT. The iodine labeling enabled to monitor the hydrogel biodistribution in vivo up to 3 days post-administration, which represents a technological first in the field of molecular CT imaging agents. This tool may foster the translation of combined cell-hydrogel therapies into the clinics.

Theranostic gold in a gold cage nanoparticle for photothermal ablation and photoacoustic imaging of skin and oral infections.

Biofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we describe a unique structure of dextran coated gold in a gold cage nanoparticle that enables photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser can selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observe a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections respectively. These effects were over 100 times greater than that seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We conclude that photothermal ablation using theranostic nanoparticles is a rapid, precise, and non-toxic method to detect and treat biofilm-associated infections.

Spectral Photon-Counting CT Imaging of Gold Nanoparticle Labelled Monocytes for Detection of Atherosclerosis: A Preclinical Study.

A key process in the development of atherosclerotic plaques is the recruitment of monocytes into the artery wall. Using spectral photon-counting computed tomography we examine whether monocyte deposition within the artery wall of ApoE-/- mouse can be detected. Primary mouse monocytes were labelled by incubating them with 15 nm gold nanoparticles coated with 11-mercaptoundecanoic acid The monocyte uptake of the particle was confirmed by electron microscopy of the cells before injection into 6-week-old apolipoprotein E deficient (ApoE-/-) mouse that had been fed with the Western diet for 10 weeks. Four days following injection, the mouse was sacrificed and imaged using a MARS spectral photon counting computed tomography scanner with a spectral range of 7 to 120 KeV with five energy bins. Imaging analysis showed the presence of X-ray dense material within the mouse aortic arch which was consistent with the spectral characteristic of gold rather than calcium. The imaging is interpreted as showing the deposition of gold nanoparticles containing monocytes within the mouse aorta. The results of our study determined that spectral photon-counting computed tomography could provide quantitative information about gold nanoparticles labelled monocytes in voxels of 90 × 90 × 90 µm3. The imaging was consistent with previous micro-CT and electron microscopy of mice using the same nanoparticles. This study demonstrates that spectral photon-counting computed tomography, using a MARS small bore scanner, can detect a fundamental atherogenic process within mouse models of atherogenesis. The present study demonstrates the feasibility of spectral photon-counting computed tomography as an emerging molecular imaging modality to detect atherosclerotic disease.

Novel Combination Treatment for Melanoma: FLASH Radiotherapy and Immunotherapy Delivered by a Radiopaque and Radiation Responsive Hydrogel.

Immunotherapies have become the standard treatment for melanoma. To further improve patient responses, combinations of immunotherapies and radiotherapy (RT) are being studied, since radiotherapies can potentially provide additional immune stimulation, in addition to direct antitumor effects. FLASH-RT is a novel, ultrahigh dose rate, radiation delivery approach, with the potential of at least equivalent tumor control efficacy and reduced damage to healthy tissue. However, the effects of combining FLASH-RT and immunotherapy have not been extensively studied in melanoma. Toll-like receptor (TLR) agonists, such as imiquimod (IMQ), are potent immunostimulatory agents, although their utility is limited due to poor solubility and systemic side effects. We therefore developed a novel combination therapy for melanoma consisting of IMQ delivered to the tumor via a radiopaque and radiation responsive hydrogel combined with FLASH-RT. We found that FLASH was able to effectively stimulate IMQ release from the hydrogel. In addition, we found that the combination of FLASH and released IMQ resulted in synergistic melanoma cell killing in vitro. The combination therapy reduced tumor growth compared to controls, enhanced survival, and resulted in remarkable enhancements in certain tumor cytokine levels. CT imaging allowed the hydrogel to be monitored in vivo. In addition, no adverse effects of the treatment were observed. Overall, this IMQ-gel and FLASH-RT combination may have potential as an improved treatment for melanoma and indicates that the interactions of FLASH-RT and TLR agonists merit further study.

Ytterbium Nanoparticle Contrast Agents for Conventional and Spectral Photon-Counting CT and Their Applications for Hydrogel Imaging.

Significant work has been done to develop nanoparticle contrast agents for computed tomography (CT), with a focus on identifying safer and more effective formulations. Contrast agents for spectral photon-counting computed tomography (SPCCT), a fast-growing imaging modality derived from conventional CT, have also recently gained considerable attention. In this study, we explored the synthesis of ultrasmall ytterbium nanoparticles (YbNP) and demonstrated that, potentially, they can be used as conventional CT and SPCCT contrast agents. These nanoparticles were tested in vitro for their cytotoxicity and contrast-generating properties with a variety of imaging systems. When scanned with conventional CT and SPCCT at clinically relevant energies, YbNP are significantly more attenuating than gold nanoparticles (AuNP), the contrast agents that have been most well studied. Furthermore, YbNP were studied for their potential application for labeling and monitoring hydrogels. The presence of the YbNP payload in hydrogels allowed for hydrogel localization and tracking in vivo. Additionally, the in vivo imaging results revealed that YbNP generate higher contrast when compared to AuNP used as a label. In summary, this is the first research study to examine ultrasmall YbNP as conventional CT and SPCCT contrast agents, as well as using them in a hydrogel system to make it radiopaque. These findings underscore YbNP's utility as CT and SPCCT contrast agents, as well as their potential for tracking hydrogels in vivo.

Renally Excretable Silver Telluride Nanoparticles as Contrast Agents for X-ray Imaging.

The use of nanoparticles in the biomedical field has gained much attention due to their applications in biomedical imaging, drug delivery, and therapeutics. Silver telluride nanoparticles (Ag2Te NPs) have been recently shown to be highly effective computed tomography (CT) and dual-energy mammography contrast agents with good stability and biocompatibility, as well as to have potential for many other biomedical purposes. Despite their numerous advantageous properties for diagnosis and treatment of disease, the clinical translation of Ag2Te NPs is dependent on achieving high levels of excretion, a limitation for many nanoparticle types. In this work, we have synthesized and characterized a library of Ag2Te NPs and identified conditions that led to 3 nm core size and were renally excretable. We found that these nanoparticles have good biocompatibility, strong X-ray contrast generation, and rapid renal clearance. Our CT data suggest that renal elimination of nanoparticles occurred within 2 h of administration. Moreover, biodistribution data indicate that 93% of the injected dose (%ID) has been excreted from the main organs in 24 h, 95% ID in 7 days, and 97% ID in 28 days with no signs of acute toxicity in the tissues studied under histological analysis. To our knowledge, this renal clearance is the best reported for Ag2Te NP, while being comparable to the highest renal clearance reported for any type of nanoparticle. Together, the results herein presented suggest the use of GSH-Ag2Te NPs as an X-ray contrast agent with the potential to be clinically translated in the future.

Effect of Nanoparticle Synthetic Conditions on Ligand Coating Integrity and Subsequent Nano-Biointeractions.

Most current nanoparticle formulations have relatively low clearance efficiency, which may hamper their likelihood for clinical translation. Herein, we sought to compare the clearance and cellular distribution profiles between sub-5 nm, renally-excretable silver sulfide nanoparticles (Ag2S-NPs) synthesized via either a bulk, high temperature, or a microfluidic, room temperature approach. We found that the thermolysis approach led to significant ligand degradation, but the surface coating shell was unaffected by the microfluidic synthesis. We demonstrated that the clearance was improved for Ag2S-NPs with intact ligands, with less uptake in the liver. Moreover, differential distribution in hepatic cells was observed, where Ag2S-NPs with degraded coatings tend to accumulate in Kupffer cells and those with intact coatings are more frequently found in hepatocytes. Therefore, understanding the impact of synthetic processes on ligand integrity and subsequent nano-biointeractions will aid in designing nanoparticle platforms with enhanced clearance and desired distribution profiles.

Novel Treatment for Glioblastoma Delivered by a Radiation Responsive and Radiopaque Hydrogel.

Successful treatment of glioblastoma (GBM) is hampered by primary tumor recurrence after surgical resection and poor prognosis, despite adjuvant radiotherapy and chemotherapy. In search of improved outcomes for this disease, quisinostat appeared as a lead compound in drug screening. A delivery system was devised for this drug and to exploit current clinical methodology: an injectable hydrogel, loaded with both the quisinostat drug and radiopaque gold nanoparticles (AuNP) as contrast agent, that can release these payloads as a response to radiation. This hydrogel grants high local drug concentrations, overcoming issues with current standards of care. Significant hydrogel degradation and quisinostat release were observed due to the radiation trigger, providing high in vitro anticancer activity. In vivo, the combination of radiotherapy and the radiation-induced delivery of quisinostat from the hydrogel, successfully inhibited tumor growth in a mice model bearing xenografted human GBM tumors with a total response rate of 67%. Long-term tolerability was observed after intratumoral injection of the quisinostat loaded hydrogel. The AuNP payload enabled precise image-guided radiation delivery and the monitoring of hydrogel degradation using computed tomography (CT). These exciting results highlight this hydrogel as a versatile imageable drug delivery platform that can be activated simultaneously to radiation therapy and potentially offers improved treatment for GBM.

Detecting and Monitoring Hydrogels with Medical Imaging.

Hydrogels, water-swollen polymer networks, are being applied to numerous biomedical applications, such as drug delivery and tissue engineering, due to their potential tunable rheologic properties, injectability into tissues, and encapsulation and release of therapeutics. Despite their promise, it is challenging to assess their properties in vivo and crucial information such as hydrogel retention at the site of administration and in situ degradation kinetics are often lacking. To address this, technologies to evaluate and track hydrogels in vivo with various imaging techniques have been developed in recent years, including hydrogels functionalized with contrast generating material that can be imaged with methods such as X-ray computed tomography (CT), magnetic resonance imaging (MRI), optical imaging, and nuclear imaging systems. In this review, we will discuss emerging approaches to label hydrogels for imaging, review the advantages and limitations of these imaging techniques, and highlight examples where such techniques have been implemented in biomedical applications.

Recent Advances in Molecular Imaging with Gold Nanoparticles.

Gold nanoparticles (AuNP) have been extensively developed as contrast agents, theranostic platforms, and probes for molecular imaging. This popularity has yielded a large number of AuNP designs that vary in size, shape, surface functionalization, and assembly, to match very closely the requirements for various imaging applications. Hence, AuNP based probes for molecular imaging allow the use of computed tomography (CT), fluorescence, and other forms of optical imaging, photoacoustic imaging (PAI), and magnetic resonance imaging (MRI), and other newer techniques. The unique physicochemical properties, biocompatibility, and highly developed chemistry of AuNP have facilitated breakthroughs in molecular imaging that allow the detection and imaging of physiological processes with high sensitivity and spatial resolution. In this Review, we summarize the recent advances in molecular imaging achieved using novel AuNP structures, cell tracking using AuNP, targeted AuNP for cancer imaging, and activatable AuNP probes. Finally, the perspectives and current limitations for the clinical translation of AuNP based probes are discussed.

Effect of Gold Nanoparticle Size on Their Properties as Contrast Agents for Computed Tomography.

Computed tomography (CT) is one of the most commonly used clinical imaging modalities. There have recently been many reports of novel contrast agents for CT imaging. In particular, the development of gold nanoparticles (AuNP) as CT contrast agents is a topic of intense interest. AuNP have favorable characteristics for this application such as high payloads of contrast generating material, strong X-ray attenuation, excellent biocompatibility, tailorable surface chemistry, and tunable sizes and shapes. However, there have been conflicting reports on the role of AuNP size on their contrast generation for CT. We therefore sought to extensively investigate the AuNP size-CT contrast relationship. In order to do this, we synthesized AuNP with sizes ranging from 4 to 152 nm and capped them with 5 kDa m-PEG. The contrast generation of AuNP of different sizes was investigated with three clinical CT, a spectral photon counting CT (SPCCT) and two micro CT systems. X-ray attenuation was quantified as attenuation rate in Hounsfield units per unit concentration (HU/mM). No statistically significant difference in CT contrast generation was found among different AuNP sizes via phantom imaging with any of the systems tested. Furthermore, in vivo imaging was performed in mice to provide insight into the effect of AuNP size on animal biodistribution at CT dose levels, which has not previously been explored. Both in vivo imaging and ex vivo analysis with inductively coupled plasma optical emission spectroscopy (ICP-OES) indicated that AuNP that are 15 nm or smaller have long blood circulation times, while larger AuNP accumulated in the liver and spleen more rapidly. Therefore, while we observed no AuNP size effect on CT contrast generation, there is a significant effect of size on AuNP diagnostic utility.

Wulff in a cage gold nanoparticles as contrast agents for computed tomography and photoacoustic imaging.

Nanostructures have potential for use in biomedical applications such as sensing, imaging, therapeutics, and drug delivery. Among nanomaterials, gold nanostructures are of considerable interest for biomedical research, owing to their bio-inertness, controllable surface chemistry, X-ray opacity, and optical properties. Gold nanocages are particularly attractive for imaging and therapeutic applications, because they strongly absorb light in the near infra-red region which has high light transmission in tissue. However, the X-ray attenuation of nanocages is relatively low due to their hollow structure. In this study, for the first time, we sought to combine the attractive optical properties of nanoshells with the high payloads of solid nanoparticles and investigated their biomedical applications. Here, we report the engineering of Wulff in a cage nanoparticles via converting gold Wulff-shaped seeds into gold-silver core-shell structures and then performing a galvanic replacement reaction. The structure of these nanoparticles was determined using transition electron microscopy. This morphological transformation of gold nanoparticles shaped as truncated octahedrons into a complex Wulff in a cage nanoparticles during the reaction resulted in extensive changes in their optical properties that made these unique structures a potential contrast agent for photoacoustic imaging. We found that the Wulff in a cage nanoparticles had no adverse effects on the viabilities of J774A.1, Renca, and HepG2 cells at any of the concentrations tested. In vitro and in vivo experiments showed robust signals in both photoacoustic imaging and computed tomography. To the best of our knowledge, this is the first report of Wulff in a cage nanoparticles serving as a platform for multiple imaging modalities. This unique multifunctional nanostructure, which integrates the competencies of both core and shell structures, allows their use as contrast agents for photoacoustic imaging, computed tomography and as a potential agent for photothermal therapy.

Effects of matrix metalloproteinase inhibitor doxycycline and CD147 antagonist peptide-9 on gallbladder carcinoma cell lines.

Gallbladder carcinoma is the most common and aggressive malignancy of the biliary tree and highly expresses CD147, which is closely related to disease prognosis in a variety of human cancers. Doxycycline exhibited anti-tumor properties in many cancer cells. CD147 antagonist peptide-9 is a polypeptide and can specifically bind to CD147. The effect of these two drugs on gallbladder cancer cells has not been studied. The aim of this study is to investigate the effect of doxycycline and antagonist peptide-9 on gallbladder carcinoma cells and the possible mechanism of inhibition on cancer cell of doxycycline. To investigate the effects of doxycycline and antagonist peptide-9 on gallbladder carcinoma cells (GBC-SD and SGC-996), cell proliferation, CD147 expression, and early-stage apoptosis rate were measured after treated with doxycycline. Matrix metalloproteinase-2 and matrix metalloproteinase-9 activities were measured after treated with different concentrations of doxycycline, antagonist peptide-9, and their combination. The results demonstrated that doxycycline inhibited cell proliferation, reduced CD147 expression level, and induced an early-stage apoptosis response in GBC-SD and SGC-996 cells. The matrix metalloproteinase-2 and matrix metalloproteinase-9 activities were inhibited by antagonist peptide-9 and doxycycline, and the inhibitory effects were enhanced by combined drugs in gallbladder carcinoma cell lines. Taken together, doxycycline showed inhibitory effects on gallbladder carcinoma cell lines and reduced the expression of CD147, and this may be the mechanism by which doxycycline inhibits cancer cells. This study provides new information and tries to implement the design of adjuvant therapy method for gallbladder carcinoma.

Clinical effect of ablative fractional laser-assisted topical anesthesia on human skin: A randomized pilot study.

BACKGROUND AND OBJECTIVES: Most topical medications need a long time to penetrate into the skin owing to the stratum corneum (SC) barrier. The fractional erbium-doped yttrium aluminum garnet (Er:YAG) laser has the ability to disrupt the SC and assist in the delivery of topical drugs to penetrate into the skin. This study was intended to determine whether pretreatment with a painless fractional Er:YAG laser could assist transdermal delivery of topical anesthesia. MATERIALS AND METHODS: In 22 healthy female subjects, three 4 × 3 cm regions on the right forearm were randomized to: fractional laser plus topical lidocaine cream (Group LaserAnes), sham irradiation plus topical anesthesia (Group Anes), and sham irradiation plus sham anesthesia (Group Con). After 5 minutes, each site was treated with yttrium scandium gallium garnet laser to evaluate the pain sensation using the visual analog scale. RESULTS: The average pain scores of Group LaserAnes, Group Anes, and Group Con are 3.74 ± 1.93, 4.90 ± 2.09, and 5.19 ± 2.15, respectively. The pain score of Group LaserAnes has a 25.57% reduction compared to Group Anes (p < 0.001) and a 28.70% reduction compared to Group Con (p < 0.001). There is no significant pain reduction for Group Anes compared with Group Con (p = 0.094). CONCLUSIONS: Pretreatment using fractional Er:YAG laser before topicals might be an effective method for drug delivery.

cOSPREY: A Cloud-Based Distributed Algorithm for Large-Scale Computational Protein Design.

Finding the global minimum energy conformation (GMEC) of a huge combinatorial search space is the key challenge in computational protein design (CPD) problems. Traditional algorithms lack a scalable and efficient distributed design scheme, preventing researchers from taking full advantage of current cloud infrastructures. We design cloud OSPREY (cOSPREY), an extension to a widely used protein design software OSPREY, to allow the original design framework to scale to the commercial cloud infrastructures. We propose several novel designs to integrate both algorithm and system optimizations, such as GMEC-specific pruning, state search partitioning, asynchronous algorithm state sharing, and fault tolerance. We evaluate cOSPREY on three different cloud platforms using different technologies and show that it can solve a number of large-scale protein design problems that have not been possible with previous approaches.