Light-Activable On-Demand Release of Nano-Antibiotic Platforms for Precise Synergy of Thermochemotherapy on Periodontitis.

The overprescription and improper use of antibiotics have contributed to the evolution of bacterial resistance, making it urgent to develop alternative therapies and agents with better efficacy as well as less toxicity to combat bacterial infections and keep new resistance from developing. In this work, a novel light-activable nano-antibiotic platform (TC-PCM@GNC-PND) was constructed by the incorporation of gold nanocages (GNC) and two thermosensitive gatekeepers, phase-change materials (PCM) and thermosensitive polymer poly(N-isopropylacrylamide-co-diethylaminoethyl methacrylate) (PND), to realize precisely the synergy of photothermal and antimicrobial drugs. GNC exhibits an excellent photothermal effect owing to its strong absorbance in the near-infrared (NIR) region, and hollow interiors make it a favorable vehicle for loading various antibiotics such as tetracycline (TC). The release of the encapsulated drugs could be precisely controlled by NIR light through the dual thermosensitive interaction of liquid-solid transition of PCM and coil-granule transition of PND, improving efficacy and alleviating side effects with on-demand drug release. The thermosensitive hydrogel was formed in situ upon application with body temperature, enhancing retention of the antimicrobial agent in local infectious sites. Highly effective ablation of bacteria is achieved both in vitro and in periodontitis models with little toxicity owing to the synergy of photothermal effects and chemotherapeutic drug release induced by NIR. This study could provide guidance for the design of antibacterial materials and shed substantial light on synergistic treatment.

Calorimetric lateral flow immunoassay detection platform based on the photothermal effect of gold nanocages with high sensitivity, specificity, and accuracy.

BACKGROUND: Lateral flow assays (LFA) play an increasingly important role in the rapid detection of various pathogens, pollutants, and toxins. PURPOSE: To overcome the drawbacks of low sensitivity and poor quantification in LFA, we developed a new calorimetric LFA (CLFA) using gold nanocages (GNCs) due to their high photothermal conversion efficiency, good stability of photophysical properties, and stronger penetrating ability of NIR light. METHODS: Thiol-polyethylene glycol-succinyl imide ester (HS-PEG-NHS) was modified onto GNCs, and the complex was conjugated with an antibody. Subsequently, the antibody-conjugated GNCs were analyzed by UV/Vis spectrophotometer, transmission electron microscope, high-resolution transmission electron microscope with energy dispersive spectrometer, dynamic light scattering instrument, and Atom force microscope. The GNC-based CLFA of alpha-fetoprotein (AFP) and zearalenone (ZEN), a food toxin, required nitrocellulose strips, a NIR laser source, and an infrared camera. RESULTS: The GNC-labeled CLFA platform technique exhibited detection sensitivity, qualitative specificity, and quantitative accuracy. The superior performance of the technique was evident both in sandwich format detection of biomacromolecules (eg, AFP protein) or competitive format detection of small molecules (eg, ZEN). After optimizing various test parameters, GNC-labeled CLFA provided ca. 5-6-fold enhanced sensitivity, higher correlativity (R 2>0.99), and more favorable recovery (82-115%) when compared with visual LFA. CONCLUSION: GNC-labeled CLFA may be a promising detection platform with high sensitivity, specificity, and precision.

pH- and photothermal-driven multistage delivery nanoplatform for overcoming cancer drug resistance.

Reversing multidrug resistance (MDR) remains a big challenge in cancer therapy. Combining the hyperthermia and chemotherapy is a promising strategy for efficient cancer treatment with MDR reversal. Gold nanocages (GNCs) are an ideal photothermal (PTT)-chemotherapy integration platform due to their good photothermal conversion efficiency and the unique hollow interiors. However, insufficient tumor cell internalization and in vivo premature drug leakage restrict the anticancer activity of GNCs-based drug delivery systems. Methods: pH low insertion peptide (pHLIP)- and thermoresponsive poly(di(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) methyl ether methacrylate) polymer-conjugated GNCs were rationally constructed to load anticancer drug doxorubicin (DOX@pPGNCs). Tumor acidic environment-responsive tumor cell internalization, and near-infrared (NIR) laser-induced tumor accumulation, penetration and on-demand drug release were systematically examined. Results: DOX@pPGNCs display good photothermal efficacy and thermoresponsive property. NIR laser irradiations at the tumor site significantly enhance tumor accumulation and penetration. Once DOX@pPGNCs reach the tumor site, the conformational transformation of pHLIP at the acidic tumor microenvironment contributes to the enhanced cellular internalization. Furthermore, NIR laser-triggered photothermal effects induce the shrinkage of thermoresponsive polymer, resulting in the opening of the pores of GNCs and a rapid intracellular DOX release to the nuclei. DOX@pPGNCs exhibit synergistic antitumor effect with MDR reversal in vitro and in vivo. Conclusion: DOX@pPGNCs present strong potential to overcome MDR in cancer.

A Biomimetic Gold Nanocages-Based Nanoplatform for Efficient Tumor Ablation and Reduced Inflammation.

Gold nanocages (AuNCs), with high photothermal conversion efficiency and unique hollow interiors, have become a promising nanoplatform for synergistic phototheraml therapy (PTT)-chemotherapy. However, the insufficient tumor targeting, in vivo premature drug leakage and low drug loading efficiency responsible for the spatial-temporal un-synchronization of PTT-chemotherapy, as well as inflammatory response might compromise the anticancer treatment of AuNCs-based drug delivery systems. Methods: Cancer cell membrane (CCM)-coated AuNCs were developed to load anticancer drug doxorubicin (DOX@CAuNCs) by transmembrane ammonium sulfate gradient method. In vitro and in vivo analysis, including characterization, macrophage phagocytosis and tumor targeting capacity, near-infrared (NIR) laser-induced drug release, antitumor efficacy and inflammation response were systematically performed. Results: DOX@CAuNCs showed a high DOX loading capacity and on-demand NIR laser-triggered DOX release compared with CAuNCs passively loading DOX by electrostatic adsorption, a commonly used method to load drug to AuNCs. Meanwhile, in view of the properties of CCM coated on AuNCs, DOX@CAuNCs exhibited decreased macrophage phagocytosis, prolonged blood circulation and enhanced internalization by cancer cells, generating preferable tumor targeting ability. With these integrated advantages, DOX@CAuNCs demonstrated highly efficient and precise spatial-temporal synchronization of PTT-chemotherapy, achieving complete tumor ablation with no obvious side effects. Besides, coating with CCM significantly alleviated AuNCs-induced inflammatory response. Conclusion: This biomimetic AuNCs-based platform might be a prospective drug delivery system for precision PTT and chemotherapy, acquiring desired cancer treatment efficacy and low inflammatory response.

Precise synchronization of hyperthermia-chemotherapy: photothermally induced on-demand release from injectable hydrogels of gold nanocages.

Though a therapeutic sequence plays a key role in tumor therapy, little attention has been paid to its influence on multimodal combined therapy. Herein, we developed gold nanocages (GNC@PNA-hls) decorated with two kinds of temperature sensitive p(N-isopropyl-acrylamide-acrylic acid) copolymers (PNA-hs and PNA-ls) for precise antitumor coordination of thermo-chemotherapy. Doxorubicin-loaded GNC@PNA-hls (Dox-GNC@PNA-hls) showed a steady photothermally induced on-demand release under multiple near-infrared (NIR) irradiations. In vitro evaluations indicated that concurrent thermo-chemotherapy treatments (Dox - L) showed the best antitumor effect, compared with the sequence of either doxorubicin treatment followed by NIR radiation (Dox + L) or NIR radiation followed by doxorubicin treatment (L + Dox). The in vivo antitumor efficacy also indicated that the tumor volume was totally suppressed (ca. 0.14 cm3) by the treatment of Dox-GNC@PNA-hls with NIR radiation for 14 days. These results indicated that Dox-GNC@PNA-hls could achieve precise synchronization between hyperthermia and chemotherapy, and effectively enhance their antitumor efficacy.

Cisplatin-directed coordination-crosslinking nanogels with thermo/pH-sensitive triblock polymers: improvement on chemotherapic efficacy via sustained release and drug retention.

To realize the sustained release and long-term intratumoural retention of water-soluble cisplatin, thermo/pH-sensitive cisplatin-directed coordination-crosslinking nanogels (Pt-PNA) were developed via the coordination bonds of Pt-carboxyl groups. As the coordination ratio (CR) of the Pt-carboxyl bonds increased from 5% to 35%, the sizes of the Pt-PNA nanogels decreased from 999 nm to 167 nm, and their zeta potentials increased from -35 mV to -13 mV. Only through a simple mixing of cisplatin and PNAs, the entrapment efficiencies (EEs) of the Pt-PNA nanogels reached near 100% (>90%), and the drug-loading amounts (DLs) of cisplatin could achieve up to 25.5 ± 0.1%. For water-soluble cisplatin, Pt-PNA nanogels exhibited a sustained release for as long as 5 days. The thermo/pH-sensitive sol-gel phase-transition behaviour of the Pt-PNA nanogels were investigated via inverting-vial and rheological methods. Platinum elemental analysis indicated that the Pt-PNA nanogels showed a much stronger ability of cisplatin retention in tumours than free cisplatin. The platinum content in a tumour treated by the Pt-PNA nanogels was far higher than that by free cisplatin: 200.7 ± 63.6 µg vs. 82.7 ± 26.8 µg at the 1st day, or 118.9 ± 35.2 µg vs. 18.5 ± 9.4 µg at the 14th day. The evaluation of the in vivo antitumour efficacy indicated that only after a single dose of Pt-PNA nanogels, the tumour volume continuously decreased to 0.73 ± 0.07 times that of the original tumour volume (OTV) for 14 days; however, it rapidly increased by 3.37 ± 0.82, 8.01 ± 0.53 and 9.25 ± 1.85 times that of the OTV with the same dose of free cisplatin, PNA, and NS, respectively. Some preliminary evaluations of the biocompatibility indicated that the toxic side effects of cisplatin could be greatly improved via cisplatin-directed coordination-crosslinking with PNA. As a result, Pt-PNA nanogels could likely become a promising versatile strategy for improving antitumour efficacy and reducing the toxicity and size effects of platinum-based drugs, and they could also be developed as promising nanomedicines for regional chemotherapy.

Temperature sensitive p(N-isopropylacrylamide-co-acrylic acid) modified gold nanoparticles for trans-arterial embolization and angiography.

Temperature sensitive p(N-isopropylacrylamide-co-acrylic acid) modified gold nanoparticles (GNP@PNA) were prepared via coordination bonding between gold and sulfur elements. Their diameter and zeta potential were 86 nm and -26.2 mV at 25 °C, and 47 nm and -30.5 mV at 37 °C respectively. Thermogravimetric characterization of GNP@PNA indicated that the PNA shell and the GNP core accounted for 19.2 wt% and 78.2 wt%, namely ca. 70-80 chains of PNA were combined on the surface of one GNP nanoparticle. GNP@PNA showed much better X-ray attenuation ability, ca. 1.6-3.3 times higher than that of Omnipaque. In addition, the temperature sensitive sol-gel transition of GNP@PNA dispersions could realize the so-called "in situ casting" embolization from tumoral aorta to peripheral arteries, and improve their angiographic ability owing to the inhibition against GNP aggregation via gelation. Renal artery embolization on normal rabbits and TAE on VX2 tumor-bearing rabbits indicated that GNP@PNA achieved better embolization for longer times than Ivalon and Lipiodol. Excellent biocompatibility of GNP@PNA dispersions was also observed via the evaluation of cytotoxicity, hemolysis and hepatorenal function.

Doxorubicin-induced co-assembling nanomedicines with temperature-sensitive acidic polymer and their in-situ-forming hydrogels for intratumoral administration.

Doxorubicin (DOX)-induced co-assembling nanomedicines (D-PNAx) with temperature-sensitive PNAx triblock polymers have been developed for regional chemotherapy against liver cancer via intratumoral administration in the present work. Owing to the formation of insoluble DOX carboxylate, D-PNAx nanomedicines showed high drug-loading and entrapment efficacy via a simple mixing of doxorubicin hydrochloride and PNAx polymers. The sustained releasing profile of D-PNA100 nanomedicines indicated that only 9.4% of DOX was released within 1day, and 60% was released during 10days. Based on DOX-induced co-assembling behavior and their temperature sensitive in-situ-forming hydrogels, D-PNA100 nanomedicines showed excellent antitumor activity against H22 tumor using intratumoral administration. In contrast to that by free DOX solution (1.13±0.04 times at 9days) and blank PNA100 (2.11±0.34 times), the tumor volume treated by D-PNA100 had been falling to only 0.77±0.13 times of original tumor volume throughout the experimental period. In vivo biodistribution of DOX indicated that D-PNA100 nanomedicines exhibited much stronger DOX retention in tumor tissues than free DOX solution via intratumoral injection. D-PNA100 nanomedicines were hopeful to be developed as new temperature sensitive in-situ-forming hydrogels via i.t. injection for regional chemotherapy.

Antibacterial properties and mechanisms of gold-silver nanocages.

Despite the number of antibiotics used in routine clinical practice, bacterial infections continue to be one of the most important challenges faced in humans. The main concerns arise from the continuing emergence of antibiotic-resistant bacteria and the difficulties faced with the pharmaceutical development of new antibiotics. Thus, advancements in the avenue of novel antibacterial agents are essential. In this study, gold (Au) was combined with silver (Ag), a well-known antibacterial material, to form silver nanoparticles producing a gold-silver alloy structure with hollow interiors and porous walls (gold-silver nanocage). This novel material was promising in antibacterial applications due to its better biocompatibility than Ag nanoparticles, potential in photothermal effects and drug delivery ability. The gold-silver nanocage was then tested for its antibacterial properties and the mechanism involved leading to its antibacterial properties. This study confirms that this novel gold-silver nanocage has broad-spectrum antibacterial properties exerting its effects through the destruction of the cell membrane, production of reactive oxygen species (ROS) and induction of cell apoptosis. Therefore, we introduce a novel gold-silver nanocage that serves as a potential nanocarrier for the future delivery of antibiotics.

The stimuli-responsive multiphase behavior of core-shell nanogels with opposite charges and their potential application in in situ gelling system.

Concentrated p(N-isopropylacrylamide) (PNIPAM) nanogel dispersions exhibited rich temperature-sensitive sol-gel phase transition behavior. In the present work, the influence of electrostatic forces between nanogel particles, including attraction and repulsion, on the sol-gel phase transition behavior of PNIPAM nanogel dispersions has been studied. Both oppositely charged nanogels with core-shell structures (NIA and PND nanogels) were synthesized, and their shell charges were calculated to -0.33 and 0.082 mmol/g by potentiometric titration method. When mixed with various ratio of negative and positive charge (NC value), the resultant mixture dispersions of NIA and PND nanogel (OCNs) exhibited different aggregating behavior from NIA and PND nanogels. OCN-e aggregates (NC value=1/4), which exhibited temperature-independence of electric neutrality, had the maximum size, about 1.9-2.2 times larger than NIA or PND nanogels. Concentrated OCN-e dispersions exhibited stronger ability to form shrunken gel. Its CGC was about 2.0 wt%, 4-times lower than that of NIA and PND nanogels (about 8.0 wt%). In vitro and in vivo gelling results indicated that OCN-e aggregates could form free-standing gel with good mechanical strength, and were promising to be developed as new in situ gelling system.

The studies about doxorubicin-loaded p(N-isopropyl-acrylamide-co-butyl methylacrylate) temperature-sensitive nanogel dispersions on the application in TACE therapies for rabbit VX2 liver tumor.

Transarterial chemo-embolization (TACE), which combined embolization therapy and chemotherapy, has become the most widely used treatment for unresectable liver cancer. Blood-vessel-embolic materials play key role on TACE. In the present work, doxorubicin-loaded p(N-isopropylacrylamide-co-butyl methylacrylate) nanogels-iohexol dispersions (IBi-D) were reported firstly for TACE therapy to liver cancer. Using inverting-vial method, IBi-D dispersions showed three phases (swollen gel, flowable sol and shrunken gel) as temperature increased. Although Dox had little effect on the CGTs between flowable and shrunken gel, the rheological properties of IBi-D dispersions could greatly improved by Dox. A sustained Dox-release, which was necessary in TACE therapy, was found from IBi-D dispersions in the eluting medium of PBS buffers. The studies about renal artery embolization of normal rabbits indicated that IBi-D dispersions showed good properties in embolizing all kinds of renal arteries (including peripheral, small and large arteries) by controlling their injecting dosages. Angiography and medical evaluation indicated that TACE therapy of IBi-D dispersions has better efficacy on rabbit VX2 liver tumors than TAC treatment of free Dox and TAE treatment of IBi dispersions.

Temperature-sensitive fluorescent organic nanoparticles with aggregation-induced emission for long-term cellular tracing.

Temperature-sensitive organic nanoparticles with AIE effect were assembled in water from tetraphenylethene-based poly(N-isopropylacrylamide) (TPE-PNIPAM), which was synthesized by ATRP using TPE derivative as initiator. The size and fluorescence of TPE-PNIPAM nanoparticles can be tuned by varying the temperature. These nanoparticles can be internalized readily by HeLa cells and can be used as long-term tracer in live cells to be retained for as long as seven passages.

The studies on highly concentrated complex dispersions of gold nanoparticles and temperature-sensitive nanogels and their application as new blood-vessel-embolic materials with high-resolution angiography.

Recently temperature sensitive polymers have been developed as novel embolization materials. However, their flowability and embolization have been seriously impacted by iodine-based X-ray contrast agents. In order to resolve the drawbacks of these contrast agents, highly concentrated complex (HCC) dispersions of gold nanoparticles (GNPs) with p(N-isopropylacrylamide-co-butyl methylacrylate) (PIB) nanogels were developed as new blood-vessel-embolic materials with high-resolution angiography. Although GNPs have better X-ray attenuation than iodinated compounds, their poor dispersion stability limits their application in digital subtraction angiography (DSA). HCC dispersions show excellent X-ray attenuation ability which is 2.6 times higher than Omnipaque at 0.31 mol L-1. This can be attributed to the fact that the sol-gel transition of nanogel dispersions improves the colloid stability of GNPs. In the two sol-gel transition temperatures (Tg-s and T's-g) of nanogel dispersions, GNPs have no influence on T's-g, and a great influence on Tg-s. The in vivo experimental data indicate that HCC dispersions show high angiographic ability and good blood-vessel embolization, and can be used for postoperative examination for long periods owing to the entrapment of GNPs into the embolic sites. The HCC dispersions have potential to be developed as new blood-vessel-embolic materials with high-resolution angiography.