From Visible to Near-Infrared Light-Triggered Photochromism: Negative Photochromism.

Photochromic compounds, whose key molecular properties can be effectively modulated by light irradiation, have attracted significant attention for their potential applications in various research fields. The restriction of photoisomerization coloration induced by ultraviolet light limits their applications in the biomedical field and some other fields. Negative photochromism, wherein a relatively stable colored isomer transforms to a colorless metastable isomer under low-energy light irradiation, offers advantages in applications within materials science and life science. This review provides a summary of negatively photochromic compounds based on different molecular skeletons. Their corresponding design strategies and photochromic properties are presented to provide practical guidelines for future investigations. Negatively photochromic compounds can effectively expand the range of photochromic switches for future applications, offering unique properties such as responsiveness to visible to near-infrared light.

Silicene/poly(N-isopropylacrylamide) smart hydrogels as remote light-controlled switches.

Smart hydrogels with good flexibility and biocompatibility have been widely used. The common near-infrared (NIR) photothermal agents are facing a trade-off between good photothermal-conversion efficiency and high biocompatibility. Therefore, developing new metal-free photothermal agents with low cost, high biocompatibility and excellent phase stability is still in urgent need. In this study, we successfully combined poly(N-isopropylacrylamide) (PNIPAM) with the two-dimensional (2D) silicene nanosheets via the in situ polymerization method. Attributed to the thermal-responsive nature of PNIPAM and the excellent photothermal properties of 2D silicene, the obtained silicene/PNIPAM composite hydrogels exhibited dual thermal and NIR responsive properties. This smart hydrogel showed rapid, reversible and repeatable NIR light-responsive behaviors. The volume of this smart hydrogels can shrink significantly under NIR irradiation and recover to its original size without the NIR irradiation. Remote near-infrared light-controlled microfluidic pipelines and electronic switches based on obtained silicene/PNIPAM composite hydrogels were also demonstrated. This work significantly broadens the application prospects of silicene-based hydrogels in remote light-controlled devices.

Treatment of microvascular invasion in hepatocellular carcinoma with drug-loaded nanocomposite platform under synergistic effect of magnetic field/near-infrared light.

Despite progress in clinical treatment, microvascular invasion (MVI) remains a major factor for frequent recurrence and metastasis of hepatocellular carcinoma (HCC) after liver resection and surgery. Thus, this study constructed a target nanoplatform (αCD97-USPIO-Au-DDP) with magnetic field/near-infrared (NIR) light response using ultrasmall superparamagnetic iron oxide-gold nanoporous spheres (USPIO-Au) as multifunctional nanocarrier. Anticancer drug cisplatin (DDP) was loaded, and specifically expressed CD97 protein in MVI was taken as the therapeutic target. The αCD97-USPIO-Au-DDP showed favorable photothermal and stable properties under the NIR light at 808 nm wavelength. As suggested by in vitro and in vivo research, this composite nanopreparation could effectively reduce damage to normal organs and showed good biocompatibility. Excellent magnetic targeting function of nanocarrier and modification of αCD97 strengthened accumulation of composite nanodrug in tumor to inhibit tumor growth. This system may have important ramifications for treatment of MVI in HCC.

Optimization of Preparation Technology of Near-infrared Light Response-based Doxorubicin Hydrochloride Nano-liposomes / 中国药房

OBJECTIVE： To establish a methaod for content determination of doxorubicin hydrochloride nano-liposomes， and to optimize its preparation technology. METHODS： The contents of doxorubicin hydrochloride nano-liposomes was determined by UV spectrophotometry. The membrane dispersion method was used to prepare doxorubicin hydrochloride nano-liposomes. Using particle size， encapsulation efficiency and drug-loading amount as indexes， the weight ratio of phospholipid to drug （mg/mg）， the weight ratio of phospholipid to cholesterol （mg/mg） and ultrasonic time （min） as factors， central composite design-response surface methodology was used to optimize the preparation technology. The photothermal conversion effect of doxorubicin hydrochloride nano-liposomes was investigated by near infrared irradiation. RESULTS： The linear range of doxorubicin hydrochloride were 1.01-16.16 μg/mL（r＝0.999 7）； precision， stability and reproducibility tests were all in line with the requirments of Chinese Pharmacopoeia. The optimal preparation technology included that the weight ratio of phospholipid to drug was 13.30 ∶ 1（mg/mg）； the weight ratio of phospholipid to cholesterol was 4.09 ∶ 1 （mg/mg）； the ultrasonic time was 10 min. Under this technology， the particle size and drug-loading amount of doxorubicin hydrochloride nano-liposomes were （200.5±25.1） nm and （11.02±0.20）％， relative errors of which to predicted value （196.3 nm， 10.68％） were 1.82％ and 1.63％. The consistency between measured value and predicted value was good. Doxorubicin hydrochloride nano-liposomes exhibited concentration- dependent and time-dependent photothermal conversion characteristics under near infrared irradiation at 808 nm. CONCLUSIONS： Established method is simple and good accuracy. The optimized preparation technology is simple and feasible.

Photoactivatable RNAi for cancer gene therapy triggered by near-infrared-irradiated single-walled carbon nanotubes.

The efficacy of RNA interference (RNAi)-based cancer gene therapy is limited by its unexpected side effects, thus necessitating a strategy to precisely trigger conditional gene knockdown. In this study, we engineered a novel photoactivatable RNAi system, named as polyetherimide-modified single-wall carbon nanotube (PEI-SWNT)/pHSP-shT, that enables optogenetic control of targeted gene suppression in tumor cells. PEI-SWNT/pHSP-shT comprises a stimulus-responsive nanocarrier (PEI-SWNT), and an Hsp70B'-promoter-driven RNAi vector (pHSP-shT). In response to near-infrared (NIR) light irradiation, heating of PEI-SWNT in breast MCF-7 cells triggered gene knockdown targeting human telomerase reverse transcriptase through RNAi, with the gene-knockdown activity capable of being switched off by extinguishing the NIR. Furthermore, we demonstrated that the photoactivatable RNAi system exhibited higher antitumor activity by combining gene therapy and photothermal therapy, both in vitro and in vivo. Optogenetic control of RNAi based on an NIR-activated nanocarrier will potentially facilitate improved understanding of molecular-targeted gene therapy in human malignant tumors.

Near-Infrared Light-Responsive Poly(N-isopropylacrylamide)/Graphene Oxide Nanocomposite Hydrogels with Ultrahigh Tensibility.

Novel near-infrared (NIR) light-responsive poly(N-isopropylacrylamide)/graphene oxide (PNIPAM-GO) nanocomposite hydrogels with ultrahigh tensibility are prepared by incorporating sparse chemical cross-linking of small molecules with physical cross-linking of graphene oxide (GO) nanosheets. Combination of the GO nanosheets and thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) polymeric networks provides the hydrogels with an excellent NIR light-responsive property. The ultrahigh tensibility of PNIPAM-GO nanocomposite hydrogels is achieved by simply using a very low concentration of N,N'-methylenebis(acrylamide) (BIS) molecules as chemical cross-linkers to generate a relatively homogeneous structure with flexible long polymer chains and rare chemically cross-linked dense clusters. Moreover, the oxidized groups of GO nanosheets enable the formation of a hydrogen bond interaction with the amide groups of PNIPAM chains, which could physically cross-link the PNIPAM chains to increase the toughness of the hydrogel networks. The prepared PNIPAM-GO nanocomposite hydrogels with ultrahigh tensibility exhibit rapid, reversible, and repeatable NIR light-responsive properties, which are highly promising for fabricating remote light-controlled devices, smart actuators, artificial muscles, and so on.