Photodynamic therapy (PDT) is a clinically-approved cancer treatment that is based on production of cytotoxic reactive oxygen species to induce cell death. However, its efficiency depends on distribution of photosensitizer (PS) and depth of light penetration through the tissues. Tendency of pathological cancer tissues to exhibit lower pH than healthy tissues inspired us to explore dual-targeted pH-activatable photosensitizers based on tunable near-infrared (NIR) boron-dipyrromethene (BODIPY) dyes. Our BODIPY PSs were designed to carry three main attributes: (i) biotin or cRGD peptide as an effective cancer cell targeting unit, (ii) amino moiety that is protonated in acidic (pH <6.5) conditions for pH-activation of the PS based on photoinduced electron transfer (PET) and (iii) hydrophilic groups enhancing the water solubility of very hydrophobic BODIPY dyes. Illumination of such compounds with suitable light (>640nm) allowed for high phototoxicity against HeLa (αvβ3 integrin and biotin receptor positive) and A549 (biotin receptor positive) cells compared to healthy MRC-5 (biotin negative) cells. Moreover, no dark toxicity was observed on selected cell lines (>10 μM) providing promising photosensitizers for tumour-targeted photodynamic therapy.

Porous poly (lactic-co-glycolic acid)/β-tricalcium phosphate/Icaritin (PLGA/β-TCP/ICT, PTI) scaffold is a tissue engineering scaffold based on PLGA/β-TCP containing Icaritin, the main active ingredient of the Chinese medicine Epimedium. Due to its excellent mechanical properties and osteogenic effect, PTI scaffold has the potential to promote bone defect repair. However, the release of ICT from the scaffolds is difficult to control. In this study, we constructed Ti3C2Tx@PLGA/ICT microspheres (TIM) and evaluated their characterization as well as ICT release under near-infrared (NIR) irradiation. We utilized TIM to modify the PT scaffold and performed biological experiments. First, we cultured rat bone marrow mesenchymal stem cells on the scaffold to assess biocompatibility and osteogenic potential under on-demand NIR irradiation. Subsequently, to evaluate the osteogenic properties of TIM-modified scaffold in vivo, the scaffold was implanted into a femoral condyle defect model. TIM have excellent drug-loading capacity and encapsulation efficiency for ICT, and the incorporation of Ti3C2Tx endows TIM with photothermal conversion capability. Under 0.90 W cm-2 NIR irradiation, the temperature of TIM maintained at 42.0 ± 0.5°C and the release of ICT was accelerated. Furthermore, while retaining its original properties, the TIM-modified scaffold was biocompatible and could promote cell proliferation, osteogenic differentiation, and biomineralization in vitro, as well as the osteogenesis and osseointegration in vivo, and its effect was further enhanced through the modulation of ICT release under NIR irradiation. In summary, TIM-modified scaffold has the potential to be applied in bone defects repairing.

Conjugated polymers (CPs)-based near-infrared phototheranostics are receiving increasing attention due to their high molar extinction coefficient, wide emission wavelength, easy preparation and excellent biocompatibility. Herein, several new conjugated polymers with D2-D1-A structures were easily prepared through one-pot coupling using triphenylamine (D2) as well as thiophenes (D1) as electron donors and benzothiadiazole (A) as electron acceptors. Interesting, their optical performance and power conversion efficiency could be tuned by side chains on thiophenes (D1). The introduction of ethylenedioxy into D1 as side chain significantly improves fluorescence imaging brightness, photothermal conversion efficiency and hydrophilicity, and extends emission wavelength, which are beneficial for phototheranostic. The side chain modification provides new opportunity to design efficient phototheranostics without construction new fluorescent skeletons.

Broadband near-infrared (NIR) phosphors are crucial components of NIR phosphor-converted light-emitting diode (pc-LED) sources for various smart spectroscopy applications. However, developing an efficient, tunable, and inexpensive broadband NIR phosphor with sufficient spectral coverage remains a great challenge. In this work, a cubic phosphate K2AlTi(PO4)3 with highly structural rigidity was chosen as host material for Cr3+ substitution to create an efficient NIR emission. Synthesizing this compound, the obtained material exhibits a broadband NIR emission covering 700-1200 nm with a peak wavelength ranging from 820 to 860 nm depending on the Cr3+ substituting concentration. The Cr3+ concentration optimized sample possesses a photoluminescence quantum yield (PLQY) of 76.4% with an emission peak centered at 857 nm and a full width at half-maximum (fwhm) of 184 nm under 464 nm exaction, demonstrating an efficient and relatively long-wavelength NIR emission with wide spectral coverage. This broadband NIR emission is mainly derived from a single kind of emission center deduced from spectral analysis, luminescence dynamics, and first-principle calculations. Using this material, the fabricated NIR pc-LED device presents an excellent NIR output power and NIR photoelectric conversion efficiency, making this material attractive in practical applications of night-vision and bioimaging. Therefore, this work not only provides a broadband NIR material with superiorities of low cost, high efficiency, wide-range tunability, wide spectral coverage, and relatively long-wavelength NIR emission for spectroscopy applications but also highlights some clues to discover this kind of materials.

A series of fluorescent molecules with 1,1-dimethylnaphthalene-2(1H)-one as the core were synthesized to overcome aggregation quenching and emit bright green fluorescence. The low molecular weight of these molecules led to them to smoothly pass through the cell membrane and penetrate deep into the nucleus to emit the corresponding fluorescence. Among them, NC-4-Br and NC-5-3O have good optical and in vitro properties and showed potential for use as fluorescent probes.

We investigated the deoxyribonucleic acid (DNA) damage induced by laser filamentation, which was generated by focusing femtosecond near-infrared Ti:Sapphire laser light in water at several repetition rates ranging from 1000 Hz to 10 Hz. Using plasmid DNA (pUC19), the single-strand break, double-strand break, nucleobase lesions, and the fragmented DNA were analyzed and quantified by agarose gel electrophoresis. Additionally, the H2O2 concentration after irradiation was determined. We observed that (1) the DNA damage per laser shot and (2) the enzyme-sensitive base lesions per total DNA damage decreased as the laser repetition rate increased. Furthermore, (3) extraordinarily short DNA fragments were likely to be produced, compared with those produced using X-rays, and (4) most OH radicals could be eliminated by recombination to generate H2O2, preventing them from damaging the DNA. The Monte-Carlo simulation of the strand break formation implies that the observed dependency of strand break efficiency on the laser repetition rate is mainly due to diffusion of DNA molecules. These findings quantitatively and qualitatively revealed that an intense laser pulse induces a specific DNA damage profile that is not induced by X-rays, a sparsely ionizing radiation source.

The spin-orbit charge transfer intersystem crossing (SOCT-ISC) photophysical process has shown great potential for constructing heavy-atom-free photosensitizers (PSs) for photodynamic therapy (PDT) of tumors. However, for almost all such PSs reported to date, the SOCT-ISC is driven by the acceptor-excited photoinduced electron transfer (a-PeT). In this work, for the first time the donor-excited photoinduced electron transfer (d-PeT)-driven SOCT-ISC mechanism is utilized to construct the heavy-atom-free PSs for PDT of tumors by directly installing the electron-deficient N-alkylquinolinium unit (as an electron acceptor) into the meso-position of the near-infrared (NIR) distyryl Bodipy chromophore (as an electron donor). In the less polar environment, the PSs exist as the monomer and promote the production of singlet oxygen (1O2) (Type-II) relying on the d-PeT-driven population of the triplet excited state via SOCT-ISC, whereas in the aqueous environment, they exist as nanoaggregates and induce the generation of superoxides (O2-•) and hydroxyl radicals (HO•) (Type-I) via the d-PeT-driven formation of the delocalized charge-separated state. The PSs could rapidly be internalized into cancer cells and induce the simultaneous production of intracellular 1O2, O2-•, and HO• upon NIR light irradiation, endowing the PSs with superb photocytotoxicity with IC50 values up to submicromolar levels whether under normoxia or under hypoxia. Based on the PSs platform, a tumor-targetable PS is developed, and its abilities in killing cancer cells and in ablating tumors without damage to normal cells/tissues under NIR light irradiation are verified in vitro and in vivo. The study expands the design scope of PSs by introducing the d-PeT conception, thus being highly valuable for achieving novel PSs in the realm of tumor PDT.

To investigate the effect of CPPU (forchlorfenuron) on optical properties of strawberry during growth, the optical properties (absorption coefficient (μa) and reduced scattering coefficient (μs\')) of strawberry treated with CPPU solutions at different concentrations (0, 2.5, 5.0 and 7.5 mg/L) were measured in white, color turning and red stages by using a single integrating sphere system over near-infrared wavelength range of 900-1700 nm. The physicochemical properties, i.e., single fruit weight, soluble solids content, firmness and moisture content, as well as microstructure of strawberry were also investigated. The results showed that in white stage, the μa of strawberry treated with 7.5 mg/L CPPU was significantly (p ≤ 0.05) lower than that of untreated strawberry at absorption peak of 1411 nm. In color turning stage, the μs\' of strawberry treated with 5 mg/L CPPU was significantly lower than that of treated with 2.5 mg/L at absorption peaks of 975, 1197 and 1411 nm. In red stage, the μa of strawberry treated with 2.5 mg/L CPPU was significantly (p ≤ 0.05) different from that of treated with 7.5 mg/L at 1197 nm. The study indicates that the optical properties of strawberry were affected by CPPU, and it provides useful information for identifying CPPU treated strawberry.

Zn2+ plays a vital role in regulating various life processes, such as gene expression, cell signaling, and brain function. In this study, a near-infrared fluorescent probe AXS was synthesized to detect Zn2+ with good fluorescence specificity, high selectivity, and high sensitivity; the detection limit of Zn2+ was 6.924 × 10-11 M. The mechanism of Zn2+ recognition by the AXS probe was investigated by 1H nuclear magnetic resonance titrations, UV-visible spectroscopy, fluorescence spectroscopy, Fourier-transform infrared spectroscopy, and high-resolution mass spectrometry. Test paper experiments showed that the AXS probe could detect Zn2+ in real samples. In addition, quantitative and qualitative detection of Zn2+ in common foodstuffs was achieved. For portable Zn2+ detection, a smartphone detection platform was also developed based on the AXS probe. Importantly, the AXS probe showed good bioimaging capabilities in Caenorhabditis elegans and mice.

[This corrects the article DOI: 10.3389/fimmu.2022.1028733.].