【JACS】北京师范大学毛兰群🔷利用MOF载体近红外调控内源信号，实现单细胞级神经精准调制新突破，尖峰频率激增70%#

Scheme 1. Schematic Illustration of NIR-Triggered NO Release for Neuromodulation in Deep Brain#

Figure 1. Synthesis and Characterizations of UCNP@MOF-NO Nanocomposites. (a) Schematic illustration of the fabrication process for core–shell UCNP@MOF-NO nanocomposites. (b) Postmodification process of the UiO-66-NH2 MOF shell. (c, d) TEM images of UCNP (c) and UCNP@MOF-NO (d). Inset in (d) shows a magnified single core–shell structure with lattice fringes of 2.07 nm. (e) HAADF-STEM image and corresponding elemental mapping images of UCNP@MOF-NO. Blue, Zr; Red, O; Slate blue, N; Pink, Na; Orchid, Gd; Orange, Yb; Deep pink, Tm; Yellow, F. (f) XRD patterns of UiO-66-NH2, MOF-NO, UCNP, UCNP@MOF, and UCNP@MOF-NO. (g) FTIR spectra of UCNP, MOF-NO, and UCNP@MOF-NO. (h) DLS profiles of UCNP and UCNP@MOF-NO. Data are presented as mean ± SD (n = 3).#

紧接着，团队对其光控释放动力学进行了深度表征。如图2所示，在980纳米近红外光的激发下，核心吸收光子并转化为紫外光，直接辐射激发外壳的MOF-NO发生光解反应，展现出极佳的“开-关”瞬时响应性。释放的一氧化氮浓度与近红外光照时间、功率密度及材料浓度均呈现出完美的线性关系，实现了化学剂量的精准可调。

Figure 2. NIR-triggered NO release capacity of UCNP@MOF-NO. (a) Schematic illustration of NIR light-triggered NO release mechanism via bond cleavage. (b) Fluorescence emission spectrum of UCNP (λex = 980 nm) and UV–vis absorption spectrum of MOF-NO in aCSF. (c) Time-resolved photoluminescence decay profiles of UCNP and UCNP@MOF-NO monitored at 478 nm under pulsed 980 nm excitation. (d) Cumulative NO release concentration from UCNP@MOF-NO (200 μg mL–1) during five consecutive on–off NIR irradiation cycles (980 nm, 2 min on/2 min off) at different power densities. (e) Linear correlation between NO release concentration and irradiation time at different power densities (_R_2 > 0.999 for all fitted curves). (f) Linear correlation between NO release concentration and NIR power density at different irradiation durations (_R_2 > 0.99 for all fitted curves). (g) Linear correlation between NO release concentration and UCNP@MOF-NO concentration (_R_2 = 0.996) following 4 min NIR irradiation (1.5 W cm–2). (h) NO release capacity of UCNP@MOF-NO (100 μg mL–1) upon NIR irradiation (1.5 W cm–2, 15 min) stored in aCSF at room temperature for different periods of time. All data are presented as mean ± SD (n = 5).#

随后，团队在细胞水平验证了这一平台的神经调制功效。如图3所示，利用单细胞安培法实时捕捉PC12细胞的囊泡神经递质释放，发现在近红外光精准照射仅5秒后，便能强烈诱导儿茶酚胺分子的胞吐释放。这一过程深入解析为双重协同机制：外源释放的NO一方面触发了细胞膜上TRP通道的S-亚硝基化反应，打开通道孔道引起持续的细胞外钙离子内流；另一方面，NO跨膜进入细胞内部激活可溶性鸟苷酸环化酶（sGC），引起胞内cGMP第二信使水平的显著升高。此外，红外热成像仪证实该过程没有 photothermal 热效应干扰，纯属化学调制。

Figure 3. In vitro neuromodulation via the UCNP@MOF-NO platform. (a) Cell viability of PC12 cells incubated with different concentrations of UCNP@MOF-NO for 24 h followed with NIR irradiation (1.5 W cm–2, 5 s). Data are presented as mean ± SD (n = 5). (b) Optical micrograph showing a CFE positioned on a PC12 cell surface for single-cell amperometric analysis. (c) Representative amperometric current traces of exocytotic vesicle release from PC12 cells under different treatments as indicated. (d) Schematic diagram of possible protein conformation changes during activation of TRP channels by NO. (e, f) Time-dependent confocal fluorescence microscopy images (e) and quantified average fluorescence intensity (f) of intracellular Ca2+ in PC12 cells treated with various materials (200 μg mL–1) upon NIR irradiation (1.5 W cm–2, 5 s). Data are presented as mean ± SEM (n = 32 for UCNP@MOF-NO; n = 36 for UCNP@MOF). (g) Schematic diagram of NO-induced activation of the intracellular sGC-cGMP signaling pathway. (h) Quantification of intracellular cGMP levels in 5 × 104 PC12 cells following stimulation with UCNP@MOF or UCNP@MOF-NO (200 μg mL–1) under NIR irradiation (1.5 W cm–2, 5 s). Data are presented as mean ± SD (n = 6, each group). Statistical significance was assessed using an unpaired t test with Welch’s correction.#

Figure 4. In vivo monitoring of NIR-triggered NO release from UCNP@MOF-NO. (a) Spatial diffusion profile of NIR-triggered NO release from UCNP@MOF-NO. The pseudocolor map illustrates the concentration gradient of NO. (b) Temporal evolution of NIR-triggered NO concentration at a lateral distance of 0.1 mm from the UCNP@MOF-NO injection site. (c) Structure of the NO microsensor. (d) SEM image of a carbon fiber modified with Ni–N4 SAC. (e) TEM image of Ni–N4 SAC. (f) Cyclic voltammograms of Ni–N4 SAC-modified CFE in N2-saturated aCSF with (orange line) and without (green line) 0.18 mM NO. (g) Amperometric responses recorded in the mouse hippocampal CA1 region before and after NIR irradiation (1.5 W cm–2, 5 s), showing the results for UCNP@MOF-NO at +0.8 V (orange line), UCNP@MOF-NO at +0.5 V (green line), and UCNP@MOF at +0.8 V (purple line).#

最后，研究团队将该技术应用于活体小鼠研究。如图4所示，在将纳米晶立体定位注射至小鼠大脑海马体CA1区后，利用Ni-N4单原子催化剂修饰的微传感器成功在活体内原位监测到了微摩尔级别的NO瞬态动力学过程。在此基础上，通过微电极阵列进行了活体电生理记录。如图5所示，在仅仅5秒的近红外光照射下，目标区域神经元的自发放电频率瞬间飙升了约70%，且波形未发生改变，证明其高度符合生理特性。组织免疫荧光检测进一步证实，材料注射15天后未引发明显的星形胶质或小胶质细胞炎症反应，且无细胞凋亡，展现了卓越的活体生物相容性。

Figure 5. In vivo modulation effect of UCNP@MOF-NO on neural activity. (a) Schematic diagram of in vivo electrophysiological recording. (b) Representative action potential traces recorded before and after NIR irradiation in mice with UCNP@MOF or UCNP@MOF-NO. (c) Corresponding waveforms of representative action potentials recorded from the two treatment groups. (d) Typical time-frequency diagrams showing firing frequency changes over time in neurons from the hippocampal CA1 region treated with UCNP@MOF-NO (orange line) or UCNP@MOF (green line). (e) Statistical comparison of spike counts before (0–60 s) and after (65–125 s) NIR irradiation (1.5 W cm–2, 5 s) in UCNP@MOF-NO- and UCNP@MOF-treated groups. Data are presented as mean ± SD from n = 13 valid channels across 5 mice (UCNP@MOF-NO) and n = 12 valid channels across 5 mice (UCNP@MOF). Statistical significance was determined using a paired two-tailed t test. (f) Immunofluorescence analysis of hippocampal CA1 tissue 15 days postinjection of aCSF or UCNP@MOF-NO, showing glial responses indicated by GFAP (green) for astrocyte activation and Iba-1 (red) for microglial activation. Dashed boxes denote the injection sites. (g) Apoptosis assessment in hippocampal tissue 7 days postinjection of aCSF or UCNP@MOF-NO, showing DAPI-stained nuclei (blue) and TUNEL staining (green) for detection of apoptotic cells.#