Preparation of Pig Bone Nitrogen-doped Carbon Quantum Dots and Application in Detection of Co²⁺ Enhanced Publication

猪骨氮掺杂碳量子点制备及其用于检测Co 2+ Preparation of Pig Bone Nitrogen-doped Carbon Quantum Dots and Application in Detection of Co 2+ 1 first-author 钱玟(1997-)，男，四川巴中人，硕士研究生，2019年于四川农业大学获得学士学位，主要从事食品检测荧光探针技术的研究。E-mail: 1980385367@qq.com http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123845&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123848&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123851&type= 钱玟 (1997-)，男，四川巴中人，硕士研究生，2019年于四川农业大学获得学士学位，主要从事食品检测荧光探针技术的研究。E-mail: 1980385367@qq.com 1980385367@qq.com 1 corresp E-mail: helifood@163.com E-mail: helifood@163.com 何利(1984-)，女，重庆人，博士，副教授，硕士研究生导师，2011年于四川大学获得博士学位，主要从事食品资源综合利用、食品安全检测技术的研究。E-mail: helifood@163.com http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123854&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123855&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123860&type= 何利 (1984-)，女，重庆人，博士，副教授，硕士研究生导师，2011年于四川大学获得博士学位，主要从事食品资源综合利用、食品安全检测技术的研究。E-mail: helifood@163.com helifood@163.com 1 1 1 1 1 1 四川农业大学　食品学院，四川　雅安　625014 四川农业大学　食品学院，四川　雅安　625014 College of Food Science, Sichuan Agricultural University, Yaan 625014, China College of Food Science, Sichuan Agricultural University, Yaan 625014, China 以猪骨和乙二胺为碳源和氮源，通过一步水热法合成了氮掺杂碳量子点(N-CQDs)，并优化其制备条件。通过透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、X射线衍射图(XRD)、紫外-可见吸收光谱(UV-Vis)和X射线光电子能谱(XPS)技术，研究了N-CQDs的结构和光学性质及元素组成。所制备的N-CQDs具有较高的量子产率(26.4%)，平均粒径为2.34 nm，在365 nm紫外光照射下呈现出明亮的蓝色荧光。研究发现Co 2+ 对N-CQDs有良好的猝灭作用，从而建立了一种快速检测Co 2+ 的新方法。N-CQDs荧光猝灭强度与Co 2+ 浓度在0~15 μg/mL和30~80 μg/mL呈良好的线性关系，检出限为20 μg/L，加标回收率为97.26%~109.14%,RSD < 3.24%，能够应用于实际水样中Co 2+ 含量的测定。 Nitrogen-doped carbon quantum dots(N-CQDs) were successfully synthesized using pig bone and ethylenediamine as carbon and nitrogen sources by one-step hydrothermal method. Structure, optical properties and element composition of N-CQDs have been studied by transmission electron microscope(TEM), Fourier transform infrared spectroscopy(FT-IR), X-ray diffractometer patterns(XRD), UV-Vis absorption spectroscopy(UV-Vis) and X-ray photoelectron spectroscopy(XPS) technologies. The synthesized N-CQDs have a high quantum yield(26.4%), an average particle size of 2.34 nm, showing bright blue fluorescence under a 365 nm UV lamp. The study found that Co 2+ had a good quenching effect on N-CQDs, so as to establish a new method for rapid detection of Co 2+ . The fluorescence quenching intensity of N-CQDs has a good linear relationship with the concentration of Co 2+ at 0-15 μg/mL and 30-80 μg/mL, the detection limit is 20 μg/L, and the recovery rate of standard addition is 97.26%-109.14%, RSD < 3.24%, which can be applied to the determination of Co 2+ content in actual water samples. 氮掺杂碳量子点 猪骨 荧光检测 Co 2+ nitrogen-doped carbon quantum dots pig bone fluorescence detection Co 2+ 1　引言 1 碳量子点(Carbon quantum dots,CQDs)是一类尺寸小于10 nm具有量子限域效应的新型零维碳纳米材料 [ 1 1 ] ，与金属纳米团簇和传统的半导体量子点相比，CQDs由于其低毒性 [ 2 2 ] 、更宽的光致发光光谱 [ 3 3 ] 和高荧光稳定性 [ 4 4 ] 等独特优势，可被开发为具有快速、选择性好、灵敏度高和低毒性等出色性能的荧光探针，用于选择性检测有害物质。 钴离子(Co 2+ )是人体必需的一种微量元素，可以促使红细胞和部分酶的合成、调节酶和辅助因子的催化活性，在人体中起着重要作用 [ 5 5 - 6 6 5-6 ] 。但是，过量摄入Co 2+ 会使机体内的自由基过剩，导致细胞凋亡，进而使人患上哮喘、鼻炎、过敏性皮炎和心肌病等疾病 [ 7 7 ] 。考虑到Co 2+ 引起的毒性作用，世界卫生组织(WHO)规定饮用水中Co 2+ 的限量为40 μg/L [ 8 8 ] 。现有的CQDs检测Co 2+ 方法大多以化学物质为前体，对环境及人体健康造成一定的危害，且量子产率较低。田等 [ 9 9 ] 以化学物质对苯二胺和天冬酰胺为原料，通过一步水热法合成了绿色荧光的N-CQDs，用于检测Co 2+ 及生物成像，但量子产率仅为15.5%。京等 [ 10 10 ] 以丙烯酸碳源，乙二胺为氮源，采用水热法制备了N-CQDs，量子产率为22.7%。因此，以生物质材料为碳源，采用简单、快速、可控的水热法合成高荧光CQDs，成为了分析检测研究的热点。 我国是世界上禽、畜产量最多的国家之一，2018年中国猪肉总产量为5 400万吨，约占全球产量的50%，若以猪骨占猪肉的9%~14%计算 [ 11 11 ] ，我国年均产生486~756万吨猪骨。然而，除排骨和腔骨可直接用于饮食而被大量需求外，其他骨头的利用率均不高，造成了极大的资源浪费和环境危害。由于猪骨富含脂肪与蛋白质等物质，可作为制备碳量子点的良好碳源，因此本文以生物质废弃物猪骨(棒子骨)、乙二胺为前驱体，采用绿色经济的水热法合成猪骨氮掺杂碳量子点(N-CQDs)，通过各种表征技术研究了N-CQDs的结构和光学性质，探究了N-CQDs的稳定性，建立了一种快速检测Co 2+ 的碳量子点荧光分析方法，并用于实际样品中Co 2+ 的检测。 2　实验 1 2.1　实验试剂与仪器 2 试剂:猪骨(棒子骨)收集于中国雅安苍坪山农贸市场(将猪骨剔除碎肉洗净后，置于60 ℃烘箱中烘干，然后用粉碎机研磨成粉末状，100目过筛保存备用)。乙二胺、CoCl 2 、KCl、ZnCl 2 、BaCl 2 、MgCl 2 、NaCl、CdCl 2 、CaCl 2 、NiCl 2 、FeCl 3 、CuCl 2 、HgCl 2 、AlCl 3 、MnCl 2 、CrCl 3 、硝酸溶液均购于成都市科隆化学品有限公司(中国成都)。硫酸奎宁购自迈坤化工有限公司(中国上海)。其他化学药品和溶剂均购自万科试剂有限公司(中国雅安)，所有试剂均为分析纯。 仪器:Varioskan Flash全波长扫描式酶标仪(美国赛默飞世尔科技有限公司);Lumina荧光分光光度计(美国赛默飞世尔科技有限公司);NICOLETiS10 型傅里叶变换红外光谱仪(美国赛默飞世尔科技有限公司);TEM-2100透射电子显微镜(日本LJEMOC);Milli-Q Gradient超纯水系统(美国密理博公司);Shimadzu D/Max-2500 X射线衍射仪(日本岛津公司)等。 2.2　N-CQDs制备 2 本实验采用水热法制备绿色生物质猪骨氮掺杂碳量子点。制备方法如下:将骨粉与乙二胺混合在60 mL去离子水中搅拌均匀，然后将混合物转移到100 mL四氟乙烯内胆 Teflon反应釜中，并在烘箱中恒温加热，待反应液冷却得到黄褐色溶液。离心(4 000 r/20 min)后用0.22 μm滤膜过滤除去大颗粒杂质得到N-CQDs溶液，在4 ℃冰箱中避光保存。考察反应温度(160,180,200,220,240 ℃)、反应时间(8,10,12,14,16 h)、骨粉量(4,5,6,7,8 g)和乙二胺量(0.6,0.7,0.8,0.9,1 mL)对N-CQDs荧光强度的影响，确定最佳制备条件。 2.3　N-CQDs表征 2 TEM-2100透射电子显微镜进行形貌特征分析；Lumina荧光分光光度计测量N-CQDs的荧光光谱；NICOLETiS10 型傅里叶变换红外光谱仪测定N-CQDs表面官能团；XRD-6000X射线衍射光谱仪测定XRD 谱图；Shimadzu D/Max-2500 X射线衍射仪测定XPS谱图；MAZ2012马尔文粒度仪测定Zeta电位。 2.4　量子产率(QY)测定 2 使用硫酸奎宁(在350 nm的0.1 mol/L H 2 SO 4 中 QY=54%)为参比物质，分别测试N-CQDs和硫酸奎宁的紫外-可见吸收光谱及荧光光谱，代入公式(1): http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123862&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123865&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123867&type= 其中 η 为量子产率， I 表示荧光发射强度， n 表示溶剂的折射率， A 表示吸光度。下标R和S分别表示已知的荧光标准样品和实验样品 [ 10 10 ] 。 2.5　N-CQDs稳定性测定 2 将制备得到的N-CQDs溶液每隔7 d记录荧光发射光谱，考察N-CQDs储藏时间稳定性。将N-CQDs溶液置于365 nm紫外光下，分别照射0,30,60,90,120,150,180 min，考察N-CQDs光漂白稳定性。用0.5 mol/L的盐酸和氢氧化钠溶液调节N-CQDs溶液的pH值，考察N-CQDs的pH稳定性。在N-CQDs溶液中加入50 μL NaCl溶液，其浓度分别为0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1 mol/L，考察N-CQDs的离子稳定性。上述所有测试均是在417 nm激发波长下记录荧光发射光谱，平行测定3次。 2.6　N-CQDs检测Co 2+ 2 在荧光比色皿中，加入1 mL 100倍分散体 N-CQDs 溶液、1 mL PBS(pH=7)以及分别加入浓度为 0.1,0.5,1,2,5,8,10,12,15, 20,25,30,40,50,60,70,80,90,100 μg/mL 的Co 2+ 溶液，混合均匀后20 ℃反应10 min。417 nm激发波长下记录荧光发射光谱，以荧光猝灭率 F/F 0 为指标( F 是加入Co 2+ 溶液时的荧光强度， F 0 是不加入Co 2+ 溶液时的荧光强度)。 在N-CQDs溶液中，分别加入1 mL浓度为100 μg/mL的金属离子水溶液(Co 2+ 、K + 、Zn 2+ 、Ba 2+ 、Mg 2+ 、Na + 、Cd 2+ 、Ca 2+ 、Ni 2+ 、Fe 3+ 、Cu 2+ 、Hg 2+ 、Al 3+ 、Mn 2+ 、Cr 3+ )，检测存在不同代表性离子的荧光强度，考察其选择性。 在N-CQDs溶液中，加入1 mL浓度为100 μg/mL的Co 2+ 溶液后，再分别加入不同倍数潜在干扰物离子溶液(Co 2+ 、K + 、Zn 2+ 、Ba 2+ 、Mg 2+ 、Na + 、Cd 2+ 、Ca 2+ 、Ni 2+ 、Fe 3+ 、Cu 2+ 、Hg 2+ 、Al 3+ 、Mn 2+ 、Cr 3+ 、H 2 P http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123870&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123877&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123874&type= 、N http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123880&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123886&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123882&type= 、C http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123888&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123895&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123893&type= 、S http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123897&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123904&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123901&type= 、OH - 、Lys、Asp、Cys、Trp、Thr、Gly、Phe)与体系混合，检测存在潜在干扰性离子条件下，体系的荧光强度变化，考察其抗干扰性。上述所有测试均是平行测定3次。 2.7　实际样品测定 2 分别以来自实验室的自来水和青衣江(中国雅安)的河水作为实际检测样品，评估N-CQDs检测Co 2+ 的实际适用性。根据HJ/T 91-2002采集样品后，将两种样品都分为两份。一份经0.45 μm微孔滤膜过滤，用硫酸溶液调节水样pH小于2，用于分光光度法检测(HJ 550-2015)；另一份经0.22 μm微孔滤膜过滤，用硫酸溶液调节水样pH至中性，用于N-CQDs检测。 3　结果与讨论 1 3.1　N-CQDs制备条件优化 2 为了获得高荧光性能的N-CQDs，考察了水热反应温度、水热反应时间、骨粉量和乙二胺量对N-CQDs荧光强度的影响。由 图2(a) 图2(a) 可知，水热反应温度为200 ℃时(6 g骨粉，0.8 mL乙二胺，12 h),N-CQDs荧光强度最高。当水热反应温度开始升高，N-CQDs荧光强度也随之增加，可能是由于在碳化过程中合成了更多的N-CQDs颗粒；但随着温度进一步升高，N-CQDs荧光强度下降，这可能是由于N-CQDs颗粒发生了团聚 [ 12 12 ] 。由 图2(b) 图2(b) 可知，当水热反应时间为12 h时(6 g骨粉，0.8 mL乙二胺，200 ℃),N-CQDs荧光强度达到最高值。由 图2(c) 图2(c) 可知，在骨粉量为6 g时(0.8 mL乙二胺，水热12 h,200 ℃)N-CQDs荧光最强。由2(d)可知，在乙二胺量为0.8 mL时(6 g骨粉，0.8 mL乙二胺，12 h),N-CQDs荧光强度最高，随着乙二胺用量继续增加，N-CQDs荧光强度降低，可能是由于表面氨基数量增加，更易导致碳量子点聚合，产生自猝灭 [ 13 13 ] 。 3.2　N-CQDs表征 2 图3(a) 图3(a) 显示，所制备的N-CQDs呈圆球形，分散性好，且尺寸均一，插图表明，N-CQDs晶格条纹的晶面间距为0.21 nm，与石墨碳相符 [ 14 14 ] 。 图3(b) 图3(b) 是N-CQDs的粒径分布图，可以得到N-CQDs的平均粒径大小为2.34 nm。 图3(c) 图3(c) 是N-CQDs的XRD谱图，N-CQDs在2 θ =22.2°出现宽峰，对应于石墨碳的(002)晶面，证实了N-CQDs的无定形结构 [ 15 15 - 16 16 15-16 ] 。为了了解N-CQDs的表面官能团，对掺杂与不掺杂碳量子点(CQDs)进行了傅里叶变换红外光谱分析，如 图3(d) 图3(d) 所示。3 440 cm -1 处的峰归属于O—H和N—H的伸缩振动 [ 17 17 ] ,2 962 cm -1 处的峰是由于C—H的伸缩振动 [ 18 18 ] ,1 655 cm -1 和1 510 cm -1 处的峰是C http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123922&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123925&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123923&type= O和C http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123927&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123932&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123930&type= C基团不对称拉伸振动的结果 [ 19 19 ] ,1 460 cm -1 处的峰归因于C—N的拉伸振动 [ 20 20 ] ,1 041 cm -1 处的峰归因于C—O的伸缩振动 [ 21 21 ] 。CQDs的FT-IR谱图不含C—N的拉伸振动吸收峰，说明氮原子成功掺杂，并且N-CQDs表面含有氨基、羧基等官能团。N-CQDs水溶液的Zeta电位值为-31.3 mV,N-CQDs粒子带负电，并具有一定的稳定性。 N-CQDs的光学性质通过紫外-可见吸收光谱和荧光光谱进行分析。 图4(a) 图4(a) 显示，N-CQDs在紫外吸收区表现出强烈的吸收，紫外吸收光谱在272 nm和332 nm处存在两个特征峰，在272 nm处的峰归因于C http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123937&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123939&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123938&type= C的π-π * 轨道跃迁 [ 22 22 ] ,332 nm处的峰归因于C http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123940&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123942&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123941&type= O的n-π * 轨道跃迁 [ 23 23 ] 。荧光光谱表明，N-CQDs的最大发射峰位于488 nm，最大激发波长为417 nm。 图4(a) 图4(a) 插图显示，N-CQDs的水溶液在日光下呈黄褐色，在365 nm紫外光下呈蓝色。 图4(b) 图4(b) 显示，在340~460 nm的激发波长以20 nm的增量得到的N-CQDs发射光谱，随着激发波长的增加，最大发射峰发生红移，表明N-CQDs具有激发波长依赖性，这种现象可能与N-CQD表面不均匀的化学结构、分子状态及量子限域效应有关 [ 24 24 - 25 25 24-25 ] 。以硫酸奎宁(0.1 mol/L H 2 SO 4 ,QY=54%)为标准物质，测得的N-CQDs的量子产率为26.4%。 采用XPS分析了N-CQDs表面的化学元素及化学键，如 图5(a) 图5(a) 所示，3个吸收峰分别对应C1s、N1s、O1s，键能分别为285.08,400.08,532.08 eV,3种元素的含量分别为64.41%、8.6%、26.98%。对XPS全谱图进行分峰，结果如 图5(b)~(d) 图5(b)~(d) 。 图5(b) 图5(b) 是C1s的分峰图，对应的键能分别为284.69,285.69,288.03 eV，分别对应C—C、C—N、C http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123947&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123951&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123949&type= O/C http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123953&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123955&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123954&type= N [ 26 26 ] 。 图5(c) 图5(c) 是N1s的分峰图，对应的键能分别为399.05,399.9,401.16 eV，分别对应O http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123956&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123958&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123957&type= C—N、C—N—C、N—H [ 27 27 - 28 28 27-28 ] 。 图5(d) 图5(d) 是O1s的分峰图，对应的键能分别为531.1,532.08,532.64 eV，分别对应C http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123960&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123964&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123962&type= O、C—O、C—OH/C—O—C [ 29 29 - 30 30 29-30 ] 。这些结果与FT-IR结果一致，表明N-CQDs表面具有含氧和含氮基团，赋予了N-CQDs良好的水溶性。由 图6 图6 可知，N-CQDs在4 ℃条件下保存60 d后荧光强度下降，可能是由于N-CQDs间产生团聚，造成荧光强度减弱。在紫外照射180 min、不同浓度NaCl条件和较宽的pH范围内，N-CQDs依然显示出强荧光、良好的稳定性和抗漂白性。 3.3　N-CQDs检测Co 2+ 2 如 图7(a) 图7(a) 所示，研究了N-CQDs对不同金属离子的选择性，将各种金属离子分别添加到N-CQDs的水溶液中，包括Co 2+ 、K + 、Zn 2+ 、Ba 2+ 、Mg 2+ 、Na + 、Cd 2+ 、Ca 2+ 、Ni 2+ 、Fe 3+ 、Cu 2+ 、Hg 2+ 、Al 3+ 、Mn 2+ 、Cr 3+ ，金属离子的浓度均为100 μg/mL，仅Co 2+ 具有猝灭N-CQDs荧光强度的能力，而其他金属离子几乎没有猝灭作用。 图7(b) 图7(b) 显示，在N-CQDs/Co 2+ 溶液中加入其他干扰物质后，溶液的荧光强度无明显变化，表明这些干扰物质对Co 2+ 的测定基本无干扰，这可能是由于Co 2+ 与N-CQDs表面的某些官能团(—COOH、—OH、—CONH)反应形成复合物，促使电子从N-CQDs的激发态转移到Co 2+ 的3d轨道，导致荧光猝灭 [ 38 38 ] 。如 图7(c)、(d) 图7(c)、(d) 所示，随着Co 2+ 浓度的增加，N-CQDs在488 nm处的荧光强度逐渐降低。Co 2+ 浓度为0~15 μg/mL( Y =-0.01104 X +0.98879, R 2 =0.980 21)和30~80 μg/mL( Y =-0.0034 X +0.85301, R 2 =0.990 06)时与N-CQDs猝灭程度呈线性关系，检出限( S/N =3)达到20 μg/L，低于WHO规定的限量值。与 表1 表1 中Co 2+ 检测方法相比较，本方法具有检出限较低、线性范围宽、成本低等优点。 1 1 　方法 1 1 材料 1 1 线性范围 1 1 检出限 1 1 参考文献 1 1 荧光 1 1 N-CQDs 1 1 0~15 μg·mL -1 , 30~80 μg·mL -1 1 1 20 μg·L -1 (0.34 μmol·L -1 ) 1 1 本方法 1 1 比色分析 1 1 硫化锌量子点 1 1 10~1 000 mg·L -1 1 1 10 mg·L -1 1 1 [ 31 31 ] 1 1 荧光 1 1 N-CQDs 1 1 0~90 μmol·L -1 1 1 0.4 μmol·L -1 1 1 [ 32 32 ] 1 1 荧光 1 1 CQDs 1 1 0.1~30 μmol·L -1 1 1 0.052 μmol·L -1 1 1 [ 33 33 ] 1 1 荧光 1 1 N-CQDs 1 1 5~30 μmol·L -1 1 1 0.43 μmol·L -1 1 1 [ 34 34 ] 1 1 荧光 1 1 CQDs 1 1 0~40 μmol·L -1 1 1 0.45 μmol·L -1 1 1 [ 35 35 ] 1 1 吸光度 1 1 金纳米粒子 1 1 1 000~15 000 μmol·L -1 1 1 14 μmol·L -1 1 1 [ 36 36 ] 1 1 荧光 1 1 N,S-CQDs 1 1 0.08~100 μmol·L -1 1 1 0.08 μmol·L -1 1 1 [ 37 37 ] 荧光猝灭是荧光分子的表面基团与猝灭物质发生反应，导致荧光强度降低，通常分为静态猝灭和动态猝灭。静态猝灭的荧光猝灭常数随温度升高而减小，动态猝灭的荧光猝灭常数随温度升高而增大 [ 29 29 ] 。为了研究Co 2+ 对N-CQDs荧光猝灭的机理，本文考察了不同温度下Co 2+ 对N-CQDs的猝灭作用，并用Stern-Volmer方程来判断猝灭机理。Stern-Volmer方程为: http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123977&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123978&type= http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=22123979&type= 其中 F 0 是不加入Co 2+ 溶液时N-CQDs的荧光强度， F 是加入Co 2+ 溶液时N-CQDs的荧光强度， K SV 是Stern-Volmer猝灭常数， C 为加入Co 2+ 的浓度，曲线如 图7(e) 图7(e) 所示。在15,25,35 ℃下，猝灭常数 K SV 分别为0.013 1,0.011 9,0.009，即随着温度升高，猝灭常数 K SV 减小，表明Co 2+ 是通过静态猝灭使得N-CQDs的荧光发生猝灭。此外， 图7(f) 图7(f) 显示，在N-CQDs溶液中加入Co 2+ 后，其紫外吸收峰发生了变化，这可能是Co 2+ 与N-CQDs的表面官能团形成了非荧光的基态复合物，并没有在N-CQDs的激发态发生反应。以上结果充分证明Co 2+ 对N-CQDs的荧光猝灭类型为静态猝灭。 3.4　实际样品中Co 2+ 的检测 2 选择自来水和河水为实际样品，然后采用加标回收法检测水样中的Co 2+ ，结果如 表2 表2 所示。该方法的回收率为97.26%~109.14%,RSD < 3.24%，回收率的准确度优于分光光度法分析结果96.15%~117.05%，表明N-CQDs能够用于实际水样中Co 2+ 的检测。 1 2 Sample 1 2 Found/(μg·L -1 ) 1 2 Added/ (μg·L -1 ) 3 1 N-CQDs 3 1 HJ 550-2015 1 1 Total found/(μg·L -1 ) 1 1 Recover/% 1 1 RSD/% 1 1 Total found/(μg·L -1 ) 1 1 Recover/% 1 1 RSD/% 1 3 River water 1 1 0 1 1 20 1 1 21.83 1 1 109.14 1 1 1.63 1 1 23.41 1 1 117.05 1 1 2.32 1 1 0 1 1 40 1 1 39.25 1 1 98.13 1 1 3.24 1 1 44.70 1 1 111.75 1 1 5.71 1 1 0 1 1 80 1 1 77.81 1 1 97.26 1 1 3.19 1 1 78.24 1 1 97.80 1 1 4.36 1 3 Tap water 1 1 0 1 1 20 1 1 19.57 1 1 97.85 1 1 1.91 1 1 19.23 1 1 96.15 1 1 4.60 1 1 0 1 1 40 1 1 41.14 1 1 102.85 1 1 0.90 1 1 44.15 1 1 110.38 1 1 4.05 1 1 0 1 1 80 1 1 79.26 1 1 99.08 1 1 1.25 1 1 84.17 1 1 105.21 1 1 2.83 4　结论 1 本文以生物质废弃物猪骨为碳源，通过一步水热法合成了N-CQDs。XPS和FT-IR表征分析表明氮元素成功掺杂到碳量子点的结构中。N-CQDs的平均粒径为2.34 nm，颗粒分散均匀，表现出良好的溶解度、高稳定性和高荧光强度。基于Co 2+ 能够有效猝灭N-CQDs的荧光，建立了一种高灵敏性和选择性的Co 2+ 的检测方法，检测线性范围为0~15 μg/mL和30~80 μg/mL，检出限为20 μg/L，并能够用于实际样品中Co 2+ 的检测，为环境分析提供了一种简单、快速、灵敏的检测Co 2+ 的新方法。 本文专家审稿意见及作者回复内容的下载地址:http://cjl.lightpublishing.cn/thesisDetails#10.37188/CJL.20210260. 参考文献: TRUFFAULT L , TA M T , DEVERS T , et al . 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