超顺磁氧化铁纳米微粒在HER-2阳性乳腺癌模型MRI和荧光成像中的应用

目的分析超顺磁氧化铁纳米微粒(SPIONs)在人表皮生长因子受体2(HER-2)阳性乳腺癌模型磁共振成像(MRI)和荧光成像中的应用。方法建立纳米探针,对其表征进行检测。制备乳腺癌小鼠模型,采用纳米探针于小鼠尾静脉注射,采用荧光成像和MRI判断纳米颗粒能否聚集于乳腺癌病灶部位。分别设置对照组、A组(应用四氧化三铁-免疫球蛋白G-吲哚菁绿)、B组(应用曲妥珠单抗+四氧化三铁-曲妥珠单抗-吲哚菁绿)、C组(应用四氧化三铁-曲妥珠单抗-吲哚菁绿)。检测纳米颗粒表征,给予小鼠活体MRI和活体荧光成像检查。结果本实验通过建立SPIONs,纳米颗粒平均粒径为(25. 89±3. 63) nm。偶联后的纳米颗粒于828处存在明显吸收峰,与荧光染料吲哚菁绿的荧光发射波长相同。纳米颗粒弛豫率较高,达107. 67 nM~(-1)·s~(-1)。纳米颗粒溶液在近红外激光持续照射后的温度最高达57. 85℃。采用纳米探针于小鼠尾静脉注射1 d后,活体MRI癌灶部位T_2信号最低。C组小鼠癌灶部位△T_2值为(30. 68±5. 14) ms,较对照组(3. 13±0. 98) ms、A组(4. 52±1. 15) ms、B组(12. 14±2. 25) ms显著升高(P 0. 05); B组小鼠癌灶部位△T_2值较对照组和A组显著升高(P 0. 05)。活体荧光成像可见纳米颗粒于小鼠癌灶组织和腹腔脏器出现一过性浓聚,且经膀胱进行排泄,1 d后于癌灶部位出现明显聚集。结论构建四氧化三铁-曲妥珠单抗-吲哚菁绿的SPIONs纳米探针可能是HER-2阳性乳腺癌MRI和荧光成像的一种潜在显像剂。     

Fe3O4(核)/Au(壳)纳米颗粒探针的制备及其在检测乙型肝炎病毒DNA中的应用

目的制备Fe3O4(核)/Au(壳)纳米颗粒乙型肝炎病毒脱氧核糖核酸(hepatitis B virus deoxynucleic acid,HBV DNA)基因探针,研究其在检测HBV DNA中的应用.方法分别用枸橼酸还原金氯酸法、化学共沉淀法制备Au、Fe3O4纳米颗粒,二法结合制备Fe3O4(核)/Au(壳)纳米颗粒.通过金-硫(Au-S)共价键,将烷氢硫醇修饰的寡核苷酸结合在Fe3O4(核)/Au(壳)纳米颗粒上,制备纳米颗粒HBV DNA基因探针.用荧光标记法检测纳米颗粒探针表面寡核苷酸的覆盖率和与其互补的寡核苷酸的杂交效率.在尼龙膜上,使用Fe3O4(核)/Au(壳)纳米颗粒基因探针通过斑点杂交法、Ag染色法检测HBV DNA.在纳米颗粒基因探针液相检测体系中加入HBV DNA,透射电镜下观察.结果制备的Fe3O4(核)/Au(壳)纳米颗粒粒径均匀,为(15±5)nm,水相分散良好,具有磁性.Fe3O4(核)/Au(壳)纳米颗粒基因探针表面寡核苷酸的最大覆盖率为(120±8)条,最大杂交效率为(14±2)%.斑点杂交法可检出低至1010copies/ml的合成靶DNA,可目视化检出乙肝患者血清中HBV DNA的PCR产物.在液相检测体系中加入HBV DNA,透射电镜观察到纳米颗粒组装成大的网状结构的聚集体.结论成功制备了Fe3O4(核)/Au(壳)纳米颗粒HBV DNA基因探针,它可直接用于HBV DNA的检测.     

钙掺杂调节四氧化三铁纳米酶活性及其抗病毒作用

目的探讨钙掺杂对四氧化三铁(Fe_3O_4)纳米酶活性的影响。方法通过水热合成反应将钙掺杂到Fe_3O_4纳米酶中,系统表征和分析钙掺杂对Fe_3O_4纳米酶形貌和催化活性的影响。结果尽管钙掺杂原子比例较低,但会导致纳米颗粒表面更加粗糙且带有正电荷,其中过氧化物酶活性降低,而过氧化氢酶活性增强。钙掺杂Fe_3O_4纳米酶具有抗流感病毒作用。结论钙掺杂不仅可以调节Fe_3O_4纳米酶的活性,还在抗病毒方面具有潜在的应用价值。     

磁性纳米颗粒Fe_3O_4@SiO_2的制备及在全血DNA提取中的应用

目的自制Fe_3O_4@SiO_2磁性纳米颗粒并评价在全血样本中DNA提取效果,进一步研究开发磁珠法检测HBV DNA的技术。方法采用溶剂热法自制Fe_3O_4磁性纳米颗粒,并用表面化学修饰法制备Fe3O4@SiO_2磁性复合颗粒;利用该颗粒经吸附、洗涤、洗脱等步骤提取全血样本中DNA,并通过电泳、PCR扩增等传统技术检测DNA提取效果,与煮沸法提取血清DNA样本的效果进行对比。结果成功制备出直径约550 nm的Fe_3O_4@SiO_2磁性纳米颗粒,该颗粒分散均匀;自制的磁性纳米颗粒可用于全血DNA提取与纯化,实验操作简便。自制磁性纳米颗粒提取全血DNA浓度为150.56 ng/μL,纯度为1.53;该提取方法与传统煮沸裂解法对96份样本进行对照研究,证实其灵敏度有较大提高。结论利用自制的Fe_3O_4@SiO_2磁性纳米颗粒和合适的缓冲液体系,可成功地提取纯度较高的DNA,通过PCR扩增及对比实验表明,该磁性纳米颗粒及其提取工艺经优化后,可用于传染病的体外分子诊断研究。     

SPIO分子探针标记裸鼠肺腺癌移植瘤的磁共振成像及病理学初步研究

目的建立应用超顺磁性氧化铁(SPIO)分子探针氨基硅烷Fe3O4纳米颗粒标记人肺腺癌的裸鼠移植瘤模型,行磁共振成像和病理观察,探讨其临床价值.方法制备氨基硅烷Fe3O4纳米颗粒,分别将标记和未标记肺腺癌细胞株植入裸鼠皮下,观察其成瘤情况,行MR扫描和病理观察.结果标记及未标记纳米分子探针SPIO的肿瘤模型均成功建立,其中前者肿瘤较后者在MR成像中信号强度有明显变化,在T1WI、T2WI、FGR/20°和FGR/70°四个序列中,以FGR/20°变化最明显.病理切片普鲁士兰染色可见肿瘤细胞及坏死组织内有铁染色.结论氨基硅烷Fe3O4纳米颗粒标记人肺腺癌细胞建立裸鼠移植瘤模型稳定可靠,应用磁共振可以对其进行活体监测,提示在临床上具有良好的潜在性应用前景.     

多功能磁性纳米材料在腺样囊性癌肺转移诊断及治疗中的应用

目的探讨四氧化三铁(Fe_3O_4)磁性纳米颗粒在腺样囊性癌肺转移治疗中的作用,为腺样囊性癌肺转移的诊断以及治疗提供依据。方法 Fe_3O_4先经丙烯酸(PAA)修饰,再通过氨基聚乙二醇化马来酰亚胺(NH2-PEGMal)连接叶酸得到表面修饰叶酸的Fe_3O_4(IO-PEG-FA)。随后对纳米材料的尺寸、电位以及形貌进行评价,考察该体系的驰豫时间、升温性能以及肿瘤细胞杀伤能力以及循环肿瘤细胞捕获能力。结果 IO-PEG-FA具有较小的尺寸(约100 nm),有与Fe_3O_4相近的驰豫性能,从而可作为肿瘤转移的诊断材料;具有良好的升温性能,能高效地进行光热杀伤肿瘤细胞。体外循环肿瘤细胞的捕获效率实验表明,该体系有较好的循环肿瘤细胞捕获能力。结论 IO-PEGFA在腺样囊性癌肺转移的诊断以及治疗方面具有很好的前景。     

Fe_3O_4磁性纳米粒子增强青蒿琥酯诱导SKM-1细胞凋亡(英文)

目的:研究磁性纳米粒子Fe_3O_4和青蒿琥酯共聚物对MDS细胞株SKM-1细胞的抑制作用和潜在的机制。方法:用蛋白质印记法检测用或不用共聚物治疗SKM-1细胞的BCL-2、BAX、Caspase-3和Survivin的蛋白表达水平。用流式细胞术检测共聚物诱导的SKM-1细胞的凋亡率。结果:共聚物组的细胞凋亡率明显高于磁性纳米粒子Fe_3O_4组和青蒿琥酯组,磁性纳米粒子Fe_3O_4可以增强青蒿琥酯诱导SKM-1细胞凋亡。蛋白质印记法结果显示,Survivin和BCL-2在青蒿琥酯组表达下调,并且这个下调在青蒿琥酯和磁性纳米粒子Fe_3O_4共聚物组更为明显。与对照组和磁性纳米粒子Fe_3O_4组相比,青蒿琥酯组和共聚物组的BAX水平增高。当青蒿琥酯结合磁性纳米粒子Fe_3O_4后活性Caspase-3水平明显上调。青蒿琥酯和磁性纳米粒子Fe_3O_4共聚物会激发SKM-1细胞凋亡相关基因表达水平的改变,其中BAX的上调与Survivin和BCL-2的下调是主要改变。结论:青蒿琥酯可以诱导SKM-1细胞的凋亡,磁性纳米粒子Fe_3O_4可增强青蒿琥酯诱导细胞凋亡的作用。     

聚乙二醇-聚乙烯亚胺/四氧化三铁纳米磁流体的毒性及其生物相容性

背景:为实现纳米基因药物在治疗肿瘤中实现高靶向性,课题采用聚乙二醇和聚乙烯亚胺修饰的磁性四氧化三铁纳米粒(PEG-PEI/Fe_3O_4)作为基因药物载体,在提高载体载药能力的同时,使载体具有超顺磁性,增加药物靶向性能.目的:评价PEG-PEI/Fe_3O_4纳米磁流体体外和体内毒性.方法:对制备的PEG-PEI/_3O_4纳米磁流体进行表征达到纳米材料水平后,过滤稀释5～20倍培养7702细胞和HpG_2细胞,进行体外MTT毒性试验;通过体内溶血试验和微核试验测定生物相容性和体内毒性.结果与结论:MTT结果显示,PEG-PEI/Fe_3O_4纳米磁流体对7702细胞毒性0～1级,对正常肝细胞无害;PEG-PEI/Fe_3O_4纳米磁流体对HpG_2细胞有轻微的旁观者抑制效应;PEG-PEI/Fe_3O_4纳米磁流体溶血率为0.372%,远小于5%;微核试验结果表明PEG-PEI/Fe_3O_4纳米磁流体无致畸、致突变作用.     

携MAGE靶向金纳米粒光声及超声显像黑色素瘤的实验研究

目的制备抗黑色素瘤相关抗原(MAGE)抗体偶联的载金纳米棒靶向纳米分子探针,探讨其对体外恶性黑色素瘤细胞的靶向性,观察其体外光声成像效果。方法采用双乳化法制备包裹金纳米棒和液态氟碳的聚乳酸-羟基乙酸共聚物(PLGA)纳米粒,碳二亚胺法连接靶向MAGE的单克隆抗体,制备高分子多功能靶向PLGA纳米分子探针,检测其一般物理特性、MAGE抗体与纳米粒的连接情况及其体外寻靶能力,并观察体外光声成像效果。结果成功制备的靶向载金纳米棒多功能纳米分子探针平均粒径(336.40±27.46)nm,平均Zeta电位(-4.34±4.9)m V。MAGE抗体与纳米粒有效连接。体外寻靶能力实验显示黑色素瘤B16细胞株周围有大量靶向纳米探针环绕;光声成像显示随金纳米粒含量增加,其光声信号逐渐增强。结论 MAGE抗体偶联金纳米棒纳米分子探针制备成功,对体外恶性黑色素瘤细胞具有较好的生物活性,细胞靶向性较好,且体外光声成像有明显增强信号,可作为光声成像造影剂,进一步行肿瘤靶向光热治疗。     

两种荧光显微成像系统亚细胞定位的对比

目的:应用高分辨率荧光显微成像系统采集细胞器探针图像,并与激光共聚焦显微成像系统进行对比。方法:实验于2003-05/2004-01在解放军总医院完成。①实验材料:鼠肺毛细血管内皮细胞株(1H11)由上海复旦张江生物公司提供;荧光探针Rhodamine-123,Lucifer Yellow,DiOC6[3],BODIPY(美国Sigma公司)。②细胞培养及荧光探针染色:细胞培养采用含体积分数为0.2胎牛血清的低糖DMEM培养基,密度5×107L-1。选择Rhodamine-123作为细胞线粒体特异性荧光探针,选择DiOC6[3]作为细胞内质网特异性荧光探针,选择BODIPY作为细胞高尔基体特异性荧光探针,选择Lucifer Yellow作为细胞溶酶体探针。前3个探针在完全避光条件下与培养的细胞共同孵育0.5h,后者则共同孵育15h。③高分辨率荧光成像系统的图像采集:线粒体荧光图像采集,选取经Rhodamine-123共孵育完成的细胞,选择激发滤色镜为BP460-490,吸收滤色镜为BA515,分光镜为DM500,另加一绿通道液晶滤光片,激发出Rhodamine-123的荧光。电荷耦合器件采集图像并送入计算机。重复上述步骤,采用DiOC6[3]标记内质网,BODIPY标记高尔基体,Lucifer Yellow标记细胞溶酶体,激发条件同Rhodamine-123。分别采集同一视野靶细胞DiOC6[3]、BODIPY或Lucifer Yellow的荧光图像,完成全部图像采集并储存在计算机中。④激光共聚焦显微成像系统的图像采集:选择经4种探针染色的靶细胞,使用氩离子激光器在488nm激发Rhodamine-123,Rhodamine-123荧光通过配置有530/60-G发射滤光片的通道1探测。重复上述步骤,在488nm激发DiOC6[3]和BODIPY,在457nm激发Lucifer yellow,3种荧光均由通道1探测,后2个探针的发射滤光片的配置为515/30-G,DiOC6[3]选择530/60-G。由光电倍增管接收信号并传输入计算机成像。结果:①高分辨率荧光成像系统所采集图像,靶细胞中由荧光探针Rhodamine-123染色的线粒体呈多个典型的小棒状或卵圆状,聚集在核周;Lucifer yellow染色的溶酶体呈多个非对称球型,在胞浆内随机分布,颗粒尺寸通常大于线粒体;荧光探针DiOC6[3]着色的内质网占据胞浆的很大空间,以囊状聚集为特征;BODIPY特异性地结合在高尔基体上,荧光图像显示围绕在细胞核周围呈条索状。②与高分辨率荧光成像系统比较,激光共聚焦显微成像系统所采集的图像其荧光强度基本相同,但分辨率低、细节显示模糊、胞浆中细胞器的准确分布信息和形态特征显示效果欠佳。结论:两种荧光显微成像系统均可采集到细胞器探针的荧光图像。但高分辨率荧光成像系统采集的荧光图像具有细节清晰、分辨度高、准确显示胞浆中细胞器的分布信息和形态特征等优点。     

An ultrasonic-assisted synthesis of leather-derived luminescent graphene quantum dots: catalytic reduction and switch on–off probe for nitro-explosives

The current research effort demonstrates the ultrasonic-assisted synthesis of highly fluorescent graphene quantum dots (GQDs) of ∼5 nm diameter. First, acid pyrolysis with ultrasonic hydrothermal co-cutting breaks down the coarse graphite into nanometric graphene sheets (GS) and graphene oxide sheets (GOS) with oxygen-rich functionalities. These functionalities were then used to break GOS into graphene oxide nanofibers (GONFs) and graphene oxide quantum dots (GOQDs). Finally, upon reduction, GOQDs lose oxygen linkages to produce fluorescent GQDs (quantum yield up to 27%). The as-developed GQDs were characterized with detailed optical and spectral studies through UV, PL, FTIR, TEM, AFM, XPS, XRD and other techniques. Notably, the synthesized GQDs were catalytically active to serve as a ratiometric fluorescence switch on–off probe for the reduction of toxic nitrophenols. Moreover, the GQDs detected nitrophenol derivatives at lower concentrations than previously reported analytical values. During the real sample analysis of spiked industrial water and exposed soil samples, a high selectivity and sensitivity of the applied method was achieved with a recovery of 99.7% to 101.3% at spiked concentrations of 400 nM to 100 nM, respectively. The detection limit of the photoluminescent probe for paranitrophenol was as low as 10 pM.

The current research effort demonstrates the ultrasonic-assisted synthesis of highly fluorescent graphene quantum dots (GQDs) of ∼5 nm diameter.     

Highly luminescent polyethylene glycol-passivated graphene quantum dots for light emitting diodes

The emergence of fluorescent graphene quantum dots (GQDs) is expected to enhance the usefulness of quantum dots (QDs), in terms of their unique luminescence, photostability, low toxicity, chemical resistance, and electron transport properties. Here we prepared blue-photoluminescent polyethylene glycol GQDs (PEG-GQDs) through PEG surface passivation. The photoluminescence (PL) quantum yield (QY) of PEG-GQDs with 320 nm excitation was about 4.9%, which was higher than that of pure GQDs. The as-fabricated PEG-GQDs with high QY were then used as light-emitting diode (PGQD-LED) emitters, in which the GQDs were incorporated into polymeric host layers in a multilayer electroluminescent device; blue emission with a luminance exceeding 800 cd m⁻² was achieved, thus demonstrating the potential of PEG-GQDs as emitters in electroluminescence applications. Furthermore, the fluorescence mechanism of PEG-GQDs was investigated and proved that the origin of strong fluorescence of PEG-GQDs is associated with the luminescence from intrinsic states. The highly fluorescent PEG-GQDs will allow new devices, such as multicolor LEDs, to be developed with extraordinary properties, by tailoring the intrinsic and extrinsic states.

We prepared blue-photoluminescent polyethylene glycol GQDs (PEG-GQDs) through PEG surface passivation. The PL intensity was stronger than that of pristine GQDs. These were then used as LED emitters and the fluorescence mechanism was investigated.     

One-step synthesis of fluorescent graphene quantum dots as an effective fluorescence probe for vanillin detection

This study proposes an easy bottom-up method for the synthesis of photoluminescent (PL) graphene quantum dots (GQDs) using citric acid as the carbon source. The obtained GQDs were characterized by high-resolution transmission electron microscopy (HRTEM), UV-vis absorption spectroscopy, fluorescence spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). The synthesised GQDs have an average diameter of 4.76 ± 0.96 nm, with a lattice spacing of 0.24 nm. The GQDs exhibit excitation-independent PL emission. The surface of the GQDs has a variety of functional groups (hydroxyl, carboxyl, and ether groups etc.) to enhance its stability and water solubility. In this study, a fluorescent “on–off” sensor is developed for the selective detection of vanillin in chocolates using GQDs as a fluorescent probe. Under optimal conditions, fluorescence intensity of the GQDs has a good linear relationship with the vanillin concentration (0.0–2.1 × 10⁻⁵ mol L⁻¹), with a limit of detection of 2.5 × 10⁻⁸ mol L⁻¹. For detection in real samples, the percent recovery of vanillin and the relative standard deviation were 88.0–108.9% and 0.90–5.4%, respectively. Thus, this GQDs-based method has good accuracy and precision and can be used for vanillin detection in practical applications.

This study proposes an easy bottom-up method for the synthesis of photoluminescent (PL) graphene quantum dots (GQDs) using citric acid as the carbon source.     

A label-free electrochemical platform for the highly sensitive detection of hepatitis B virus DNA using graphene quantum dots

Based on the strong interaction between single-stranded DNA and graphene material, we have designed a simple but smart electrochemical platform to detect HBV-DNA by using a graphene quantum dot (GQD) modified glassy carbon electrode coupled with specific sequence DNA molecules as probes. The probe DNA is designed to be complementary to the HBV-DNA, when the probe DNA is strongly bound to the surface of the GQD modified electrode the transfer of an electron from the electrode to the electrochemically active species K₃[Fe(CN)₆] will become difficult. Nevertheless, if the target HBV-DNA is found in the test solution, the probe DNA will bind with the target HBV-DNA instead of GQDs. As a result, the obtained peak currents of K₃[Fe(CN)₆] will have a different degree of increase with the different concentrations of the target HBV-DNA. In particular, the proposed sensor exhibits high sensitivity with a detection limit of 1 nM, and the linear detection range is from 10 nM to 500 nM. Additionally, the sensor could be used in detecting other probe DNA, which may have potential applications in the future.

Based on the interaction between single-stranded probe DNA and graphene quantum dots (GQDs), we have designed a simple but smart electrochemical platform to detect HBV-DNA by using GQDs modified glassy carbon electrode coupled with probe DNA.     

磁性/荧光量子点双功能纳米粒子双标记对大鼠骨髓间充质干细胞生物学特性的影响

目的：利用磁性/荧光量子点双功能纳米粒子双标记大鼠骨髓间充质干细胞（BM-SCs）,探讨其对BMSCs生物学特性的影响。方法：分离、纯化及培养大鼠BMSCs。制备二氧化硅（SiO2）包裹的含四氧化三铁（Fe3O4）和碲化镉（CdTe）荧光量子点的磁性及荧光双功能纳米粒子Fe3O4@CdTe@SiO2,利用铁浓度为25 mg/L的Fe3O4@CdTe@SiO2双标记BMSCs,未标记的BMSCs作为对照组。采用细胞计数（CCK-8）试剂盒检测BMSCs细胞毒性和增殖能力,台盼蓝拒染测细胞活力,成骨、成脂诱导检测细胞多向分化能力,评价双标记对BMSCs生物学特性的影响。荧光显微镜和普鲁士蓝染色观察诱导分化后Fe3O4@CdTe@SiO2双标记情况。结果：荧光显微镜下可见双标记组细胞内Fe3O4@CdTe@SiO2纳米粒子显示为红色荧光,荧光和磁性双标记率均达到90%以上。Fe3O4@CdTe@SiO2双标记后细胞存活率为（94±5）%。Fe3O4@CdTe@SiO2对BMSCs无明显细胞毒性,对BMSCs的成脂、成骨分化潜能无明显影响。结论：磁性/荧光量子点双功能纳米粒子（Fe3O4@CdTe@SiO2纳米粒子）双标记对大鼠BMSCs安全有效,对BMSCs的生物学特性无明显影响,有望为MRI和光学成像活体示踪BMSCs提供技术基础。     

Simple preparation of graphene quantum dots with controllable surface states from graphite

Graphite is economic and earth-abundant carbon precursor for preparing graphene quantum dots (GQDs). Here, we report a facile and green approach to produce GQDs from graphite flakes via a pulsed laser ablation (PLA) method assisted by high-power sonication. A homogeneous dispersion of graphite flakes, caused by high-power sonication during PLA, leads to the formation of GQDs following a laser fragmentation in liquid (LFL) rather than laser ablation in liquid (LAL) mechanism. The final product of GQDs exhibits the distinct structural, chemical, and optical properties of pristine graphene itself. However, graphene oxide quantum dots (GOQDs) with abundant surface oxygen-rich functional groups are readily formed from graphite flakes when high-power sonication is not employed during the PLA process. GQDs and GOQDs show a significantly different luminescence nature. Hence, selective production of either functional GQDs or GOQDs can be achieved by simply turning the high-power sonication during the PLA process on and off. We believe that our modified PLA process proposed in this work will further open up facile and simple routes for designing functional carbon materials.

The proposed technique enables selectively producing graphene quantum dots (on-GQDs) and graphene oxide quantum dots (off-GOQDs) by depending on the applying sonication during the pulsed laser ablation process.     

In vivo targeting of breast cancer with a vasculature-specific GQDs/hMSN nanoplatform

According to our previous experiment, graphene quantum dots capped in hollow mesoporous silica nanoparticles, denoted as GQDs@hMSN, and its conjugates exhibited great potential for medical applications due to their commendable biocompatibility. Due to the fluorescence and structural stability, and enormous porosity, polyethylene glycol (PEG) modified GQDs@hMSN (GQDs@hMSN-PEG) is a good candidate in a drug carrying and delivery system. However, the goal of targeted drug delivery couldn''t be achieved simply by utilizing the enhanced permeability and retention (EPR) effect of tumors. In this study, GQDs@hMSN-PEG was further functionalized with vascular endothelial growth factor antibodies (VEGF Abs) for VEGF targeting of breast tumors. Doxorubicin (DOX) was loaded into GQDs@hMSN-VEGF Abs with a drug loading capacity of 0.80 mg DOX per mg GQDs@hMSN. With GQDs as the fluorescent source, GQDs@hMSN-VEGF Abs demonstrated strong fluorescence intensity in VEGF-positive cells. Results from in vitro and in vivo targeting experiments indicated that GQDs@hMSN-VEGF Abs had high specificity on tumor vasculature, and it could be used as an image-guidable, tumor-selective delivery nanoplatform for breast cancer.

According to our previous experiment, graphene quantum dots capped in hollow mesoporous silica nanoparticles, denoted as GQDs@hMSN, and its conjugates exhibited great potential for medical applications due to their commendable biocompatibility.     

Synthesis and spectroscopic studies of functionalized graphene quantum dots with diverse fluorescence characteristics

In this research, we report a facile method for synthesizing a series of carboxyl functionalized graphene quantum dots (GQDs) using graphite flakes (300 meshes) as raw material. These highly luminescent GQDs emitted blue, light blue, green, yellow, and red light (400–700 nm intensity peaks) under ultraviolet irradiation conditions, while exhibiting quantum yields in the range of 50–70%. The products were comprehensively characterized using ultraviolet-visible, photoluminescence, infrared, Raman, and dynamic light scattering spectroscopies. The GQDs were found to remain highly stable against photobleaching when stored over a prolonged period of more than three months. The proposed method for the synthesis of high quality, multicolor GQDs can be utilized to extend the application of these nanoparticles to molecular biotechnology and bioengineering; for example, the immobilization of cancer markers on their surface. As such, carboxylic acid groups present on the surface of these GQDs help create complexes for in vivo sensing applications.

In this research, we report a facile method for synthesizing a series of carboxyl functionalized graphene quantum dots (GQDs) using graphite flakes (300 meshes) as raw material.     

An eco-friendly imprinted polymer based on graphene quantum dots for fluorescent detection of p-nitroaniline

An eco-friendly fluorescent molecularly imprinted polymer anchored on the surface of graphene quantum dots (GQDs@MIP) was developed with an efficient sol–gel polymerization for highly sensitive and selective determination of p-nitroaniline (p-NA). The GQDs@MIP was characterized in detail by Fourier-transform infrared, fluorescence spectrometer, scanning electron microscope, transmission electron microscope and ultraviolet spectrophotometer. The results showed that the imprinted layer was successfully grafted on the surface of the GQDs. The fluorescence of the GQDs@MIP is efficiently quenched when p-NA recombines with the imprinting sites based on the photo-induced electron transfer fluorescence quenching mechanism. A good linear relationship was obtained between the fluorescence quenching efficiency of the GQDs@MIP and the concentration of p-NA in the range of 0–15.0 μM with a correlation coefficient of 0.99. The practicability of the proposed method in real samples was successfully evaluated through monitoring p-NA in water and fish samples with satisfactory recovery. The developed method provides a feasible and eco-friendly strategy to fabricate MIPs anchored on GQDs with good fluorescence properties for sensitive detection of organic pollutants in complex samples.

An eco-friendly fluorescent molecularly imprinted polymer anchored on the surface of graphene quantum dots (GQDs@MIP) was developed with an efficient sol–gel polymerization for highly sensitive and selective determination of p-nitroaniline (p-NA).     

Post-synthetic modification of graphene quantum dots bestows enhanced biosensing and antibiofilm ability: efficiency facet

Graphene quantum dots (GQDs) are a luminescent class of carbon nanomaterials with a graphene-like core structure, possessing quantum confinement and edge effects. They have gained importance in the biological world due to their inherent biocompatibility, good water dispersibility, excellent fluorescence and photostability. The improved properties of GQDs require the logical enactment of functional groups, which can be easily attained through post-synthetic non-covalent routes of modification. In this regard, the present work has for the first time employed a simple one-pot post-modification method utilizing the salt of amino caproic acid, an FDA approved reagent. The adsorption of the modifier on GQDs with varying weight ratios is characterized through DLS, zeta potential, Raman, absorption and fluorescence spectroscopy. A decrease of 20% in the fluorescence intensity with an increase in the modifier ratio from 1 to 1000 and an increased DLS size as well as zeta potential demonstrate the efficient modification as well as higher stability of the modified GQDs. The modified GQDs with a high weight ratio (1 : 100) of the modifier showed superior ability to sense dopamine, a neurotransmitter, as well as competent biofilm degradation ability. The modified GQDs could sense more efficiently than pristine GQDs, with a sensitivity as low as 0.06 μM (limit of detection) and 90% selectivity in the presence of other neurotransmitters. The linear relationship showed a decrease in the fluorescence intensity with increasing dopamine concentration from 0.0625 μM to 50 μM. Furthermore, the efficiency of the modified GQDs was also assessed in terms of their antibiofilm effect against Staphylococcus aureus. The unmodified GQDs showed only 10% disruption of the adhered bacterial colonies, while the modified GQDs (1 : 100) showed significantly more than 60% disruption of the biofilm, presenting the competency of the modified GQDs. The unique modifications of GQDs have thus proven to be an effective method for the proficient utilization of zero-dimensional carbon nanomaterials for biosensing, bioimaging, antibacterial and anti-biofilm applications.

The present work highlights a novel post-synthetic modification route for graphene quantum dots, which was found to be efficient for both the biosensing of dopamine as well as Staphylococcus aureus biofilm degradation.