用适配体修饰纳米金做共振瑞利散射光谱探针检测妥布霉素

用硼氢化钠还原氯金酸制备了金纳米粒子(GN)，用妥布霉素适配体(Apt)修饰GN可获得较稳定的Apt-GN探针。在pH 6.8 Na₂HPO₄-NaH₂PO₄(PBS)缓冲液及NaCl存在下，Apt-GN探针稳定而不聚集;当有妥布霉素(Tbc)存在时，它与Apt-GN探针中的Apt特异性结合并释放出纳米金，纳米金在NaCl作用下聚集，导致体系在368 nm处的共振瑞利散射光增强。在选定实验条件下，368 nm处的共振散射峰强度的增大值ΔI与抗生素妥布霉素(Tbc)浓度在1.9～58.3 ng·mL-1范围内呈良好线性关系，其线性回归方程为ΔI=35.3c-23，检出限为0.8 ng·mL-1 妥布霉素。分别对10.0，20.0和30.0 ng·mL-1 Tbc平行测定5次，求得其相对标准偏差分别为6.8%，5.0%和4.4%。考察了共存离子对测定38.9 ng·mL-1 妥布霉素的干扰情况。结果表明，当相对误差在±10%以内，80倍Zn2+;40倍L-谷氨酸，Cu2+，Mg2+，Ca2+;20倍葡萄糖、盐酸土霉素;10倍L-苯丙氨酸、甘氨酸;2倍L-天冬氨酸;6倍HSA和BSA不干扰测定。这说明本方法具有较好的选择性。该法用于分析测定妥布霉素滴眼液中的妥布霉素含量，结果令人满意，相对标准偏差在6.5%～7.6%之间，回收率在95.0%～107%之间。

Resonance Rayleigh Scattering Determination of Trace Tobramycin Using Aptamer-Modified Nanogold as Probe

Nanogold (NG) was prepared using NaBH₄ reduction of HAuCl₄. The NG was modified by the tobramycin-aptamer to obtain a stable Apt-NG probe for tobramycin. The three aptamers containing 15, 21 and 27 bases were examined, and results showed that the aptamer with 21 bases was best and was chosen for use. In pH 6.8 PBS buffer solution and in the presence of NaCl, the Apt-GN probes were not aggregated. When tobramycin was added, it reacted with the Apt of Apt-NG probe to form a very stable Apt-Tbc complex and released NGs that were aggregated into big particles under the action of NaCl with three resonance Rayleigh scattering peaks at 285, 368 and 525 nm respectively. The resonance Rayleigh scattering peak increased at 368 nm due to the formation of big NG particles from the probe. The effect of pH buffer solution, its volume, and Apt-GN probe concentration on the ΔI value was considered. A 200 μL pH 6.8 PBS buffer solution and 19.1 nmol·L-3 Apt-GN, giving max ΔI value, were chosen for use. Under the chosen conditions, the increased resonance Rayleigh scattering intensity ΔI₃₆₈ nm was linear with Tbc concentration in the range of 1.9～58.3 ng·mL-3, with a regress equation of ΔI=35.3ｃ-23 and a detection limit of 0.8 ng·mL-3 Tbc. A 10.0, 20.0 and 30.0 ng·mL-3 Tbc was determined five times respectively, and the relative standard deviations were 6.8%, 5.0% and 4.4%. The influence of some foreign substances was examined on the determination of 38.9 ng·mL-3 Tbc, within ±10% related error. Results showed that a 80 times of Zn2+, 40 times of L-glutamic acid, Cu2+, Mg2+ and Ca2+, 20 times of glucose and terramycin, 10 times of L-phenylalanine and glycin, 2 times of L-aspartic acid, and 6 times of bovine serum albumin (BSA) and human serum albumin (HSA) do not interfere with the RRS determination of Tbc. The results showed that this aptamer-nanogold RRS method is of good selectivity. Tbc in real sample was analyzed, and the analytical result was in agreement with that of reference results, with a relative standard deviation of 6.5%～7.6% and a recovery of 95.0%～107%.