[en] Objective: To study the therapeutic efficacy of radioimmunotherapy of ¹³¹I-human anti-HBsAg Fab via different routes of administration. Methods: The human hepatoma bearing nude mice we reinjected with ¹³¹I-human anti-HBsAg Fab intra-tumor (IT) and intra-peritoneum (IP). Biodistribution was measured on the 5th day. The tumor growth inhibition rate was determined by measurement of tumor volume. Results: In the IT-treated mice, tumor uptake of ¹³¹I-human anti-HBsAg Fab was four-fold greater than in the IP-treated mice, and normal organ uptake was half of that in the IP-treated mice. At the 3rd week after the infusion, the tumor growth inhibition rate in IT-treated mice was higher than that in the IP-treated mice. Conclusions: Intratumoral administration of ¹³¹I-human anti-HBsAg Fab makes high level of radioactivity retained in tumor with significantly lower radioactivity retained in normal tissues, and provides a more effective regional therapy

[en] A highly sensitive quantum dot (QD)–based western blot assay with extended dynamic range was developed. Bimodal size distribution QD (BQ) immunoprobes composed of small size single QD (7.3 nm) and big size QD nanobead (QB) (82.9 nm) were employed for fluorescent western blot immunoassay on a membrane. Small size QD immunoprobes contributed to wider dynamic range of assay, while big size QB immunoprobes provided higher detection sensitivity. This BQ-based western blot assay can achieve a wide dynamic range (from 7.8 to 4000 ng IgG) and is nearly as sensitive as commercial available ultrasensitive chemiluminescent methods, just using a simple gel imager with UV light (365 nm) excitation and red light filter (610 nm). The fluorescent signals of BQ western blot were stable for 10 min, while chemiluminescent signals faded after 1 min. Moreover, this BQ immunoprobe was utilized for the detection of housekeeping protein and specific target proteins in complex cell lysate samples. The limit of detection of housekeeping protein is 0.25 μg of cell lysate, and the signal intensities were proportional to loading protein amount in a wide range from 0.61 to 80 μg. We believe that this new strategy of bimodal size distribution nanoparticles can also be expanded for other functional nanoparticle-based biological assays to improve the sensitivity and extend the dynamic range.

[en] A fluorometric and magnetic resonance (MR) dual-modal detection scheme is presented for determination of ascorbic acid (AA). It is based on the use of a blended Au/MnO₂@BSA mixture that was prepared via a biomimetic strategy, using bovine serum albumin (BSA) as the template at physiological temperature. The MnO₂@BSA fraction (one part of the composite) is not susceptible to MR but can be degraded to MR-active compounds upon a redox reaction with even ultralow concentrations of AA. In parallel, the blended Au/MnO₂@BSA recovers its fluorescence because MnO₂@BSA acts as a quencher of the fluorescence of circumjacent Au@BSA (the other part of the composite). Fluorescence typically is measured at excitation/emission wavelengths of 470/625 nm. Leveraging on this redox reaction between MnO₂ and AA, a dual-mode detection scheme for AA was developed. Both the fluorescence and the MR signal increase with the concentration of AA. The lowest limit for the detection of AA is 0.6 μM in the fluorometric mode and 0.4 μM in the MR mode. Analysis of AA-spiked serum samples showed that the recoveries obtained by either the fluorometric and MR mode can reach 94%. This is the first report of the use of blended nanoparticles with their inherent cross-validation regularity.

.