ABSTRACT
Combination of responsive microgels and photonic resonant nanostructures represents an intriguing technological tool for realizing tunable and reconfigurable platforms, especially useful for biochemical sensing applications. Interaction of light with microgel particles during their swelling/shrinking dynamics is not trivial because of the inverse relationships between their size and refractive index. In this work, we propose a reliable analytical model describing the optical properties of closed-packed assembly of surface-attached microgels, as a function of the external stimulus applied. The relationships between the refractive index and thickness of the equivalent microgel slab are derived from experimental observations based on conventional morphological analysis. The model is first validated in the case of temperature responsive microgels integrated on a plasmonic lab-on-fiber optrode, and also implemented in the same case study for an optical responsivity optimization problem. Overall, our model can be extended to other photonic platforms and different kind of microgels, independently from the nature of the stimulus inducing their swelling.
ABSTRACT
Precision medicine is continuously demanding for novel point of care systems, potentially exploitable also for in-vivo analysis. Biosensing probes based on Lab-On-Fiber Technology have been recently developed to meet these challenges. However, devices exploiting standard label-free approaches (based on ligand/target molecule interaction) suffer from low sensitivity in all cases where the detection of small molecules at low concentrations is needed. Here we report on a platform developed through the combination of Lab-On-Fiber probes with microgels, which are directly integrated onto the resonant plasmonic nanostructure realized on the fiber tip. In response to binding events, the microgel network concentrates the target molecule and amplifies the optical response, leading to remarkable sensitivity enhancement. Moreover, by acting on the microgel degrees of freedom such as concentration and operating temperature, it is possible to control the limit of detection, tune the working range as well as the response time of the probe. These unique characteristics pave the way for advanced label-free biosensing platforms, suitably reconfigurable depending on the specific application.
ABSTRACT
The objective of this study was to determine if pregnancy specific protein-B (PSPB) and estrone sulfate (E(1)SO(4)) could be used to determine pregnancy status in fallow deer (Dama dama ). Forty mature does were synchronized for estrus with an intravaginal progesterone-releasing device (CIDR) and then artificially inseminated via laparoscopy with frozen semen on one day. Ultrasound examination and jugular blood sampling were done 49 days later. Transrectal ultrasonography was done to presumptively determine the pregnancy status at the time of blood sampling. Serum estrone sulfate concentrations were significantly (P < 0.05) greater in pregnant (n=31) than nonpregnant (n=9) females at 49 days of gestation (166.7 +/- 25.9 pg/ml vs 36.3 +/- 11.1 pg/ml, respectively). The percentage of [(125)I]PSPB bound was significantly (P < 0.01) lower when sera of pregnant (n=29) versus nonpregnant (n=9) females was added to RIA tubes (63.7 +/- 1.6% vs 98.1 +/- 1.6%, respectively). There were 30 fawns born from the group of females that were diagnosed pregnant based on ultrasound. We conclude that estrone sulfate and PSPB can be used to determine pregnancy status in fallow deer at 49 days of gestation.
ABSTRACT
Estrus and ovulation of mature fallow does (n=155) on two North American farms were synchronized by intravaginal silastic devices containing 0.3 g progesterone (CIDR-type G) for 14 d. Each of 151 does received laparoscopic intrauterine inseminations of either 50x10(6) (n=125) or 25x10(6) (n=26) frozen-thawed spermatozoa, 65 to 68 h after CIDR device withdrawal. Four does received intrauterine inseminations per vaginam of 50x10(6) spermatozoa 68 to 69 hours after CIDR device withdrawal. Semen from crossbred Dama dama damaxDama dama mesopotamica sires was collected in New Zealand by electroejaculation. The overall pregnancy rate to artificial insemination, as assessed by rectal ultrasonography at Day 45, was 67.7%. The pregnancy rates for does receiving laparoscopic inseminations were 58.2% (Texas; 50x10(6) spermatozoa; n=79 does); 80.8% (Texas; 25x10(6) spermatozoa; n=26 does) and 76.1% (New York; 50x10(6) spermatozoa; n=46 does). Three of the four does receiving intrauterine inseminations per vaginam became pregnant to the frozen-thawed semen.