Limits...
In vivo biosensing via tissue-localizable near-infrared-fluorescent single-walled carbon nanotubes.

Iverson NM, Barone PW, Shandell M, Trudel LJ, Sen S, Sen F, Ivanov V, Atolia E, Farias E, McNicholas TP, Reuel N, Parry NM, Wogan GN, Strano MS - Nat Nanotechnol (2013)

Bottom Line: The half-life for liver retention is 4 h, with sensors clearing the lungs within 2 h after injection, thus avoiding a dominant route of in vivo nanotoxicology.After localization within the liver, it is possible to follow the transient inflammation using nitric oxide as a marker and signalling molecule.Finally, we demonstrate that alginate-encapsulated single-walled carbon nanotubes can function as implantable inflammation sensors for nitric oxide detection, with no intrinsic immune reactivity or other adverse response for more than 400 days.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA [2] Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.

ABSTRACT
Single-walled carbon nanotubes are particularly attractive for biomedical applications, because they exhibit a fluorescent signal in a spectral region where there is minimal interference from biological media. Although single-walled carbon nanotubes have been used as highly sensitive detectors for various compounds, their use as in vivo biomarkers requires the simultaneous optimization of various parameters, including biocompatibility, molecular recognition, high fluorescence quantum efficiency and signal transduction. Here we show that a polyethylene glycol ligated copolymer stabilizes near-infrared-fluorescent single-walled carbon nanotubes sensors in solution, enabling intravenous injection into mice and the selective detection of local nitric oxide concentration with a detection limit of 1 µM. The half-life for liver retention is 4 h, with sensors clearing the lungs within 2 h after injection, thus avoiding a dominant route of in vivo nanotoxicology. After localization within the liver, it is possible to follow the transient inflammation using nitric oxide as a marker and signalling molecule. To this end, we also report a spatial-spectral imaging algorithm to deconvolute fluorescence intensity and spatial information from measurements. Finally, we demonstrate that alginate-encapsulated single-walled carbon nanotubes can function as implantable inflammation sensors for nitric oxide detection, with no intrinsic immune reactivity or other adverse response for more than 400 days.

Show MeSH
In vivo sensor quenching due to inflammationa, Inflamed (RcsX treated) and control (healthy) mice imaged in situ 30 minutes after tail vein injection of PEG-(AAAT)7-SWNT (200 μL injection of 50 mg L−1 SWNT) with their livers exposed then the excised liver imaged immediately following sacrifice, displaying the SWNT quenching that is observed in the inflamed animal (scale bars 4 mm). b, Chart showing quantification of SWNT fluorescence, including an extra control of a RcsX treated (inflamed) mouse that received a tail vein injection of saline. (n = 10, error bars are s.e.m.) c, Graph of SWNT fluorescence distribution in mouse livers shown in a and b.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4066962&req=5

Figure 4: In vivo sensor quenching due to inflammationa, Inflamed (RcsX treated) and control (healthy) mice imaged in situ 30 minutes after tail vein injection of PEG-(AAAT)7-SWNT (200 μL injection of 50 mg L−1 SWNT) with their livers exposed then the excised liver imaged immediately following sacrifice, displaying the SWNT quenching that is observed in the inflamed animal (scale bars 4 mm). b, Chart showing quantification of SWNT fluorescence, including an extra control of a RcsX treated (inflamed) mouse that received a tail vein injection of saline. (n = 10, error bars are s.e.m.) c, Graph of SWNT fluorescence distribution in mouse livers shown in a and b.

Mentions: Having established the detectability of PEG-(AAAT)7-SWNT in mouse livers, we assessed the ability of the sensor to detect NO produced during inflammation in vivo. For this purpose, we could have used any mouse model, but chose the SJL mouse due to its intense inflammatory response resulting in massive overproduction of NO over a predictable time course after induction by an injection of RcsX tumor cells, as previously described35. Accordingly, mice were injected intraperitoneally with RcsX cells35 or saline (n=10, repeated once with n=5). After 12 days, PEG-(AAAT)7-SWNT was injected into the tail vein of anesthetized mice, and 30 minutes later a cut in the abdominal cavity exposed the liver to allow in situ imaging (Fig. 4a). Immediately thereafter the animal was sacrificed, the liver excised and the isolated organ imaged a second time. Comparison of in situ images shows that livers of control animals clearly displayed fluorescence, whereas it was undetectable in inflamed organs of RcsX treated mice. In contrast, images of excised livers show that similar levels of SWNT fluorescence are present in both RcsX and control animals. We conclude that absence of fluorescence in the in situ images was attributable to NO generated during inflammation, since SWNT was clearly present in the organs as shown by fluorescence in excised organs. The rapid recovery of PEG-(AAAT)7-SWNT fluorescence after exposure to NO (Fig. 1c) is consistent with this interpretation. Quantification of these data was performed (Fig. 4b) and showed a 55% difference between pre- and post-sacrifice fluorescence in inflamed tissues compared to 3% difference in controls. Fluorescence distribution data shows the similarity between tissue of control mice without SWNT and the signal detected in the inflamed animals with injected SWNT (39 and 54 a.u. mm−2 compared to 153 a.u. mm−2 for non-inflamed mice with SWNT) while the excised liver samples for both inflamed and non-inflamed mice have similar standard deviations (48.14 and 43.41 a.u.) and peak values (148 and 158 a.u.). A limitation of this study is the need to expose the liver for in situ imaging, which we propose to address by further optimization of the SWNT to enable deeper tissue imaging or the use of a laproscopic probe to allow imaging with an even smaller incision than currently used.


In vivo biosensing via tissue-localizable near-infrared-fluorescent single-walled carbon nanotubes.

Iverson NM, Barone PW, Shandell M, Trudel LJ, Sen S, Sen F, Ivanov V, Atolia E, Farias E, McNicholas TP, Reuel N, Parry NM, Wogan GN, Strano MS - Nat Nanotechnol (2013)

In vivo sensor quenching due to inflammationa, Inflamed (RcsX treated) and control (healthy) mice imaged in situ 30 minutes after tail vein injection of PEG-(AAAT)7-SWNT (200 μL injection of 50 mg L−1 SWNT) with their livers exposed then the excised liver imaged immediately following sacrifice, displaying the SWNT quenching that is observed in the inflamed animal (scale bars 4 mm). b, Chart showing quantification of SWNT fluorescence, including an extra control of a RcsX treated (inflamed) mouse that received a tail vein injection of saline. (n = 10, error bars are s.e.m.) c, Graph of SWNT fluorescence distribution in mouse livers shown in a and b.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4066962&req=5

Figure 4: In vivo sensor quenching due to inflammationa, Inflamed (RcsX treated) and control (healthy) mice imaged in situ 30 minutes after tail vein injection of PEG-(AAAT)7-SWNT (200 μL injection of 50 mg L−1 SWNT) with their livers exposed then the excised liver imaged immediately following sacrifice, displaying the SWNT quenching that is observed in the inflamed animal (scale bars 4 mm). b, Chart showing quantification of SWNT fluorescence, including an extra control of a RcsX treated (inflamed) mouse that received a tail vein injection of saline. (n = 10, error bars are s.e.m.) c, Graph of SWNT fluorescence distribution in mouse livers shown in a and b.
Mentions: Having established the detectability of PEG-(AAAT)7-SWNT in mouse livers, we assessed the ability of the sensor to detect NO produced during inflammation in vivo. For this purpose, we could have used any mouse model, but chose the SJL mouse due to its intense inflammatory response resulting in massive overproduction of NO over a predictable time course after induction by an injection of RcsX tumor cells, as previously described35. Accordingly, mice were injected intraperitoneally with RcsX cells35 or saline (n=10, repeated once with n=5). After 12 days, PEG-(AAAT)7-SWNT was injected into the tail vein of anesthetized mice, and 30 minutes later a cut in the abdominal cavity exposed the liver to allow in situ imaging (Fig. 4a). Immediately thereafter the animal was sacrificed, the liver excised and the isolated organ imaged a second time. Comparison of in situ images shows that livers of control animals clearly displayed fluorescence, whereas it was undetectable in inflamed organs of RcsX treated mice. In contrast, images of excised livers show that similar levels of SWNT fluorescence are present in both RcsX and control animals. We conclude that absence of fluorescence in the in situ images was attributable to NO generated during inflammation, since SWNT was clearly present in the organs as shown by fluorescence in excised organs. The rapid recovery of PEG-(AAAT)7-SWNT fluorescence after exposure to NO (Fig. 1c) is consistent with this interpretation. Quantification of these data was performed (Fig. 4b) and showed a 55% difference between pre- and post-sacrifice fluorescence in inflamed tissues compared to 3% difference in controls. Fluorescence distribution data shows the similarity between tissue of control mice without SWNT and the signal detected in the inflamed animals with injected SWNT (39 and 54 a.u. mm−2 compared to 153 a.u. mm−2 for non-inflamed mice with SWNT) while the excised liver samples for both inflamed and non-inflamed mice have similar standard deviations (48.14 and 43.41 a.u.) and peak values (148 and 158 a.u.). A limitation of this study is the need to expose the liver for in situ imaging, which we propose to address by further optimization of the SWNT to enable deeper tissue imaging or the use of a laproscopic probe to allow imaging with an even smaller incision than currently used.

Bottom Line: The half-life for liver retention is 4 h, with sensors clearing the lungs within 2 h after injection, thus avoiding a dominant route of in vivo nanotoxicology.After localization within the liver, it is possible to follow the transient inflammation using nitric oxide as a marker and signalling molecule.Finally, we demonstrate that alginate-encapsulated single-walled carbon nanotubes can function as implantable inflammation sensors for nitric oxide detection, with no intrinsic immune reactivity or other adverse response for more than 400 days.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA [2] Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.

ABSTRACT
Single-walled carbon nanotubes are particularly attractive for biomedical applications, because they exhibit a fluorescent signal in a spectral region where there is minimal interference from biological media. Although single-walled carbon nanotubes have been used as highly sensitive detectors for various compounds, their use as in vivo biomarkers requires the simultaneous optimization of various parameters, including biocompatibility, molecular recognition, high fluorescence quantum efficiency and signal transduction. Here we show that a polyethylene glycol ligated copolymer stabilizes near-infrared-fluorescent single-walled carbon nanotubes sensors in solution, enabling intravenous injection into mice and the selective detection of local nitric oxide concentration with a detection limit of 1 µM. The half-life for liver retention is 4 h, with sensors clearing the lungs within 2 h after injection, thus avoiding a dominant route of in vivo nanotoxicology. After localization within the liver, it is possible to follow the transient inflammation using nitric oxide as a marker and signalling molecule. To this end, we also report a spatial-spectral imaging algorithm to deconvolute fluorescence intensity and spatial information from measurements. Finally, we demonstrate that alginate-encapsulated single-walled carbon nanotubes can function as implantable inflammation sensors for nitric oxide detection, with no intrinsic immune reactivity or other adverse response for more than 400 days.

Show MeSH