Carl-Johan Carling | University of California, San Diego (original) (raw)
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Papers by Carl-Johan Carling
Journal of Controlled Release, 2015
Light is an excellent means to externally control the properties of materials and small molecules... more Light is an excellent means to externally control the properties of materials and small molecules for many applications. Light's ability to initiate chemistries largely independent of a material's local environment makes it particularly useful as a bio-orthogonal and on-demand trigger in living systems. Materials responsive to UV light are widely reported in the literature; however, UV light has substantial limitations for in vitro and in vivo applications. Many biological molecules absorb these energetic wavelengths directly, not only preventing substantial tissue penetration but also causing detrimental photochemical reactions. The more innocuous nature of long-wavelength light (>400nm) and its ability at longer wavelengths (600-950nm) to effectively penetrate tissues is ideal for biological applications. Multi-photon processes (e.g. two-photon excitation and upconversion) using longer wavelength light, often in the near-infrared (NIR) range, have been proposed as a means of avoiding the negative characteristics of UV light. However, high-power focused laser light and long irradiation times are often required to initiate photorelease using these inefficient non-linear optical methods, limiting their in vivo use in mammalian tissues where NIR light is readily scattered. The development of materials that efficiently convert a single photon of long-wavelength light to chemical change is a viable solution to achieve in vivo photorelease. However, to date only a few such materials have been reported. Here we review current technologies for photo-regulated release using photoactive organic materials that directly absorb visible and NIR light.
Chemical communications (Cambridge, England), Jan 25, 2015
Exposure to UV light generates a ring-closed isomer of a diarylethene, which undergoes very slow ... more Exposure to UV light generates a ring-closed isomer of a diarylethene, which undergoes very slow bond breaking and release even after the light is turned off. The rate of release is increased by exposing the isomer to UV and/or visible light.
Angewandte Chemie International Edition, 2010
We introduce a means of efficiently photo-uncaging active compounds from amino-1,4-benzoquinone i... more We introduce a means of efficiently photo-uncaging active compounds from amino-1,4-benzoquinone in aqueous environments. Aqueous photochemistry of this photocage with one-photon red light is typically not efficient unless the photocaged molecules are allowed to assemble into nanoparticles. A variety of biologically active molecules were functionalized with the photocage and subsequently formulated into water-dispersible nanoparticles. Red light irradiation through various mammalian tissues achieved efficient photo-uncaging. Co-encapsulation of NIR fluorescent dyes and subsequent photomodulation provides a NIR fluorescent tool to assess both particle location and successful photorelease.
Controlling chemistry in space and time has offered scientists and engineers powerful tools for r... more Controlling chemistry in space and time has offered scientists and engineers powerful tools for research and technology. For example, on-demand photo-triggered activation of neurotransmitters has revolutionized neuroscience. Non-invasive control of the availability of bioactive molecules in living organisms will undoubtedly lead to major advances; however, this requires the development of photosystems that efficiently respond to regions of the electromagnetic spectrum that innocuously penetrate tissue. To this end, we have developed a polymer that photochemically degrades upon absorption of one photon of visible light and demonstrated its potential for medical applications. Particles formulated from this polymer release molecular cargo in vitro and in vivo upon irradiation with blue visible light through a photoexpansile swelling mechanism.
Near-infrared (NIR) light-triggered release from polymeric capsules could make a major impact on ... more Near-infrared (NIR) light-triggered release from polymeric capsules could make a major impact on biological research by enabling remote and spatiotemporal control over the release of encapsulated cargo. The few existing mechanisms for NIR-triggered release have not been widely applied because they require custom synthesis of designer polymers, high-powered lasers to drive inefficient two-photon processes, and/or coencapsulation of bulky inorganic particles. In search of a simpler mechanism, we found that exposure to laser light resonant with the vibrational absorption of water (980 nm) in the NIR region can induce release of payloads encapsulated in particles made from inherently non-photo-responsive polymers. We hypothesize that confined water pockets present in hydrated polymer particles absorb electromagnetic energy and transfer it to the polymer matrix, inducing a thermal phase change. In this study, we show that this simple and highly universal strategy enables instantaneous and controlled release of payloads in aqueous environments as well as in living cells using both pulsed and continuous wavelength lasers without significant heating of the surrounding aqueous
solution.
Sun block for nanoparticles: Unintentional photorelease triggered by UV light is a problem in pho... more Sun block for nanoparticles: Unintentional photorelease triggered by UV light is a problem in photodynamic therapy. Encapsulating upconverting nanoparticles containing photoswitches in a UV-blocking amphiphilic polymer shuts down the one-photon process and only allows two-photon-driven photochemistry. Thus UV light is blocked while NIR light can reach the nanoparticle core and trigger photorelease.
One of the primary disadvantages of organic photochemistry is the need for high-energy UV light, ... more One of the primary disadvantages of organic photochemistry is the need for high-energy UV light, light that has many detrimental qualities. A viable solution to this problem is the use of upconverting nanoparticles (UCNP) that can locally convert near infrared (NIR) laser light into UV light or visible light of sufficient energy to drive organic photoreactions.
A novel amphiphilic photochromic copolymer P1-o consisting of a hydrophilic poly(N-isopropylacryl... more A novel amphiphilic photochromic copolymer P1-o consisting of a hydrophilic poly(N-isopropylacrylamide) backbone and thermally irreversible photochromic and hydrophobic 1,2-dithienylethene derivative pendants was designed, synthesized and used to fabricate self-assembled copolymer nanoparticles in an aqueous condition. The hydrodynamic diameters of the multifunctional copolymer P1-o nanoparticles reversibly switched between two stable states with two stimuli: light and temperature in an aqueous suspension.Graphical abstract:
Diastereomer discrimination was observed in the formation of a metallomacrocycle from a racemic l... more Diastereomer discrimination was observed in the formation of a metallomacrocycle from a racemic ligand based on Tro¨ger's base. The metallomacrocycle exhibited a dramatic increase in fluorescence intensity compared to the ligand and its fluorescence was efficiently quenched by C 60 .
The addition of molecular switching elements into conjugated polymers would provide a means to mo... more The addition of molecular switching elements into conjugated polymers would provide a means to modulate the optoelectronic properties these versatile materials offer to molecular electronic, 1 sensing, 2 and logic 3 technologies. Photoresponsive molecular systems based on the dithienylethene (DTE) architecture are particularly suitable choices as "on/off" modulators of conjugation due to their undergoing reversible ring-closing reactions between two isomers, each having markedly different optical and electronic properties. 4 Despite efforts directed toward developing conjugated materials from DTEs, 5 systems that incorporate multiple chromophores into a single conjugated backbone while retaining the photoswitching behavior of all components have been elusive. The major problem is rapid energy transfer (ET) from the singlet excited state of a ringopen isomer to an adjacent ring-closed DTE that takes precedence over photocyclization. The few examples that have multiple, adjacent DTEs undergoing photoinduced ring-closing tend to have more localized excited states and, therefore, properties similar to those of a single DTE unit. 6 Therefore, little benefit has been gained from integrating multiple DTEs into a single polymer, and nontraditional approaches to photochromic switching must be exercised to eliminate this paradox.
Only one type of lanthanide-doped upconverting nanoparticle (UCNP) is needed to reversibly toggle... more Only one type of lanthanide-doped upconverting nanoparticle (UCNP) is needed to reversibly toggle photoresponsive organic compounds between their two unique optical, electronic, and structural states by modulating merely the intensity of the 980 nm excitation light. This reversible "remote-control" photoswitching employs an excitation wavelength not directly absorbed by the organic chromophores and takes advantage of the fact that designer core-shell-shell NaYF 4 nanoparticles containing Er 3+ /Yb 3+ and Tm 3+ /Yb 3+ ions doped into separate layers change the type of light they emit when the power density of the near-infrared light is increased or decreased. At high power densities, the dominant emissions are ultraviolet and are appropriate to drive the ring-closing, forward reactions of dithienylethene (DTE) photoswitches. The visible light generated from the same core-shell-shell UCNPs at low power densities triggers the reverse, ring-opening reactions and regenerates the original photoisomers. The "remote-control" photoswitching using NIR light is as equally effective as the direct switching with UV and visible light, albeit the reaction rates are slower. This technology offers a highly convenient and versatile method to spatially and temporally regulate photochemical reactions using a single light source and changing either its power or its focal point.
(a) Scheme illustrating the ring-opening and release reactions of bicyclic compound 2b as it is i... more (a) Scheme illustrating the ring-opening and release reactions of bicyclic compound 2b as it is irradiated with visible or NIR light. (b) Changes in the UV-vis absorption spectra (left) and cropped photographs (right) of an acrylate film (8 × 7 × 1 mm) containing 2b + NaYF 4 :ErYb as it is irradiated with 980 nm light. The stripe observed in the right panel corresponds to the direction of the beam of the 980 nm laser.
Journal of Controlled Release, 2015
Light is an excellent means to externally control the properties of materials and small molecules... more Light is an excellent means to externally control the properties of materials and small molecules for many applications. Light's ability to initiate chemistries largely independent of a material's local environment makes it particularly useful as a bio-orthogonal and on-demand trigger in living systems. Materials responsive to UV light are widely reported in the literature; however, UV light has substantial limitations for in vitro and in vivo applications. Many biological molecules absorb these energetic wavelengths directly, not only preventing substantial tissue penetration but also causing detrimental photochemical reactions. The more innocuous nature of long-wavelength light (>400nm) and its ability at longer wavelengths (600-950nm) to effectively penetrate tissues is ideal for biological applications. Multi-photon processes (e.g. two-photon excitation and upconversion) using longer wavelength light, often in the near-infrared (NIR) range, have been proposed as a means of avoiding the negative characteristics of UV light. However, high-power focused laser light and long irradiation times are often required to initiate photorelease using these inefficient non-linear optical methods, limiting their in vivo use in mammalian tissues where NIR light is readily scattered. The development of materials that efficiently convert a single photon of long-wavelength light to chemical change is a viable solution to achieve in vivo photorelease. However, to date only a few such materials have been reported. Here we review current technologies for photo-regulated release using photoactive organic materials that directly absorb visible and NIR light.
Chemical communications (Cambridge, England), Jan 25, 2015
Exposure to UV light generates a ring-closed isomer of a diarylethene, which undergoes very slow ... more Exposure to UV light generates a ring-closed isomer of a diarylethene, which undergoes very slow bond breaking and release even after the light is turned off. The rate of release is increased by exposing the isomer to UV and/or visible light.
Angewandte Chemie International Edition, 2010
We introduce a means of efficiently photo-uncaging active compounds from amino-1,4-benzoquinone i... more We introduce a means of efficiently photo-uncaging active compounds from amino-1,4-benzoquinone in aqueous environments. Aqueous photochemistry of this photocage with one-photon red light is typically not efficient unless the photocaged molecules are allowed to assemble into nanoparticles. A variety of biologically active molecules were functionalized with the photocage and subsequently formulated into water-dispersible nanoparticles. Red light irradiation through various mammalian tissues achieved efficient photo-uncaging. Co-encapsulation of NIR fluorescent dyes and subsequent photomodulation provides a NIR fluorescent tool to assess both particle location and successful photorelease.
Controlling chemistry in space and time has offered scientists and engineers powerful tools for r... more Controlling chemistry in space and time has offered scientists and engineers powerful tools for research and technology. For example, on-demand photo-triggered activation of neurotransmitters has revolutionized neuroscience. Non-invasive control of the availability of bioactive molecules in living organisms will undoubtedly lead to major advances; however, this requires the development of photosystems that efficiently respond to regions of the electromagnetic spectrum that innocuously penetrate tissue. To this end, we have developed a polymer that photochemically degrades upon absorption of one photon of visible light and demonstrated its potential for medical applications. Particles formulated from this polymer release molecular cargo in vitro and in vivo upon irradiation with blue visible light through a photoexpansile swelling mechanism.
Near-infrared (NIR) light-triggered release from polymeric capsules could make a major impact on ... more Near-infrared (NIR) light-triggered release from polymeric capsules could make a major impact on biological research by enabling remote and spatiotemporal control over the release of encapsulated cargo. The few existing mechanisms for NIR-triggered release have not been widely applied because they require custom synthesis of designer polymers, high-powered lasers to drive inefficient two-photon processes, and/or coencapsulation of bulky inorganic particles. In search of a simpler mechanism, we found that exposure to laser light resonant with the vibrational absorption of water (980 nm) in the NIR region can induce release of payloads encapsulated in particles made from inherently non-photo-responsive polymers. We hypothesize that confined water pockets present in hydrated polymer particles absorb electromagnetic energy and transfer it to the polymer matrix, inducing a thermal phase change. In this study, we show that this simple and highly universal strategy enables instantaneous and controlled release of payloads in aqueous environments as well as in living cells using both pulsed and continuous wavelength lasers without significant heating of the surrounding aqueous
solution.
Sun block for nanoparticles: Unintentional photorelease triggered by UV light is a problem in pho... more Sun block for nanoparticles: Unintentional photorelease triggered by UV light is a problem in photodynamic therapy. Encapsulating upconverting nanoparticles containing photoswitches in a UV-blocking amphiphilic polymer shuts down the one-photon process and only allows two-photon-driven photochemistry. Thus UV light is blocked while NIR light can reach the nanoparticle core and trigger photorelease.
One of the primary disadvantages of organic photochemistry is the need for high-energy UV light, ... more One of the primary disadvantages of organic photochemistry is the need for high-energy UV light, light that has many detrimental qualities. A viable solution to this problem is the use of upconverting nanoparticles (UCNP) that can locally convert near infrared (NIR) laser light into UV light or visible light of sufficient energy to drive organic photoreactions.
A novel amphiphilic photochromic copolymer P1-o consisting of a hydrophilic poly(N-isopropylacryl... more A novel amphiphilic photochromic copolymer P1-o consisting of a hydrophilic poly(N-isopropylacrylamide) backbone and thermally irreversible photochromic and hydrophobic 1,2-dithienylethene derivative pendants was designed, synthesized and used to fabricate self-assembled copolymer nanoparticles in an aqueous condition. The hydrodynamic diameters of the multifunctional copolymer P1-o nanoparticles reversibly switched between two stable states with two stimuli: light and temperature in an aqueous suspension.Graphical abstract:
Diastereomer discrimination was observed in the formation of a metallomacrocycle from a racemic l... more Diastereomer discrimination was observed in the formation of a metallomacrocycle from a racemic ligand based on Tro¨ger's base. The metallomacrocycle exhibited a dramatic increase in fluorescence intensity compared to the ligand and its fluorescence was efficiently quenched by C 60 .
The addition of molecular switching elements into conjugated polymers would provide a means to mo... more The addition of molecular switching elements into conjugated polymers would provide a means to modulate the optoelectronic properties these versatile materials offer to molecular electronic, 1 sensing, 2 and logic 3 technologies. Photoresponsive molecular systems based on the dithienylethene (DTE) architecture are particularly suitable choices as "on/off" modulators of conjugation due to their undergoing reversible ring-closing reactions between two isomers, each having markedly different optical and electronic properties. 4 Despite efforts directed toward developing conjugated materials from DTEs, 5 systems that incorporate multiple chromophores into a single conjugated backbone while retaining the photoswitching behavior of all components have been elusive. The major problem is rapid energy transfer (ET) from the singlet excited state of a ringopen isomer to an adjacent ring-closed DTE that takes precedence over photocyclization. The few examples that have multiple, adjacent DTEs undergoing photoinduced ring-closing tend to have more localized excited states and, therefore, properties similar to those of a single DTE unit. 6 Therefore, little benefit has been gained from integrating multiple DTEs into a single polymer, and nontraditional approaches to photochromic switching must be exercised to eliminate this paradox.
Only one type of lanthanide-doped upconverting nanoparticle (UCNP) is needed to reversibly toggle... more Only one type of lanthanide-doped upconverting nanoparticle (UCNP) is needed to reversibly toggle photoresponsive organic compounds between their two unique optical, electronic, and structural states by modulating merely the intensity of the 980 nm excitation light. This reversible "remote-control" photoswitching employs an excitation wavelength not directly absorbed by the organic chromophores and takes advantage of the fact that designer core-shell-shell NaYF 4 nanoparticles containing Er 3+ /Yb 3+ and Tm 3+ /Yb 3+ ions doped into separate layers change the type of light they emit when the power density of the near-infrared light is increased or decreased. At high power densities, the dominant emissions are ultraviolet and are appropriate to drive the ring-closing, forward reactions of dithienylethene (DTE) photoswitches. The visible light generated from the same core-shell-shell UCNPs at low power densities triggers the reverse, ring-opening reactions and regenerates the original photoisomers. The "remote-control" photoswitching using NIR light is as equally effective as the direct switching with UV and visible light, albeit the reaction rates are slower. This technology offers a highly convenient and versatile method to spatially and temporally regulate photochemical reactions using a single light source and changing either its power or its focal point.
(a) Scheme illustrating the ring-opening and release reactions of bicyclic compound 2b as it is i... more (a) Scheme illustrating the ring-opening and release reactions of bicyclic compound 2b as it is irradiated with visible or NIR light. (b) Changes in the UV-vis absorption spectra (left) and cropped photographs (right) of an acrylate film (8 × 7 × 1 mm) containing 2b + NaYF 4 :ErYb as it is irradiated with 980 nm light. The stripe observed in the right panel corresponds to the direction of the beam of the 980 nm laser.