Abstract:Nanocapsules present a promising platform for delivering chemicals and biomolecules to a site of action in a living organism. Because the biological action of the encapsulated molecules is blocked until they are released from the nanocapsules, the encapsulation structure enables triggering of the topical and timely action of the molecules at the target site. A similar mechanism seems promising for the spatiotemporal control of signal transduction triggered by the release of signal molecules in neuronal, metabo… Show more
“…These sensitivity values are significantly higher than that of conventional thermosensitive fluorescent nanoprobes. It has been demonstrated that the phase transition temperature of a fully hydrated membrane of saturated diacyl phosphocholine (PC) linearly correlates with the reciprocal of hydrocarbon chain length 24,29 . Thereby, the fluorescence switching temperature of PC-NVSQ can be readily tuned by changing the phase transition temperature, which is determined by the host lipid membrane.…”
Section: Resultsmentioning
confidence: 99%
“…Our current study has achieved the sensing and imaging of threshold temperatures corresponding to phase transitions of nanovesicles. By using these fluorescent nanoprobes, for example, monitoring the threshold temperature and controlling the temperature range at the nano- and microscale for heat-triggered drug release from the nanovesicles 26,28,29 , digital polymerase chain reaction in microdroplets 52 and protein expression in artificial cells or protocells 53 become possible.Figure 8Proposed mechanism for SQR22 fluorescence switching in the lipid bilayer membrane as a response to phase transition. The fluorescence off/on switching is a result of the reversible aggregation-caused quenching/disaggregation-induced emission of SQR22 in the gel to liquid crystalline phase transition temperature ( T ) of the lipid bilayer membrane.…”
Section: Resultsmentioning
confidence: 99%
“…A typical thermal characteristic of these NV is the reversible phase transition at a specific temperature, called phase transition temperature 24 . Since the molecular packing state and the permeability of the lipid bilayer membrane cooperatively changes at the phase transition temperature, the phase transition of the lipid bilayer membrane is used for the release of the encapsulated cargo from the NV at a threshold temperature 25–29 . From the aspects of temperature sensing and imaging, the cooperative switching of fluorescence quenching and emission at the phase transition temperature of NV is an attractive methodology for sensing and imaging of threshold temperature, which can be tuned according to the phase transition temperature of the NV.…”
Thermosensitive fluorescent dyes can convert thermal signals into optical signals as a molecular nanoprobe. These nanoprobes are playing an increasingly important part in optical temperature sensing and imaging at the nano- and microscale. However, the ability of a fluorescent dye itself has sensitivity and accuracy limitations. Here we present a molecular strategy based on self-assembly to overcome such limitations. We found that thermosensitive nanovesicles composed of lipids and a unique fluorescent dye exhibit fluorescence switching characteristics at a threshold temperature. The switch is rapid and reversible and has a high signal to background ratio (>60), and is also highly sensitive to temperature (10–22%/°C) around the threshold value. Furthermore, the threshold temperature at which fluorescence switching is induced, can be tuned according to the phase transition temperature of the lipid bilayer membrane forming the nanovesicles. Spectroscopic analysis indicated that the fluorescence switching is induced by the aggregation-caused quenching and disaggregation-induced emission of the fluorescent dye in a cooperative response to the thermotropic phase transition of the membrane. This mechanism presents a useful approach for chemical and material design to develop fluorescent nanomaterials with superior fluorescence sensitivity to thermal signals for optical temperature sensing and imaging at the nano- and microscales.
“…These sensitivity values are significantly higher than that of conventional thermosensitive fluorescent nanoprobes. It has been demonstrated that the phase transition temperature of a fully hydrated membrane of saturated diacyl phosphocholine (PC) linearly correlates with the reciprocal of hydrocarbon chain length 24,29 . Thereby, the fluorescence switching temperature of PC-NVSQ can be readily tuned by changing the phase transition temperature, which is determined by the host lipid membrane.…”
Section: Resultsmentioning
confidence: 99%
“…Our current study has achieved the sensing and imaging of threshold temperatures corresponding to phase transitions of nanovesicles. By using these fluorescent nanoprobes, for example, monitoring the threshold temperature and controlling the temperature range at the nano- and microscale for heat-triggered drug release from the nanovesicles 26,28,29 , digital polymerase chain reaction in microdroplets 52 and protein expression in artificial cells or protocells 53 become possible.Figure 8Proposed mechanism for SQR22 fluorescence switching in the lipid bilayer membrane as a response to phase transition. The fluorescence off/on switching is a result of the reversible aggregation-caused quenching/disaggregation-induced emission of SQR22 in the gel to liquid crystalline phase transition temperature ( T ) of the lipid bilayer membrane.…”
Section: Resultsmentioning
confidence: 99%
“…A typical thermal characteristic of these NV is the reversible phase transition at a specific temperature, called phase transition temperature 24 . Since the molecular packing state and the permeability of the lipid bilayer membrane cooperatively changes at the phase transition temperature, the phase transition of the lipid bilayer membrane is used for the release of the encapsulated cargo from the NV at a threshold temperature 25–29 . From the aspects of temperature sensing and imaging, the cooperative switching of fluorescence quenching and emission at the phase transition temperature of NV is an attractive methodology for sensing and imaging of threshold temperature, which can be tuned according to the phase transition temperature of the NV.…”
Thermosensitive fluorescent dyes can convert thermal signals into optical signals as a molecular nanoprobe. These nanoprobes are playing an increasingly important part in optical temperature sensing and imaging at the nano- and microscale. However, the ability of a fluorescent dye itself has sensitivity and accuracy limitations. Here we present a molecular strategy based on self-assembly to overcome such limitations. We found that thermosensitive nanovesicles composed of lipids and a unique fluorescent dye exhibit fluorescence switching characteristics at a threshold temperature. The switch is rapid and reversible and has a high signal to background ratio (>60), and is also highly sensitive to temperature (10–22%/°C) around the threshold value. Furthermore, the threshold temperature at which fluorescence switching is induced, can be tuned according to the phase transition temperature of the lipid bilayer membrane forming the nanovesicles. Spectroscopic analysis indicated that the fluorescence switching is induced by the aggregation-caused quenching and disaggregation-induced emission of the fluorescent dye in a cooperative response to the thermotropic phase transition of the membrane. This mechanism presents a useful approach for chemical and material design to develop fluorescent nanomaterials with superior fluorescence sensitivity to thermal signals for optical temperature sensing and imaging at the nano- and microscales.
“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Hierarchical core-shell nanocapsules are promising carriers that could encapsulate various oil actives in a polymer shell, protect them from harsh ambient conditions and release them when it is required. [14][15][16][17][18][19] Encapsulation of the oil actives in the nanocapsules can effectively alleviate their deficiencies of low stability and poor dispersity in water, thus increasing their bioavailability. [20] For example, many food active molecules, such as antioxidants and aromas, exist in an oil form and effective encapsulation of the oils in the core of nanocapsules is generally required for practical applications.…”
Co-precipitation is generally referred to the co-precipitation of two solids and is widely used to prepare active-loaded nanoparticles. Here, we demonstrate that liquid and solid could precipitate simultaneously to produce hierarchical core-shell nanocapsules that encapsulate an oil core in a polymer shell. During the co-precipitation process, the polymer preferentially deposits at the oil/water interface, wetting both the oil and water phases; the behavior is determined by the spreading coefficients and driven by the energy minimization. The technique is applicable to directly encapsulate various oil actives and avoid the use of toxic solvent or surfactant during the preparation process. The obtained core-shell nanocapsules harness the advantage of biocompatibility, precise control over the shell thickness, high loading capacity, high encapsulation efficiency, good dispersity in water and improved stability against oxidation. The applications of the nanocapsules as delivery vehicles are demonstrated by the excellent performances of natural colorant and anti-cancer drug-loaded nanocapsules. The core-shell nanocapsules with a controlled hierarchical structure are, therefore, ideal carriers for practical applications in food, cosmetic and drug delivery.Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff)) Published online: ((will be filled in by the editorial staff)) nanocapsules (blue columns), suggesting that the nanocapsules are biocompatible and are ideal carriers for anti-cancer drugs.Hierarchical core-shell nanocapsules are developed by controlled co-precipitation and phase separation. The core-shell nanocapsules serve as excellent delivery vehicles and possess tunable shell thickness, high encapsulation efficiency, high loading capacity, good dispersity in water, improved stability and pH-triggered release, which opens a door to a range of new applications in food, cosmetic and drug delivery.
“…Neurotransmitters are π-donor biomolecules that play a pivotal role in communication between cells through signal transduction in living organisms [ 35 ]. Generally, an imbalance of these neurotransmitter levels could cause psychiatric and neurological disorders such as: depression, schizophrenia, Parkinson’s and Alzheimer’s diseases [ 36 ].…”
Bipyridinium salts, commonly known as viologens, are π-acceptor molecules that strongly interact with π-donor compounds, such as porphyrins or amino acids, leading their self-assembling. These properties have promoted us to functionalize polysilicon microparticles with bipyridinium salts for the encapsulation and release of π-donor compounds such as catecholamines and indolamines. In this work, the synthesis and characterization of four gemini-type amphiphilic bipyridinium salts (1·4PF6–4·4PF6), and their immobilization either non-covalently or covalently on polysilicon surfaces and microparticles have been achieved. More importantly, they act as hosts for the subsequent incorporation of π-donor neurotransmitters such as dopamine, serotonin, adrenaline or noradrenaline. Ultraviolet-visible absorption and fluorescence spectroscopies and high-performance liquid chromatography were used to detect the formation of the complex in solution. The immobilization of bipyridinium salts and neurotransmitter incorporation on polysilicon surfaces was corroborated by contact angle measurements. The reduction in the bipyridinium moiety and the subsequent release of the neurotransmitter was achieved using ascorbic acid, or Vitamin C, as a triggering agent. Quantification of neurotransmitter encapsulated and released from the microparticles was performed using high-performance liquid chromatography. The cytotoxicity and genotoxicity studies of the bipyridinium salt 1·4PF6, which was selected for the non-covalent functionalization of the microparticles, demonstrated its low toxicity in the mouse fibroblast cell line (3T3/NIH), the human liver carcinoma cell line (HepG2) and the human epithelial colorectal adenocarcinoma cell line (Caco-2).
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