Dataset Information

Temperature-Controlled Conversion of Boc-Protected Methylene Blue: Advancing Solid-State Time-Temperature Indicators.

ABSTRACT: Cold-chain management is of high importance in preserving perishable products and in retaining quality. A visible marker on packages indicating complete maintenance of the cold chain assures safe consumption of products by end-users and assists in reducing waste. Time-temperature indicators (TTIs) are integrated markers that provide information about exposure of packages to adverse temperature and have been gaining increased attention by consumers. Here we present a methylene-blue-based derivative, N,N,N',N'-tetramethyl-N¹⁰ -Boc-phenothiazine-3,7-diamine (BocPTDA), that can be used as a solid-state organic TTI dye, exhibiting an irreversible change from colorless to blue green upon heating. The conversion properties, studied using a silicagel-coated plate, confirmed that BocPTDA undergoes a color change above 20 °C. At temperatures of 4 °C and below, no visible changes are exhibited, making BocPTDA a well-suited marker for monitoring abrupt temperature deviations indicating improper cold-chain management. Thus, application of BocPTDA-based TTI systems on packages could inform consumers about the cold-chain maintenance, assuring quality and safe consumption.

SUBMITTER: Merkes JM

PROVIDER: S-EPMC8576189 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature

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Temperature-Controlled Conversion of Boc-Protected Methylene Blue: Advancing Solid-State Time-Temperature Indicators.

Merkes Jean Michel JM Banala Srinivas S

ChemistryOpen 20211101 11

Cold-chain management is of high importance in preserving perishable products and in retaining quality. A visible marker on packages indicating complete maintenance of the cold chain assures safe consumption of products by end-users and assists in reducing waste. Time-temperature indicators (TTIs) are integrated markers that provide information about exposure of packages to adverse temperature and have been gaining increased attention by consumers. Here we present a methylene-blue-based derivati ...[more]

PMID: 34750993

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Project description:This work reports the synthesis of nanosilica-coated magnetic carbonaceous adsorbents (MCA@SiO2) using low-temperature hydrothermal carbonization technique (HCT) and the feasibility to utilize it for methylene blue (MB) adsorption. Initially, a carbon precursor (CP) was synthesized from corn starch under saline conditions at 453 K via HCT followed by the magnetization of CP again via HCT at 453 K. Subsequently, MCA was coated with silica nanoparticles. MCA and MCA@SiO2 were characterized using X-ray diffraction, Fourier transform infrared, scanning electron microscopy/energy-dispersive spectroscopy, transmission electron microscopy, and Brunauer-Emmett-Teller (BET) N2 adsorption-desorption isotherms. The BET surface area of MCA and MCA@SiO2 were found to be 118 and 276 m2 g-1, respectively. Adsorption of MB onto MCA@SiO2 was performed using batch adsorption studies and in the optimum condition, MCA@SiO2 showed 99% adsorption efficiency with 0.5 g L-1 of MCA@SiO2 at pH 7. Adsorption isotherm studies predicted that MB adsorption onto MCA@SiO2 was homogeneous monolayer adsorption, which was best described using a Langmuir model with the maximum adsorption capacity of 516.9 mg g-1 at 25 °C. During adsorption kinetics, a rapid dye removal was observed which followed pseudo-first- as well as pseudo-second-order models, which suggested that MB dye molecules were adsorbed onto MCA@SiO2 via both ion exchange as well as the chemisorption process. The endothermic and spontaneous nature of the adsorption of MB onto MCA@SiO2 was established by thermodynamics studies. Mechanism of dye diffusion was collectively governed by intraparticle diffusion and film diffusion processes. Furthermore, MB was also selectively adsorbed from its mixture with an anionic dye, that is, methyl orange. Column adsorption studies showed that approximately 500 mL of MB having 50 mg L-1 concentration can be treated with 0.5 g L-1 of MCA@SiO2. Furthermore, MCA@SiO2 was repeatedly used for 20 cycles of adsorption-desorption of MB. Therefore, MCA@SiO2 can be effectively utilized in cationic dye-contaminated wastewater remediation applications.

Project description:A promising alternative to antibiotics for treatment of Staphylococcus aureus infections is photodynamic inactivation (PDI), which employs a photosensitizer (PS) that produces cytotoxic reactive oxygen species (ROS) when exposed to molecular oxygen and antimicrobial blue light in the spectrum of 400-470 nm. Although the precise mechanistic basis of PDI has not been defined, the formation of ROS and free radicals that oxidize a number of cellular targets, including membrane lipids, damage to proteins and nucleic acids result in inactivation of essential cellular functions and subsequent cell death. Because PDI is non-selective and affects multiple cellular targets, development of resistance or tolerance to PDI has been considered to be unlikely and attempts to induce S. aureus resistance or tolerance upon repeated sub-lethal doses of PDI have not succeeded. However, multiple aspects of PDI suggest that development of tolerance is highly probable, in particular when PDI is used for treatment of infections where the environment at the infection site prevents penetration of PDI at a level sufficient to cause death of all bacteria and with tolerant phenotypes emerging from the surviving bacteria. In this study, we sought to identify the mechanisms that contribute to PDI tolerance in S. aureus. S. aureus HG003 and the isogenic HG003DmutSL strain with defects in DNA mismatch repair were used to evaluate the response of S. aureus and the roles of DNA mismatch repair and gene regulatory networks to repeated sublethal doses of PDI. Global transcriptome and genome analyses were used in an agnostic approach to identify the underlying transcriptional responses and genetic adaptations that occur as a result of repeated PDI and contribute to PDI tolerance. Our results reveal multiple metabolic, transport and cell wall biogenesis pathways that contribute to PDI tolerance, and a S. aureus regulatory gene likely responsible for the adaptive transcriptional response to PDI.

Dataset Information

Temperature-Controlled Conversion of Boc-Protected Methylene Blue: Advancing Solid-State Time-Temperature Indicators.

Publications

Temperature-Controlled Conversion of Boc-Protected Methylene Blue: Advancing Solid-State Time-Temperature Indicators.

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