Chemo-photodynamic antitumour therapy based on Er-doped upconversion nanoparticles coated with hypocrellin B and MnO2.

An antitumour chemo-photodynamic therapy nanoplatform was constructed based on phospholipid-coated NaYF4: Yb/Er upconversion nanoparticles (UCNPs). In this work, the amphiphilic block copolymer DSPE-PEG2000 was combined with the surface ligand oleic acid of the UCNPs through hydrophobic interaction to form liposomes with a dense hydrophobic layer in which the photosensitizer hypocrellin B (HB) was assembled. The coated HB formed J-aggregates, which caused a large redshift in the absorption spectrum and improved the quantum efficiency of energy transfer. Furthermore, MnO2 nanosheets grew in-situ on the liposomes through OMn coordination. Therefore, a multifunctional tumour microenvironment (TME)-responsive theranostic nanoplatform integrating photodynamic therapy (PDT) and chemodynamic therapy (CDT) was successfully developed. The results showed that this NIR-mediated chemo-photodynamic therapy nanoplatform was highly efficient for oncotherapy.

Natural Wood-Derived Macroporous Cellulose for Highly Efficient and Ultrafast Elimination of Double-Stranded RNA from In Vitro-Transcribed mRNA.

Double-stranded RNA (dsRNA) is a major impurity that can induce innate immune responses and cause adverse drug reactions. Removing dsRNA is an essential and non-trivial process in manufacturing mRNA. Current methods for dsRNA elimination use either high-performance liquid chromatography or microcrystalline cellulose, rendering the process complex, expensive, toxic, and/or time-consuming. This study introduces a highly efficient and ultrafast method for dsRNA elimination using natural wood-derived macroporous cellulose (WMC). With a naturally formed large total pore area and low tortuosity, WMC removes up to 98% dsRNA within 5 min. This significantly shortens the time for mRNA purification and improves purification efficiency. WMC can also be filled into chromatographic columns of different sizes and integrates with fast-protein liquid chromatography for large-scale mRNA purification to meet the requirements of mRNA manufacture. This study further shows that WMC purification improves the enhanced green fluorescent protein mRNA expression efficiency by over 28% and significantly reduces cytokine secretion and innate immune responses in the cells. Successfully applying WMC provides an ultrafast and efficient platform for mRNA purification, enabling large-scale production with significant cost reduction.

Lateral flow immunoassay for rapid and sensitive detection of dsRNA contaminants in in vitro-transcribed mRNA products.

High purity is essential in mRNA-based therapeutic applications. A major contaminant of in vitro-transcribed (IVT) mRNA manufacturing is double-stranded RNA (dsRNA), which can induce severe anti-viral immune responses. Detection methods, such as agarose gel electrophoresis, ELISA, and dot-blot assay, are used to detect the existence of dsRNA in IVT mRNA products. However, these methods are either not sensitive enough or time-consuming. To overcome these challenges, we develop a rapid, sensitive, and easy-to-implement colloidal gold nanoparticle-based lateral flow strip assay (LFSA) with sandwich format for the detection of dsRNA from IVT process. dsRNA contaminant can be determined visually on the test strip or quantitatively with a portable optical detector. This method allows for a 15 min detection of N1-methyl-pseudouridine (m1Ψ)-containing dsRNA with a detection limit of 69.32 ng/mL. Furthermore, we establish the correlation between the LFSA test results and the immune response caused by dsRNA in mice. The LFSA platform allows the rapid, sensitive, and quantitative monitoring of purity in massive IVT mRNA products and aids for the prevention of immunogenicity by dsRNA impurities.

Paper-based LRET sensor for the detection of total heavy rare-earth ions.

Based on the mechanism of luminescence resonance energy transfer (LRET) and using a special single strand DNA as the recognition element, a portable paper-based sensor for the accurate detection of total heavy rare-earth ions (mainly Gd3+, Tb3+ and Dy3+) concentration was proposed. The RNA cleaving-DNAzyme should recognize rare-earth ions to cleave RNA on DNA duplexes linking UCNPs and AuNPs, causing UCNPs and AuNPs to approach each other, inducing LRET, which attenuated the green upconversion luminescence (UCL) triggered by the 980 nm laser. UCL was captured by a charge-coupled device (CCD) image sensor and processed with the red-green-blue (RGB) image to quantitatively analyze heavy rare-earth ions in the samples. In the range of 5-50 µmol·L-1, the sensor has good sensitivity, with the limit of detection of 1.26 µmol L-1.

Detection of phospholipase A2 in serum based on LRET mechanism between upconversion nanoparticles and SYBR green I.

Phospholipase A2 (PLA2) may be a vital biomarker for the prediction and diagnosis of some diseases. Consequently, it is of great significance to quantitatively detect PLA2 in biologic samples. Herein, on the basis of the principle of luminescence resonance energy transfer (LRET) between upconversion nanoparticles (UCNPs) and SYBR Green I (SG), we proposed a technology for the highly sensitive detection of PLA2 amount. Therein, as an energy receptor, SG will be quantitatively loaded into liposomes firstly. Then, due to the hydrolysis of liposomes under the catalysis of PLA2, SG will be released and inserted into the double-stranded DNA (dsDNA) on the surface of UCNPs, which triggers the LRET because of the shortening of effective spatial distance between UCNPs and SG. Under exciting of NIR light, UCNPs emit luminescence at 476 nm, which makes SG emit fluorescence at 522 nm through LRET. Under optimal conditions, the emission intensity ratio (I522 nm/I476 nm) increased linearly with the PLA2 amount in the range of 20 U/L to 400 U/L, and the limit of detection (LOD) reached 15 U/L. Here, after comparing with the clinical standard method, it is found that the biosensor is expected to provide a convenient and sensitive assay for the detection of PLA2 in actual serum samples. Furthermore, such biosensor can also be used to test the inhibitor of PLA2.

Controllable Synthesis and Biological Application of Schiff Bases from d-Glucosamine and Terephthalaldehyde.

Theoretically, the two aldehydes of terephthalaldehyde (TPA) are equivalent, so the single or double Schiff base from TPA and d-glucosamine (Glc) may be formed at the same time. However, it is preferred to produce separately a single Schiff base (L1 ) or double Schiff base (L2 ) for different synthesis systems of anhydrous methanol or water-methanol. We calculated the Δr G of the formation of compounds L1 and L2 by density functional theory (DFT). In an anhydrous methanol system, the Δr G values of L1 and L2 are both below zero and L2 is lower, suggesting the spontaneous formation of the two Schiff bases. Though adjusting the molar ratio of Glc to TPA, L1 and L 2 both were separately formed in anhydrous methanol. However, in the water-methanol system, L2 was absent, which is most likely due to higher Δr G (4.95 eV) and better water solubility. The results also exhibits that the positive charge of C in -CHO for TPA is smaller in a mixed solvent than that in methanol, which confirms that the nucleophilic reaction of the Schiff base is more difficult in a mixed solvent. Therefore, we could realize to control the synthesis of a pure single or double Schiff base from Glc and TPA by adjusting the molar ratio and solvent. The as-prepared two kinds of Schiff bases have strong optical properties, high bacteriostatic activity, and can be used as fluorescent probes for tumor cell imaging.