3 research outputs found
Data_Sheet_1_Nisin and ε-polylysine combined treatment enhances quality of fresh-cut jackfruit at refrigerated storage.docx
This study investigated the effects of nisin combined with ε-polylysine on microorganisms and the refrigerated quality of fresh-cut jackfruit. After being treated with distilled water (control), nisin (0.5 g/L), ε-polylysine (0.5 g/L), and the combination of nisin (0.1 g/L) and ε-polylysine (0.4 g/L), microporous modified atmosphere packaging (MMAP) was carried out and stored at 10 ± 1°C for 8 days. The microorganisms and physicochemical indexes were measured every 2 days during storage. The results indicated that combined treatment (0.1 g/L nisin, 0.4 g/L ε-polylysine) had the best preservation on fresh-cut jackfruit. Compared with the control, combined treatment inhibited microbial growth (total bacterial count, mold and yeast), reduced the weight loss rate, respiratory intensity, polyphenol oxidase and peroxidase activities, and maintained higher sugar acid content, firmness, and color. Furthermore, it preserved higher levels of antioxidant compounds, reduced the accumulation of malondialdehyde and hydrogen peroxide, thereby reducing oxidative damage and maintaining high nutritional and sensory qualities. As a safe application of natural preservatives, nisin combined with ε-polylysine treatment has great application potential in the fresh-cut jackfruit industry.</p
Alleviating the Liver Toxicity of Chemotherapy via pH-Responsive Hepatoprotective Prodrug Micelles
Nanocarriers have
been extensively utilized to enhance the anti-tumor performance of
chemotherapy, but it is very challenging to eliminate the associated
hepatotoxicity. This was due to the significant liver accumulation
of cytotoxic drug-loaded nanocarriers as a consequence of systemic
biodistribution. To address this, we report a novel type of nanocarrier
that was made of hepatoprotective compound (oleanolic acid/OA) with
a model drug (methotrexate/MTX) being physically encapsulated. OA
was covalently connected with methoxy polyÂ(ethylene glycol) (mPEG)
via a hydrazone linker, generating amphiphilic mPEG–OA prodrug
conjugate that could self-assemble into pH-responsive micelles (ca.
100 nm), wherein the MTX loading was ca. 5.1% (w/w). The micelles
were stable at pH 7.4 with a critical micelle concentration of 10.5
μM. At the acidic endosome/lysosome microenvironment, the breakdown
of hydrazone induced the micelle collapse and fast release of payloads
(OA and MTX). OA also showed adjunctive anti-tumor effect with a low
potency, which was proved in 4T1 cells. In the mouse 4T1 breasttumor
model, MTX-loaded mPEG–OA micelles demonstrated superior capability
regarding in vivo tumorgrowth inhibition because of the passive tumor
targeting of nanocarriers. Unsurprisingly, MTX induced significant
liver toxicity, which was evidenced by the increased liver mass and
increased levels of alanine transaminase, aspartate transaminase,
and lactate dehydrogenase in serum as well as in liver homogenate.
MTX-induced hepatotoxicity was also accompanied with augmented oxidative
stress, for example, the increase of the malondialdehyde level and
the reduction of glutathione peroxidase and superoxide dismutase concentration
in the liver. As expected, mPEG–OA micelles significantly reduced
the liver toxicity induced by MTX because of the hepatoprotective
action of OA, which was supported by the reversal of all the above
biomarkers and qualitative histological analysis of liver tissue.
This work offers an efficient approach for reducing the liver toxicity
associated with chemotherapy, which can be applied to various antitumor
drugs and hepatoprotective materials
Multifunctional Micelles Dually Responsive to Hypoxia and Singlet Oxygen: Enhanced Photodynamic Therapy via Interactively Triggered Photosensitizer Delivery
Nanoparticulate antitumor
photodynamic therapy (PDT) has been suffering from the limited dose
accumulation in tumor. Herein, we report dually hypoxia- and singlet
oxygen-responsive polymeric micelles to efficiently utilize the photosensitizer
deposited in the disease site and hence facilely improve PDT’s
antitumor efficacy. Tailored methoxy polyÂ(ethylene glycol)-azobenzene-polyÂ(aspartic
acid) copolymer conjugate with imidazole as the side chains was synthesized.
The conjugate micelles (189 ± 19 nm) obtained by self-assembly
could efficiently load a model photosensitizer, chlorin e6 (Ce6) with
a loading of 4.1 ± 0.5% (w/w). The facilitated cellular uptake
of micelles was achieved by the triggered azobenzene collapse that
provoked polyÂ(ethylene glycol) shedding; rapid Ce6 release was enabled
by imidazole oxidation that induced micelle disassembly. In addition,
the singlet oxygen-mediated cargo release not only addressed the limited
diffusion range and short half-life of singlet oxygen but also decreased
the oxygen level, which could in turn enhance internalization and
increase the intracellular Ce6 concentration. The hypoxia-induced
dePEGylation and singlet oxygen-triggered Ce6 release was demonstrated
both in aqueous buffer and in Lewis lung carcinoma (LLC) cells. The
cellular uptake study demonstrated that the dually responsive micelles
could deliver significantly more Ce6 to the cells, which resulted
in a substantially improved cytotoxicity. This concurred well with
the superior in vivo antitumor ability of micelles in a LLC tumor-bearing
mouse model. This study presented an intriguing nanoplatform to realize
interactively triggered photosensitizer delivery and improved antitumor
PDT efficacy