Biowaste treatment by black soldier fly larvae (BSFL, Hermetia illucens) has received global research interest and growing industrial application. Larvae farming conditions, such as temperature, pH, and moisture, have been critically examined. However, the substrate carbon to nitrogen ratio (C/N), one of the key parameters that may affect larval survival and bioconversion efficiency, is significantly less studied. The current study aimed to compare the nitrogen supplying effects of 9 nitrogen species (i.e., NH₄Cl, NaNO₃, urea, uric acid, Gly, L-Glu, L-Glu:L-Asp (1:1, w/w), soybean flour, and fish meal) during food waste larval treatment, and further examine the C/N effects on the larval development and bioconversion process, using the C/N adjustment with urea from the initial 21:1 to 18:1, 16:1, 14:1, 12:1, and 10:1, respectively. The food wastes were supplied with the same amount of nitrogen element (1 g N/100 g dry wt) in the nitrogen source trial and different amount of urea in the C/N adjustment trial following larvae treatment. The results showed that NH₄Cl and NaNO₃ caused significant harmful impacts on the larval survival and bioconversion process, while the 7 organic nitrogen species resulted in no significant negative effect. Further adjustment of C/N with urea showed that the C/N range between 18:1 and 14:1 was optimal for a high waste reduction performance (73.5–84.8%, p < 0.001) and a high larvae yield (25.3–26.6%, p = 0.015), while the C/N range of 18:1 to 16:1 was further optimal for an efficient larval protein yield (10.1–11.1%, p = 0.003) and lipid yield (7.6–8.1%, p = 0.002). The adjustment of C/N influenced the activity of antioxidant enzymes, such as superoxide dismutase (SOD, p = 0.015), whereas exerted no obvious impact on the larval amino acid composition. Altogether, organic nitrogen is more suitable than NH₄Cl and NaNO₃ as the nitrogen amendment during larval food waste treatment, addition of small amounts of urea, targeting C/N of 18:1–14:1, would improve the waste reduction performance, and application of C/N at 18:1–16:1 would facilitate the larval protein and lipid bioconversion process.

Piperlongumine, a natural alkaloid substance extracted from the fruit of the long pepper (Piper longum Linn.), is known to inhibit the cytosolic thioredoxin reductase (TXNRD1 or TrxR1) and selectively kill cancer cells. However, the details and mechanism of the inhibition by piperlongumine against TXNRD1 remain unclear. In this study, based on the classical DTNB reducing assay, irreversible inhibition of recombinant TXNRD1 by piperlongumine was found and showed an apparent k_inact value of 0.206 × 10⁻³ µM⁻¹ min⁻¹. Meanwhile, compared with the wild-type TXNRD1 (-GCUG), the UGA-truncated form (-GC) of TXNRD1 was resistant to piperlongumine, suggesting the preferential target of piperlongumine is the selenol (-SeH) at the C-terminal redox motif of the enzyme. Interestingly, the high concentration of piperlongumine-inhibited TXNRD1 showed that its Sec-dependent activity is decayed but its intrinsic NADPH oxidase activity is retained. Furthermore, piperlongumine did not induce ferroptosis in HCT116 cells at 10 µM, whereas significantly promoted erastin-induced lipid oxidation, which could be alleviated by supplying glutathione (GSH) or N-acetyl L-cysteine (NAC). However, restricting GSH synthesis by inhibiting glutaminase (GLS) using the small molecule inhibitor CB-839 only slightly enhanced erastin-induced cell death. Taken together, this study elucidates the molecular mechanism of the antitumor capacity of piperlongumine by targeting TXNRD1 and reveals the potential possibility of inhibiting TXNRD1 to strengthen cancer cells’ ferroptosis.

Tissue engineering scaffolds provide biological and physiochemical cures to guide tissue recovery, and electrical signals through the electroactive materials possess tremendous potential to modulate the cell fate. In this study, a novel electroactive hydrogel scaffold was fabricated by assembling poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles on a carboxymethyl chitosan/gelatin (CMCS/Gel) composite hydrogel surface via in situ chemical polymerization. The chemical structure, morphology, conductivity, porosity, swelling rate, in vitro biodegradation, and mechanical properties of the prepared hydrogel samples were characterized. The adhesion, proliferation, and differentiation of neural stem cells (NSCs) on conductive hydrogels were investigated. The CMCS/Gel-PEDOT hydrogels exhibited high porosity, excellent water absorption, improved thermal stability, and adequate biodegradability. Importantly, the mechanical properties of the prepared hydrogels were similar to those of brain tissue, with electrical conductivity up to (1.52 ± 0.15) × 10⁻³ S/cm. Compared to the CMCS/Gel hydrogel, the incorporation of PEDOT nanoparticles significantly improved the adhesion of NSCs, and supported long-term cell growth and proliferation in a three-dimensional (3D) microenvironment. In addition, under the differentiation condition, the conductive hydrogel also significantly enhanced neuronal differentiation with the up-regulation of β-tubulin III expression. These results suggest that CMCS/Gel-PEDOT hydrogels may be an attractive conductive substrate for further studies on neural tissue repair and regeneration.