Rational Design of Short Peptide-Based Hydrogels with MMP‑2 Responsiveness for Controlled Anticancer Peptide Delivery

Molecular self-assembly makes it feasible to harness the structures and properties of advanced materials via initial molecular design. To develop short peptide-based hydrogels with stimuli responsiveness, we designed here short amphiphilic peptides by engineering protease cleavage site motifs into self-assembling peptide sequences. We demonstrated that the designed Ac-I₃SLKG-NH₂ and Ac-I₃SLGK-NH₂ self-assembled into fibrillar hydrogels and that the Ac-I₃SLKG-NH₂ hydrogel showed degradation in response to MMP-2 but the Ac-I₃SLGK-NH₂ hydrogel did not. The cleavage of Ac-I₃SLKG-NH₂ into Ac-I₃S and LKG-NH₂ was found to be mechanistically responsible for the enzymatic degradation. Finally, when an anticancer peptide G­(IIKK)₃I-NH₂ (G3) was entrapped into Ac-I₃SLKG-NH₂ hydrogels, its release was revealed to occur in a “cell-demanded” way in the presence of HeLa cells that overexpress MMP-2, therefore leading to a marked inhibitory effect on their growth on the gels

Nonaqueous Lyotropic Liquid-Crystalline Phases Formed by Gemini Surfactants in a Protic Ionic Liquid

The aggregation behaviors of three Gemini surfactants [(C_<i>s</i>H_2<i>s</i>-α,ω-(Me₂N⁺C_<i>m</i>H_2<i>m</i>+1Br^–)₂, <i>s</i> = 2, <i>m</i> = 10, 12, 14] in a protic ionic liquid, ethylammonium nitrate (EAN), have been investigated. The polarized optical microscopy and small-angle X-ray scattering (SAXS) measurements are used to explore the lyotropic liquid crystal (LLC) formation. Compared to the LLCs formed in aqueous environment, the normal hexagonal and lamellar phases disappear. However, with increasing the surfactant concentration, a new reverse hexagonal phase (H_II) can be mapped over a large temperature range except for other ordered aggregates including the isotropic solution phase and a two-phase coexistence region. The structural parameters of the H_II are calculated from the corresponding SAXS patterns, showing the influence of surfactant amount, alkyl chain length, and temperature. Meanwhile, the rheological profiles indicate a typical Maxwell behavior of the LLC phases formed in EAN

Presentation_1_Alpha-Ketoglutarate in Low-Protein Diets for Growing Pigs: Effects on Cecal Microbial Communities and Parameters of Microbial Metabolism.pdf

<p>Alpha-ketoglutarate (AKG), a critical molecule in the tricarboxylic acid cycle, is beneficial to intestinal functions. However, its influence on intestinal microbiota and metabolism is not fully understood. We investigated the effects of a low-protein (LP) diet supplemented with AKG on cecal microbial communities and the parameters of microbial metabolism in growing pigs. Twenty-seven young pigs (Large White × Landrace) with an average initial body weight of 11.96 ± 0.18 kg were randomly allotted into three groups (n = 9): a normal protein (NP) diet containing 20% crude protein (CP); LP diet formulated with 17% CP (LP diet); or LP diet supplemented with 10 g kg^-1 of AKG (ALP diet). After a 35-day trial period, the digesta of the cecum were collected to analyze the concentrations of ammonia and short-chain fatty acids (SCFAs). We also performed a microbial analysis. Although no significant differences were found in performance among the diet groups, pigs fed the ALP diet had greater average daily gain (ADG) when compared with those in the LP group. Experimental diet did not affect cecal bacterial richness or diversity, as determined by Chao1 and ACE species richness measures and Shannon and Simpson indices, respectively. The predominant phyla Firmicutes, Bacteroidetes, and Proteobacteria increased in relative abundances in the cecum of pigs fed ALP diet. At the genus level, compared to the LP diet, the ALP diet significantly increased the abundances of Lachnospiraceae UCG-005, Lachnospiraceae NK4A136 group, Phascolarctobacterium and Parabacteroides, while decreased Vibrio and Maritalea. Pigs fed the ALP diet increased Oribacterium and Lachnoclostridium when compared with the NP diet. Non-metric multidimensional scaling analysis revealed that the distribution of microbiota at each group was distinctly clustered separately along principal coordinate. In addition, quantitative PCR revealed that the ALP diet was also associated with increases in the amounts of Bacteroides, Bifidobacterium, and Lactobacillus, but a decrease in the level of Escherichia coli. Compared with the NP diet, the ALP diet enhanced the concentrations of valerate and propionate. This ALP diet also increased the concentrations of valerate and isobutyrate when compared with the LP diet. Moreover, the ALP diet was linked with a significant decline in the concentration of ammonia in the cecum. These results indicate that a LP diet supplemented with AKG can alter the balance in microbial communities, increasing the population of SCFA-producing bacteria and the amounts of Bacteroides and Bifidobacterium, while reducing the counts of Escherichia coli and the amount of ammonia in the cecum.</p

Tuning the Self-Assembly of Short Peptides via Sequence Variations

Peptide self-assembly is of direct relevance to protein science and bionanotechnology, but the underlying mechanism is still poorly understood. Here, we demonstrate the distinct roles of the noncovalent interactions and their impact on nanostructural templating using carefully designed hexapeptides, I₂K₂I₂, I₄K₂, and KI₄K. These simple variations in sequence led to drastic changes in final self-assembled structures. β-sheet hydrogen bonding was found to favor the formation of one-dimensional nanostructures, such as nanofibrils from I₄K₂ and nanotubes from KI₄K, but the lack of evident β-sheet hydrogen bonding in the case of I₂K₂I₂ led to no nanostructure formed. The lateral stacking and twisting of the β-sheets were well-linked to the hydrophobic and electrostatic interactions between amino acid side chains and their interplay. For I₄K₂, the electrostatic repulsion acted to reduce the hydrophobic attraction between β-sheets, leading to their limited lateral stacking and more twisting, and final fibrillar structures; in contrast, the repulsive force had little influence in the case of KI₄K, resulting in wide ribbons that eventually developed into nanotubes. The fibrillar and tubular features were demonstrated by a combination of cryogenic transmission electron microscopy (cryo-TEM), negative-stain transmission electron microscopy (TEM), and small-angle neutron scattering (SANS). SANS also provided structural information at shorter scale lengths. All atom molecular dynamics (MD) simulations were used to suggest possible molecular arrangements within the β-sheets at the very early stage of self-assembly

Effects of Dietary Supplementation with Glutamate and Aspartate on Diquat-Induced Oxidative Stress in Piglets

<div><p>This study aimed to investigate the protective effects of dietary glutamate and aspartate supplementations on diquat-induced oxidative stress in piglets. Diquat injection significantly reduced growth performance, including body weight, average daily weight gain, and feed intake (P<0.05). Meanwhile, diquat administration induced oxidative stress evidenced by the decreased serum nitric oxide (NO) and elevated malondialdeyhde (MDA) concentration (P<0.05). Furthermore, diquat-induced oxidative stress disrupted intestinal absorption system and decreased serum threonine, serine, and glycine levels. Dietary supplementation with glutamate improved final body weight, antioxidant system, and expressions of amino acids transporters and enhanced serum glutamate concentration compared with diquat group (P<0.05). While aspartate failed to alleviate diquat-induced oxidative stress, growth depression, and dysfunction of nutrients absorption except for liver relative weight. In conclusion, dietary supplementation with glutamate confers beneficial effects on diquat-induced oxidative stress in piglets, while aspartate exhibits little effects.</p></div

Serum free amino acids in four groups.

<p>Serum free amino acids in four groups.</p

Intestinal relative mRNA abundances in four groups after exposure to diquat.

<p>Intestinal relative mRNA abundances in four groups after exposure to diquat.</p

Histological evaluation of intestinal tissues (HE×250) after exposure to diquat.

<p>Histological evaluation of intestinal tissues (HE×250) after exposure to diquat.</p

The intestinal villus height and crypt depth in four groups.

<p>The intestinal villus height and crypt depth in four groups.</p