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The self-assembly of lipopeptide (peptide amphiphile) molecules bearing single linear lipid chains has been widely studied, as has their diverse range of bioactivities. Here, we introduce lipopeptides bearing one or two cycloalkane chains (cycloheptadecyl or cyclododecyl) conjugated to the collagen-stimulating pentapeptide KTTKS used in Matrixyl formulations. The self-assembly of all four molecules is probed using fluorescence probe measurements to detect the critical aggregation concentration (CAC), and cryogenic-TEM and small-angle X-ray scattering (SAXS) to image the nanostructure. The peptide conformation is studied using circular dichroism (CD) and FTIR spectroscopies. All the cycloalkane lipopeptides show excellent compatibility with dermal fibroblasts. The compounds bearing one or two cyclododecyl chains (denoted as DKT and DDKT, respectively) show wound healing in diabetic rats, the improvement being markedly enhanced for DDKT. Interestingly, the revival of hair follicles and blood vessels in the dermis were observed, which are the critical markers of effective wound repair. Analysis of H&E-stained tissue images (from a rat model) shows that the rat groups treated with DDKT and DKT displayed a significantly increased amount of regenerated hair follicles, indicating a faster healing process for DDKT compared to the control group. Collagen deposition was also enhanced, especially for DDKT, and by day 20, the DDKT-treated groups had developed a dense collagen network accompanied by a regenerated epidermis. At the same time, the number of blood vessels in DDKT-treated diabetic wounds was significantly higher than in control groups and neovascularization was substantially enhanced, as assayed using α-SMA (a marker for vascular smooth muscle cells) and CD31 (a marker specific to vascular endothelial cells). These results suggest that the lead lipopeptide DDKT exhibits a remarkable pro-vascularization capability and shows great promise for future application as a wound-healing biomaterial.

The conformation and self-assembly of two pairs of model lipidated tripeptides in aqueous solution are probed using a combination of spectroscopic methods along with cryogenic-transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS). The palmitoylated lipopeptides comprise C16-YKK or C16-WKK (with two l-lysine residues) or their respective derivatives containing d-lysine (k), i.e., C16-Ykk and C16-Wkk. All four molecules self-assemble into spherical micelles which show structure factor effects in SAXS profiles due to intermicellar packing in aqueous solution. Consistent with micellar structures, the tripeptides in the coronas have a largely unordered conformation, as probed using spectroscopic methods. The molecules are found to have good cytocompatibility with fibroblasts at sufficiently low concentrations, although some loss of cell viability is noted at the highest concentrations examined (above the critical aggregation concentration of the lipopeptides, determined from fluorescence dye probe measurements). Preliminary tests also showed antimicrobial activity against both Gram-negative and Gram-positive bacteria.

Protein–protein interactions play a crucial role in microtubule dynamics. Microtubules are considered as a key target for the design and development of anticancer therapeutics, where inhibition of tubulin–tubulin interactions plays a crucial role. Here, we focused on a few key helical stretches at the interface of α,β-tubulin heterodimers and developed a structural mimic of these helical peptides, which can serve as potent inhibitors of microtubule polymerization. To induce helicity, we have made stapled analogues of these sequences. Thereafter, we modified the lead sequences of the antimitotic stapled peptides with halo derivatives. It is observed that halo-substituted stapled peptides follow an interesting trend for the electronegativity of halogen atoms in interaction patterns with tubulin and a correlation in the toxicity profile. Remarkably, we found that para-fluorophenylalanine-modified stapled peptide is the most potent inhibitors, which perturbs microtubule dynamics, induces apoptotic death, and inhibits the growth of melanoma.

The microtubule is regarded as the key target for designing anticancer and neurotherapeutic drugs due to its functional importance in eukaryotic cells including neurons. The microtubule is a dynamic hollow polymer tube consisting of α,β-tubulin heterodimer. Polymerization of α,β-tubulin heterodimer resulted in microtubule formation. GTP plays a crucial role in microtubule polymerization. It binds at the exchangeable binding site of the β-tubulin heterodimer, and it is one of the most crucial therapeutic hot spots for designing anticancer therapeutics. In this manuscript, we have shown using an in silicostrategy and various in vitroand cellular experiments that the binding affinity to the tubulin and cancer therapeutic potential of an exchangeable GTP/GDP binding antimitotic tetrapeptide (SP: Ser-Leu-Arg-Pro) is increased through changing proline with the multifluorine substituted proline. This study showcases the importance of the proline amino acid and its pyrrolidine ring in the regulation of binding with tubulin at the GTP binding pocket.

Brain injury can lead to the loss of neuronal functions and connections, along with the damage of the extracellular matrix (ECM). Thus, it ultimately results in devastating long-term damage, and recovery from this damage is a challenging task. To address this issue, we have designed a sulfo-group-functionalized injectable biocompatible peptide hydrogel, which not only mimics the ECM and supports the damaged neurons but also releases a neurotrophic factor around the injured sites of the brain in the presence of the matrix metalloproteinase 9 (MMP9) enzyme. It has also been observed that the driving force of hydrogel formation is a β-sheet secondary structure and π–π stacking interactions between Phe-Phe moieties. The hydrogel is able not only to promote neurite outgrowth of PC12-derived neurons and primary neurons cultured in its presence but also to nullify the toxic effects of anti-nerve growth factor (Anti-NGF)-induced neurons. It also promotes the expression of vital neuronal markers in rat cortical primary neurons, displays substantial potential in neuroregeneration, and also promotes fast recovery of the sham injured mice brain. Increased expression of reactive astrocytes in the hippocampal dentate gyrus region of the sham injured brain clearly suggests its tremendous ability in the neural repair of the damaged brain. Thus, we can convincingly state that our hydrogel is capable of repairing brain injury by mimicking an ECM-like environment and providing neuroprotection to the damaged neurons.

A biocompatible hydrogel containing a hexapeptide as a key unit has been designed and fabricated. Our design construct comprises a β-sheet-rich short hexapeptide in the center with a hydrophobic long chain and hydrophilic triple lysine unit attached at the N- and C-terminals, respectively. Thus, it is this amphiphilic nature of the molecule that facilitates gelation. It can capture solvent molecules in the three-dimensional cross-linked fibrillar networks. The amphiphilic character of the construct has been modulated to produce an excellent biocompatible soft material for the inhibition of bacterial growth by rupturing the bacterial cell membrane. This hydrogel is also stable against enzymatic degradation (proteinase K) and, most importantly, offers a biocompatible environment for the growth of normal mammalian cells due to its noncytotoxic nature as observed through the cell viability assay. From the hemolytic assay, the morphology of the human red blood cells is found to be almost intact, which suggests that the hydrogel can be used in biomedical applications. Thus, this newly designed antibacterial hydrogel can be used as both an antibacterial biomaterial and a biocompatible scaffold for mammalian cell culture.

A novel neuro-compatible peptide-based hydrogel has been designed and developed, which contains microtubule stabilizing and neuroprotective short peptide. This hydrogel shows strong three-dimensional cross-linked fibrillary networks, which can capture water molecules. Interestingly, this hydrogel serves as excellent biocompatible soft material for 2D and 3D (neurosphere) neuron cell culture and provides stability of key cytoskeleton filaments such as microtubule and actin. Remarkably, it was observed that this hydrogel slowly enzymatically degrades and releases neuroprotective peptide, which promotes neurite outgrowth of neuron cell as well as exhibits excellent neuroprotection against anti-NGF-induced toxicity in neuron cells. Further, it can encapsulate anti-Alzheimer and anticancer hydrophobic drug curcumin, releases slowly, and inhibits significantly the growth of a 3D spheroid of neuron cancer cells. Thus, this novel neuroprotective hydrogel can be used for both neuronal cell transplantation for repairing brain damage as well as a delivery vehicle for neuroprotective agents, anti-Alzheimer, and anticancer molecules.