Molecular hybridization combining tumor homing and penetrating peptide domains for cellular targeting.

A complete peptide-based drug delivery unit has been designed with a tumor homing domain chemically linked to a syndiotactic cell-penetrating domain. The designed peptides were synthesized, characterized, and tested in vitro for cellular uptake and cytotoxicity evaluation. The differential uptake, cellular internalization, negligible hemotoxicity, selective toxicity to MDA-MB-231 breast cancer cells, and the superior penetration in three-dimensional MDA-MB-231 tumorospheres confirm their utility as a promising delivery vector.

Geometry encoded functional programming of tumor homing peptides for targeted drug delivery.

Poly-peptide molecules have shown promising applications in drug delivery and tumor targeting. A series of tumor homing peptides were designed by exhaustively sampling low energy geometrical basins of amino acids at specific sites of a peptide molecule to induce a conformational lock. This peptide library was pruned to a limited set of eight molecules, employing electrostatic interactions, docking, and molecular dynamics simulations. These designed and optimized peptides were synthesized and tested on various cell lines, including breast cancer (MDA-MB-231), cervical cancer (HeLa), osteosarcoma (U2-OS), and non-cancerous mammary epithelial cells (MCF-10A) using confocal microscopy and flow cytometry. Peptides show differential uptake in cancerous MDA-MB-231, HeLa, U2-OS, and non-cancerous MCF-10A cells. Confocal imaging verified their ability to penetrate even in 3D tumorospheres of MDA-MB-231 cells. Further, experiments of mitochondrial membrane potential depolarization and Caspase-3 activation confirmed that their cytotoxic effects are by apoptosis. Homing ability of the designed peptides in in vivo system and fluorescence imaging with clinical samples of human origin have further confirmed that the in vitro studies are qualitatively identical and quantitatively comparable in their ability to selectively recognize tumor cells. Overall, we present a roadmap for the functional programming of peptide-based homing and penetrating molecules that can perform selective tumor targeting.

Conformationally constrained peptides for drug delivery.

Peptides have shown great potential in acting as template for developing versatile carrier platforms in nanomedicine, aimed at selective delivery of drugs to only pathological tissues saving its normal neighbors. Cell-penetrating peptides (CPPs) are short oligomeric peptides capable of translocating across the cell membrane while simultaneously employing multiple mechanisms of entry. Most CPPs exist as disordered structures in solution and may adopt a helical conformation on interaction with cell membrane, vital to their penetrative capability. Herein, we report a series of cationic helical amphipathic peptides (CHAPs), which are topologically constrained to be helical. The peptides were tested against cervical and breast cancer cells for their cell penetration and drug delivery potential. The cellular uptake of CHAP peptides is independent of temperature and energy availability. The activity of the peptides is biocompatible in bovine serum. CHAPs delivered functional methotrexate (MTX) inside the cell as CHAP-MTX conjugates. CHAP-MTX conjugates were more toxic to cancer cells than MTX alone. However, the CHAP-MTX conjugates were less toxic to HEK-293 cells compared with the cancer cells suggesting higher affinity towards cancer cells.

Peptide-based delivery vectors with pre-defined geometrical locks.

Design of peptide-based targeted delivery vectors with attributes of specificity and selective cellular targeting by fixing their topology and resulting electrostatic fingerprint is the objective of this study. We formulated our peptide design platform by utilizing the possibilities of side-chain induced geometric restrictions in a typical peptide molecule. Conceptually, we locked the conformation of the RGD/NGR motif of tumor homing peptides (THPs) by mutating glycine in these motifs with d-proline and tailed the peptides with a syndiotactic amphipathic segment for cellular penetration. The designed peptides were synthesized, characterized, and tested in vitro on various cell lines, including breast cancer (MDA-MB-231), cervical cancer (HeLa), osteosarcoma (U2-OS) and non-cancer mammary epithelial cells (MCF-10A), by flow cytometry and confocal microscopy. The results showed differential cellular uptake in different cell types, as a result of the distinct electrostatic fingerprint encoded in their design. The uptake of serum pre-treated peptides by cells reveals the retention of peptide activity even after the incubation with serum. In addition, peptide-methotrexate (MTX) conjugates compared to the methotrexate drug showed enhanced apoptotic cell death in MTX-resistant MDA-MB-231 cells, indicating the increase in MTX bioavailability.

Syndiotactic peptides for targeted delivery.

Lack of cell-type specificity and proteolytic susceptibility have long been the major bottlenecks for the development of peptide-based biomaterials for targeted drug delivery. Though a poly-l backbone provides the adaptability to re-conform the peptide structure to bind to a receptor, it also makes the peptide more susceptible to proteolytic cleavage. We have attempted to address this issue by designing a set of syndiotactic peptides de novo, with alternating l- and d-amino acids in succession. The designed peptides have higher rates of cellular uptake than the Tat (48-60) peptide in breast and cervical cancer cells. The uptake is independent of concentration, temperature and endocytosis (clathrin mediated). Importantly, the peptides are stable in both human plasma and bovine serum. The peptide-drug conjugates are much less toxic to the non-cancerous cells than cancer cells. The designed peptides are a step forward towards the development of targeted drug delivery vectors on peptide templates. STATEMENT OF SIGNIFICANCE: Present options in chemotherapy have multiple side effects arising from the lack of cell-type specificity, which makes them synonymous with "a Pyrrhic victory". Proteolytic susceptibility and non-specificity towards cancer cells has stunted the development of peptide-based biomaterials for targeted drug delivery. We have designed a set of peptides, addressing the above-mentioned roadblocks at an in vitro level. The peptides were designed on the template of a naturally existing peptide antibiotic from Bacillus brevis. The designed peptides have higher rates of cellular transduction than the model peptide (Tat), and is majorly membrane based. The peptides are stable in serum and selective towards cancer cells. Observations presented in this work can potentially take the discipline of de novo design of biomaterial conjugates forward.

Peptide based antimicrobials: Design strategies and therapeutic potential.

Therapeutic activity of antibiotics is noteworthy, as they are used in the treatment of microbial infections. Regardless of their utility, there has been a steep decrease in the number of drug candidates due to antibiotic resistance, an inevitable consequence of noncompliance with the full therapeutic regimen. A variety of resistant species like MDR (Multi-Drug Resistant), XDR (Extensively Drug-Resistant) and PDR (Pan Drug-Resistant) species have evolved, but discovery pipeline has already shown signs of getting dried up. Therefore, the need for newer antibiotics is of utmost priority to combat the microbial infections of future times. Peptides have some interesting features like minimal side effect, high tolerability and selectivity towards specific targets, which would help them successfully comply with the stringent safety standards set for clinical trials. In this review, we attempt to present the state of the art in the discovery of peptide-based antimicrobials from a design perspective.

Visual pedagogy and probiotics for hearing impaired children: A pilot study.

CONTEXT: Oral health care for children with special needs remains largely unmet. It is important that we should focus on preventive strategies for special children to help curtail and prevent oral diseases. AIM: This study aimed to assess the effect of visual pedagogy and probiotic mouth rinse on the periodontal health of hearing impaired children. MATERIALS AND METHODOLOGY: The study cohort consisted of twenty children with hearing impairment (HI) and 20 age-matched healthy children. The gingival index (GI), plaque index (PI), and salivary pH for all children were assessed at baseline, 15 days after oral hygiene training using visual pedagogy, 15 days after probiotic mouth rinse introduction, and at the end of the test period, i.e., 2 months after discontinuing probiotics. STATISTICAL ANALYSIS: Comparison of means was carried out using the Student's t-test. Intragroup parameters were assessed using the one-way ANOVA, followed by the post hoc Scheffe test. Value for statistical significance was fixed at 0.05. RESULTS: The GI and PI scores did not improve significantly after oral hygiene training in either of the two groups. The use of probiotic mouth rinse significantly reduced GI scores (<0.01) and PI scores (<0.01) and increased salivary pH above the critical pH in both groups. CONCLUSION: The use of visual pedagogy coupled with probiotic mouth rinsing may improve the periodontal status of children with HI and should be explored as a preventive procedure for children with special health-care needs.

Smoking re-initiation after cessation program: Comparison of associated factors between young and older adults.

OBJECTIVE: To evaluate the associated factors in reinitiating the smoking habit among the participants of a smoking cessation program conducted in a tobacco cessation clinic of Manipal University, Manipal. MATERIALS AND METHODS: This cross-sectional study was conducted among participants of a smoking cessation program who reinitiated smoking habit. A self-administered questionnaire was used that had information on demographic, habit history, knowledge on harmful effects of smoking behavior related to oral cavity and associated factors due to which individual was unable to quit the habit. RESULTS: A total of 102 males (mean age = 39.91 ± 9.57) constituted the final sample. The results showed that habitual smokers were more likely to be ≥40 years and occasional smokers were all reported to be <93 years (P < 0.001). Cigarette smokers were more likely to be of younger age group while majority of the Beedi and cigarette + Beedi smokers were older adults (P < 0.001). The mean duration of the habit was significantly higher for older adults than young adults (P < 0.001). There was no significant difference in the number of packs between the age groups (P = 0.054). A significantly higher proportion of young adults than older adults were aware about oral cancer (P < 0.001). Significantly higher proportion of older adults than young adults tend to have a closest person to be a smoker (P = 0.05). A significant higher proportion of young adults reason their habit as for pleasure (84.6%) and relaxation (68.8%), while older adults reason it to be as tension (64.1%) or combined factors (70.6%). Peer pressure was almost same in both the age groups (P = 0.006). There were no significant differences in the withdrawal symptoms among young and older adults (P = 0.41). CONCLUSION: Considerable differences were noticed between younger and older age groups in the factors which might play a role in re-intiating the smoking habit. A structured cessation program focused more on the above characteristics should be planned in public health programs based on the characteristics of the participants.