scholarly journals Strategies for the Development of pH-Responsive Synthetic Polypeptides and Polymer-Peptide Hybrids: Recent Advancements

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 624
Author(s):  
Cintya Dharmayanti ◽  
Todd A. Gillam ◽  
Manuela Klingler-Hoffmann ◽  
Hugo Albrecht ◽  
Anton Blencowe

Synthetic polypeptides and polymer-peptide hybrid materials have been successfully implemented in an array of biomedical applications owing to their biocompatibility, biodegradability and ability to mimic natural proteins. In addition, these materials have the capacity to form complex supramolecular structures, facilitate specific biological interactions, and incorporate a diverse selection of functional groups that can be used as the basis for further synthetic modification. Like conventional synthetic polymers, polypeptide-based materials can be designed to respond to external stimuli (e.g., light and temperature) or changes in the environmental conditions (e.g., redox reactions and pH). In particular, pH-responsive polypeptide-based systems represent an interesting avenue for the preparation of novel drug delivery systems that can exploit physiological or pathological pH variations within the body, such as those that arise in the extracellular tumour microenvironment, intracellularly within endosomes/lysosomes, or during tissue inflammation. Here, we review the significant progress made in advancing pH-responsive polypeptides and polymer-peptide hybrid materials during the last five years, with a particular emphasis on the manipulation of ionisable functional groups, pH-labile linkages, pH-sensitive changes to secondary structure, and supramolecular interactions.

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1273 ◽  
Author(s):  
Huacheng Zhang ◽  
Zhaona Liu ◽  
Jian Shen

Recent progress about a novel organic–inorganic hybrid materials, namely cyclodextrins (CDs) modified/coated metal–organic frameworks (MOFs) is summarized by using a special categorization method focusing on the interactions between CDs and MOFs moieties, such as ligand–metal cations interactions, supramolecular interactions including host–guest interactions and hydrogen bonding, as well as covalent bonds. This review mainly focuses on the interactions between CDs and MOFs and the strategy of combining them together, diverse external stimuli responsiveness of CDs-modified/coated MOFs, as well as applications of these hybrid materials to drug delivery and release system, catalysis and detection materials. Additionally, due to the importance of investigating advanced chemical architectures and physiochemical properties of CDs-modified/coated MOFs, a separate section is involved in diverse characterization methods and instruments. Furthermore, this minireview also foresees future research directions in this rapidly developing field.


2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Brittany Umer ◽  
David Good ◽  
Jozef Anné ◽  
Wei Duan ◽  
Ming Q. Wei

Solid tumour accounts for 90% of all cancers. The current treatment approach for most solid tumours is surgery, however it is limited to early stage tumours. Other treatment options such as chemotherapy and radiotherapy are non-selective, thus causing damage to both healthy and cancerous tissue. Past research has focused on understanding tumour cells themselves, and conventional wisdom has aimed at targeting these cells directly. Recent research has shifted towards understanding the tumour microenvironment and it’s differences from that of healthy cells/tissues in the body and then to exploit these differences for treatmeat of the tumour. One such approach is utilizing anaerobic bacteria. Several strains of bacteria have been shown to selectively colonize in solid tumours, making them valuable tools for selective tumour targeting and destruction. Amongst them, the anaerobicClostridiumhas shown great potential in penetration and colonization of the hypoxic and necrotic areas of the tumour microenvironment, causing significant oncolysis as well as enabling the delivery of therapeutics directly to the tumourin situ. Various strategies utilizingClostridiumare currently being investigated, and represent a novel area of emerging cancer therapy. This review provides an update review of tumour microenvironment as well as summary of the progresses and current status of Clostridial spore-based cancer therapies.


2021 ◽  
Author(s):  
Mehboobali Pannipara ◽  
Abdullah G Al-Sehemi

Abstract Carboxylic acid supramolecular synthon exhibited dimer or catemer motifs in the crystal lattice depend on the substituent and other functional groups present in the structure. In general, presence of other competing functional groups produced catemer motifs whereas unsubstituted acids showed dimer. In this manuscript, we have synthesized a new aryl ether amine-based Schiff base with carboxylic acid functionality ( 1 ) and demonstrated polymorphic structure via catemer ( 1a ) and dimer ( 1b ) motifs in the solid state. In both the structure, carboxylic acid group adopted different orientation in the crystal lattice. The different H-bonding lead to modulation of optical properties that was further supported highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) calculation. Further the stability calculation indicates that catemer structure was more stable by 8.54 kcal/mole relative to dimer motifs. In contrast, naphthyl group attached carboxylic acid structure did not show neither dimer nor catemer motifs in the crystal lattice as compared to diethylaminophenyl group, which confirm the presence of other substituent or competing functional groups strongly influence on the motifs of supramolecular interactions.


GYMNASIUM ◽  
2017 ◽  
Vol XVII (1) ◽  
Author(s):  
Alina Mihaela Cristuță

Posture expresses the way in which the body receives external stimuli and gets ready to react, constantly adapting to the demands, according to the difficulty and to the individual's motor skills. The aim of this study is to educate the correct body posture through specific physical therapy means. The hypotheses presume that: by performing a specific assessment, one can spot the bad postures that are frequently adopted by school children; through specific intervention programs, one can educate, correct, and form a correct posture reflex. The objectives were to: assess the school children in order to spot physical deficiencies; to educate a correct posture and to form a correct posture reflex. The research methods were established according to the objectives. In the end, it can be concluded that this research  regarding the education of posture in school children has contributed to the prevention of instalment of physical deficiencies and to their correction, and the intervention measures were effective in educating the correct body posture.


PEDIATRICS ◽  
1951 ◽  
Vol 7 (2) ◽  
pp. 269-293
Author(s):  
CHARLES C. CHAPPLE

A study has been made of the known phenomena which affect the biologic organism. Certain correlations have been found and other correlations are logically inferred. The common grounds of anatomic structures, the anatomic responses to endocrine stimuli, the interrelationships and interdependencies of the endocrines and external stimuli have been followed and have been related to cellular permeability and hyaluronic acid. Cellular phases, including the rhythmic alternations in physiologic functions, have been delineated and their importance stressed. Further, the probability is advanced that this rhythmicity originates physiologically in the brain but that the brain itself is capable of receiving transmissions from within and without the body, and disseminating them, again rhythmically, in normal or altered amplitude and frequency. Further experimental evidence of these correlations and their practical extrapolations into drug actions and the therapy of infections and metabolic disease will be reported and will include clinical, animal and in vitro studies. At present, the following conclusions seem justified: 1. No component of the body is capable of independent action. 2. Action in any component is reflected, according to its magnitude and directness of application, upon all the body. 3. All such actions are mediated by the brain. 4. There is a dynamic, rhythmic cyclicity in physiologic action which can be altered in amplitude and frequency. 5. These rhythms are alternations of cellular tenseness and relaxation. 6. The concomitants of the tense phase are compactness, impermeability, electric conductivity and contraction of all cells, and these characteristics might be described collectively as the factors operative in maturing the cell. The concomitants of the relaxed phase are laxness, permeability, electric resistance and expansion of all cells and are factors of growth. 7. The phase of tenseness is accompanied by an increase in certain hormonal activities and that of relaxation by an increase in others. 8. The hormones may be causes of the phase or the results of it. 9. Infectious disease cannot act as an extraneous agent capable of bringing its own engine into such a highly integrated mechanism but must act on the body through its ability to affect one of the body's mechanisms. 10. Drugs must act through the same channels available to disease. 11. Foods may contain, in addition to their caloric content, components capable of stimulating either the phase of cellular expansion or cellular compaction, particularly foods from the reproductive systems of plants or animals (milk, eggs, cereal, for example). 12. Vitamins each stimulate one phase and should be evaluated in terms of positive actions. 13. Inherent growth and maturation factors are not of fixed capacity in an individual but beyond certain limits must be supplied him or applied to him constantly. 14. The hormone most manifest in the tense phase is estrogen and so may be considered the maturation factor, and the one most manifest in the phase of relaxation or cell division is progesterone, which may be considered the growth factor.


2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Dinesh K. Patel ◽  
Yu-Ri Seo ◽  
Ki-Taek Lim

Stimuli-responsive materials, also known as smart materials, can change their structure and, consequently, original behavior in response to external or internal stimuli. This is due to the change in the interactions between the various functional groups. Graphene, which is a single layer of carbon atoms with a hexagonal morphology and has excellent physiochemical properties with a high surface area, is frequently used in materials science for various applications. Numerous surface functionalizations are possible for the graphene structure with different functional groups, which can be used to alter the properties of native materials. Graphene-based hybrids exhibit significant improvements in their native properties. Since functionalized graphene contains several reactive groups, the behavior of such hybrid materials can be easily tuned by changing the external conditions, which is very useful in biomedical applications. Enhanced cell proliferation and differentiation of stem cells was reported on the surfaces of graphene-based hybrids with negligible cytotoxicity. In addition, pH or light-induced drug delivery with a controlled release rate was observed for such nanohybrids. Besides, notable improvements in antimicrobial activity were observed for nanohybrids, which demonstrated their potential for biomedical applications. This review describes the physiochemical properties of graphene and graphene-based hybrid materials for stimuli-responsive drug delivery, tissue engineering, and antimicrobial applications.


2020 ◽  
Vol 14 (2) ◽  
pp. 134-153 ◽  
Author(s):  
A. S. Herc ◽  
M. Wlodarska ◽  
M. Nowacka ◽  
J. Bojda ◽  
W. Szymanski ◽  
...  

1892 ◽  
Vol 36 (2) ◽  
pp. 321-333 ◽  
Author(s):  
W. G. Aitchison Robertson

Clinical and pathological observation both show that the dentine of the tooth is very closely connected with the nervous system, and is in consequence highly sensitive. Upon what structures does the sensibility of the dentine depend? In what manner is the dentine connected with the nerves of the pulp so as to become so sensitive to external stimuli?Perhaps there is no other structure in the body which is so largely supplied with nerves as the pulp of the tooth; even in the smallest fragment we find many nerve fibres. If we take the pulp from the incisor tooth of an ox and examine it after having allowed it to lie in a solution of osmic acid for a few minutes, we can see clearly through the darkened semi-transparent tissue a large blackened nerve trunk passing up the centre of the pulp, giving off on its way innumerable lateral branches, and dividing in a brush-like manner near the upper part of the pulp. All the fine branches are directed towards the periphery of the pulp. In longitudinal sections of the pulp we can see the same in greater detail; many large bundles of medullated and non-medullated nerve fibres running longitudinally near the centre and giving off lateral branches, which are found in great numbers near the periphery and divide into single nerve fibres just under the odontoblastic layer, being specially numerous at the apex of the pulp.


Author(s):  
Ramana M. Pidaparti ◽  
Kevin R. Ward

Inflammation has been recognized as a major integral component for most of the acute and chronic diseases. Inflammation can be initiated within the body as an innate process or by external factors such as infections and trauma. Inflammation is a complex and dynamic process, and involves nonlinearity and stochasticity. Without the inflammation, the harmful stimuli cannot be removed and the healing process cannot occur. However, an over-expression or under-expression of inflammatory responses can lead to severe consequences, such as Multiple Organ Dysfunction Syndrome (MODS), which is characterized by sequential organ failure. Acute lung injury (ALI) is typically one of the first manifestation of MODS. It can be triggered by external stimuli such as pathogens or from inflammatory mediators produced from various other processes ranging from other damaged organs or to blood transfusions to even the biomechanical forces of mechanical ventilation itself.


2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Zheling Feng ◽  
Jun Cao ◽  
Qingwen Zhang ◽  
Ligen Lin

AbstractInflammation is an active defense response of the body against external stimuli. Long term low-grade inflammation has been considered as a deteriorated factor for aging, cancer, neurodegeneration and metabolic disorders. The clinically used glucocorticoids and non-steroidal anti-inflammatory drugs are not suitable for chronic inflammation. Therefore, it’s urgent to discover and develop new effective and safe drugs to attenuate inflammation. Clerodane diterpenoids, a class of bicyclic diterpenoids, are widely distributed in plants of the Labiatae, Euphorbiaceae and Verbenaceae families, as well as fungi, bacteria, and marine sponges. Dozens of anti-inflammatory clerodane diterpenoids have been identified on different assays, both in vitro and in vivo. In the current review, the up-to-date research progresses of anti-inflammatory clerodane diterpenoids were summarized, and their druglikeness was analyzed, which provided the possibility for further development of anti-inflammatory drugs.


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