Norbornene-Derived Poly-d-lysine Copolymers as Quantum Dot Carriers for Neuron Growth

A Poly-D-lysine-Coated Coralline Matrix Promotes Hippocampal Neural Precursor Cells' Differentiation into GFAP-Positive Astrocytes

A major goal of regenerative medicine of the central nervous system is to accelerate the regeneration of nerve tissue, where astrocytes, despite their positive and negative roles, play a critical role. Thus, scaffolds capable of producing astrocytes from neural precursor cells (NPCs) are most desirable. Our study shows that NPCs are converted into reactive astrocytes upon cultivation on coralline-derived calcium carbonate coated with poly-D-lysine (PDL-CS). As shown via nuclei staining, the adhesion of neurospheres containing hundreds of hippocampal neural cells to PDL-CS resulted in disaggregation of the cell cluster as well as the radial migration of dozens of cells away from the neurosphere core. Migrating cells per neurosphere averaged 100 on PDL-CS, significantly higher than on uncoated CS (28), PDL-coated glass (65), or uncoated glass (20). After 3 days of culture on PDL-CS, cell migration plateaued and remained stable for four more days. In addition, NPCs expressing nestin underwent continuous morphological changes from round to spiky, extending and elongating their processes, resembling activated astrocytes. The extension of the process increased continuously during the maturation of the culture and doubled after 7 days compared to day 1, whereas bifurcation increased by twofold during the first 3 days before plateauing. In addition, nestin positive cells' shape, measured through the opposite circularity level correlation, decreased approximately twofold after three days, indicating spiky transformation. Moreover, nestin-positive cells co-expressing GFAP increased by 2.2 from day 1 to 7, reaching 40% of the NPC population on day 7. In this way, PDL-CS promotes NPC differentiation into reactive astrocytes, which could accelerate the repair of neural tissue.

Engineering Camptothecin-Derived Norbornene Polymers for Theranostic Application

A multifunctional stimuli-responsive nanotheranostic agent provides huge benefits in nanomedicine by combining both the diagnostic agent and the drug molecule in a single system. This nanosystem is capable of doing multiple tasks, for example, diagnosis, drug delivery, and monitoring the therapeutic response. Hence, theranostic agents are expected to play a significant role in personalized medicine. Herein, a new class of nanotheranostic agents, Pnr-Cbt-Cpt-Pg-Bn, is proposed for the effective delivery of camptothecin. This new class of polymer has been functionalized with a superparamagnetic norbornene cobalt unit for its use in magnetic resonance imaging (MRI). The NMR one-dimensional image confirms the MRI capability of this nanotheranostic agent. This is further modified with the poly(ethylene glycol)-biotin moiety for biocompatibility and site-specificity. The uniqueness of the design is confirmed by an in vitro study where a greater uptake of the nanotheranostic agent is observed when compared with free drugs. Hence, this new class of copolymer shows improved potential as nanotheranostic agents in drug delivery.

Biodegradable Copolymer for Stimuli-Responsive Sustained Release of Doxorubicin

Pendent functionalization of biodegradable polymers provides unique importance in biological applications. In this work, we have synthesized a polymeric nanocarrier for the controlled release of the anticancer drug doxorubicin (DOXI). Inspired by the pH responsiveness of acylhydrazine bonds along with the interesting self-assembly behavior of amphiphilic copolymers, this report delineates the development of a PEG-SS-PCL-DOXI copolymer consisting of DOXI, PEG, and a caprolactone backbone. First, the inclusion of a PEG moiety in the copolymer helps to achieve biocompatibility and aqueous solubility as well as a prolonged circulation time of the nanocarrier. Second, an acid-sensitive acylhydrazine-based linkage is chosen to attach DOXI to trigger sustained drug release, whereas the inclusion of an enzymatically cleavable disulfide linkage in the backbone adds to the advantage of backbone biodegradability at the intracellular level.

Estudo das células Neuro2A sobre os biomateriais PCL e PLLA

Os biomateriais poli L-ácido lático (PLLA) e o poli caprolactona (PCL) são os polímeros mais estudadas na área dos materiais bioreabsorvíveis. Dentre as suas principais características que contribuem para a interação celular, temos a especificidade química da superfície, elétrica, hidrofobicidade e topografia. Ainda, observa-se o tempo de degradação, porosidade, biocompatibilidade com o tecido biológico, bem como, a confecção com as mais variadas formas e dimensões. Já a prática da cultura celular, tem como objetivo estudar a adesão, migração, diferenciação e a proliferação celular utilizando-se um determinado material ou substância. Contudo, poucos trabalhos utilizando os biomateriais ora supracitados e a aplicação em células neuro2A foram realizados. Sabe-se que este tipo celular é derivado de células embrionárias da crista neural, as quais originam em neurônios simpáticos e apresentam como característica a imortalidade, portanto, são excelentes modelos em ensaios in vitro. Nesse sentido, o presente estudo avalia a adesão e a proliferação desta linhagem celular sobre os biopolímeros poli caprolactona (PCL) e poli L-ácido lático (PLLA).

Magnetic norbornene polymer as multiresponsive nanocarrier for site specific cancer therapy

A site-specific, stimuli-responsive nanocarrier has been synthesized by conjugating folate, magnetic particles and doxorubicin to the backbone of norbornene polymer. Monomers, namely, cis-5-norbornene-6-(diethoxyphosphoryl)hexanote (mono 1), norbornene grafted poly(ethyleneglycol)-folate (mono 2), and norbornene derived doxorubicin (mono 3) are carefully designed to demonstrate the smart nanorcarrier capabilities. The synthesis and complete characterization of all three monomers are elaborately discussed. Their copolymerization is done by controlled/living ring-opening metathesis polymerization (ROMP) to get the triblock copolymer PHOS-FOL-DOX. NMR spectroscopy and gel permeation chromatography confirm the formation of the triblock copolymer, while FT-IR spectroscopy, thermogravimetric analysis, along with transmission electron microscope confirm the anchoring of iron particle (Fe3O4) to the PHOS-FOL-DOX. Drug release profile shows the importance of having the hydrazone linker that helps to release the drug exactly at the mild acidic conditions resembling the pH of the cancerous cells. The newly designed nanocarrier shows greater internalization (about 8 times) due to magnetic field. Also, increased intracellular DOX release is observed due to the folate receptor. From these results, it is clear that PHOS-FOL-DOX has the potential to act as a smart nanoreservoir with the magnetic field guidance, folate receptor targeting, and finally pH stimulation.

Functionalized single walled carbon nanotubes facilitate efficient differentiation of neuroblastoma cells in vitro

Single-walled carbon nanotubes (SWNTs) have been increasingly used as scaffolds for neuronal growth and differentiation.

Efficient approach to prepare multiple chemotherapeutic agent conjugated nanocarrier

A pH-responsive, multiple chemotherapeutic agent derived nanocarrier has been synthesized by conjugating doxorubicin, indomethacin, and folate to the backbone of norbornene polymer.