Quantum dots have unique optical properties that make them useful fluorescent probes for cellular and in vivo imaging. They have broad absorption spectra and narrow, size-dependent emission spectra. Making hydrophobic quantum dots water-soluble involves coating them with bifunctional ligands, encapsulating them in micelles or liposomes, or polymer coating. Quantum dots can be conjugated to biomolecules like avidin and used for multiplexed imaging. They have advantages over organic dyes like greater photostability and brightness. Quantum dots have been used for various cellular imaging applications as well as in vivo imaging of vasculature, receptors, and other targets.
here you can find the most rare topics in detail
all fields of chemistry are deeply understood here for presenting the lectures
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Different types of methods can be used for the preparation of Magnetic Nanoparticles, their advantages and disadvantages and applications of the materials in various fields are given in the presentation
here you can find the most rare topics in detail
all fields of chemistry are deeply understood here for presenting the lectures
stay blessed and keep supporting
Different types of methods can be used for the preparation of Magnetic Nanoparticles, their advantages and disadvantages and applications of the materials in various fields are given in the presentation
The following presentation is only for quick reference. I would advise you to read the theoretical aspects of the respective topic and then use this presentation for your last minute revision. I hope it helps you..!!
Mayur D. Chauhan
Dynamic light scattering (DLS) or Quasi-Elastic Light Scattering (QELS), is a non-invasive, well-established technique for measuring the size and size distribution of molecules and particles typically in the submicron region, and with the latest technology lower than 1nm.
In This slide the working principle and the function of DLS is Explained in brief and precise way.
Classification of Nanostructures by Peeyush MishraPeeyush Mishra
In this presentation, I have tried to define Nanostructures and discuss various types of Nanostructures. I have also compared the ways in which Nanomaterials can be synthesized.
Review paper on the applications and challenges of gold nanoparticles in medicine and dentistry.
Gold nanoparticles is a game-changer in delivering patient care. Its versatility can be put to use in diagnosis, imaging and treatment of various conditions. It relatively recent innovation although gold is a metal that has had a lot of meaning in human civilisation.With a lot of potential left unexplored one has to what and watch the miracles this breakthrough has in store for medical science.
Nanoparticles are solid colloidal particles ranging in size from 10 to 1000 nm.
Nanoparticles are made of a macromolecular material which can be of synthetic or natural origin.
Metallic nanoparticles (MNPs) is a type of nanoparticle which have a metal core composed of inorganic metal or metal oxide that is usually covered with a shell made up of organic or inorganic material or metal oxide.
Dynamic light scattering (DLS) is a technique in physics that can be used to determine the size distribution profile of small particles in suspension or polymers in solution.
Other names are
Photon correlation spectroscopy
Quasi-elastic light scattering.
Nanomaterials in biomedical applicationsumeet sharma
An introduction to emerging technology in medicinal science, "nanodrugs" a fruitful combination of nano-science and medical science. In this presentation, use of nano shells for delivery of drugs to targeted cancer cells has been explained. along with In Vivo and In Vitro studies on use of nanomaterials for biomedical application. For any information please feel free to contact me or refer to the references.
The engineered nanoparticles are effectively used for cancer treatment due to their targeted drug delivery approach. Download the Aranca report on Technology and Patent Research for current research trends and developments.
The following presentation is only for quick reference. I would advise you to read the theoretical aspects of the respective topic and then use this presentation for your last minute revision. I hope it helps you..!!
Mayur D. Chauhan
Dynamic light scattering (DLS) or Quasi-Elastic Light Scattering (QELS), is a non-invasive, well-established technique for measuring the size and size distribution of molecules and particles typically in the submicron region, and with the latest technology lower than 1nm.
In This slide the working principle and the function of DLS is Explained in brief and precise way.
Classification of Nanostructures by Peeyush MishraPeeyush Mishra
In this presentation, I have tried to define Nanostructures and discuss various types of Nanostructures. I have also compared the ways in which Nanomaterials can be synthesized.
Review paper on the applications and challenges of gold nanoparticles in medicine and dentistry.
Gold nanoparticles is a game-changer in delivering patient care. Its versatility can be put to use in diagnosis, imaging and treatment of various conditions. It relatively recent innovation although gold is a metal that has had a lot of meaning in human civilisation.With a lot of potential left unexplored one has to what and watch the miracles this breakthrough has in store for medical science.
Nanoparticles are solid colloidal particles ranging in size from 10 to 1000 nm.
Nanoparticles are made of a macromolecular material which can be of synthetic or natural origin.
Metallic nanoparticles (MNPs) is a type of nanoparticle which have a metal core composed of inorganic metal or metal oxide that is usually covered with a shell made up of organic or inorganic material or metal oxide.
Dynamic light scattering (DLS) is a technique in physics that can be used to determine the size distribution profile of small particles in suspension or polymers in solution.
Other names are
Photon correlation spectroscopy
Quasi-elastic light scattering.
Nanomaterials in biomedical applicationsumeet sharma
An introduction to emerging technology in medicinal science, "nanodrugs" a fruitful combination of nano-science and medical science. In this presentation, use of nano shells for delivery of drugs to targeted cancer cells has been explained. along with In Vivo and In Vitro studies on use of nanomaterials for biomedical application. For any information please feel free to contact me or refer to the references.
The engineered nanoparticles are effectively used for cancer treatment due to their targeted drug delivery approach. Download the Aranca report on Technology and Patent Research for current research trends and developments.
Relative Morphology of Extraembryonic Membranes in Mammals: Their Roles in Hi...Joseph Holson
Presented by John DeSesso and Joseph F. Holson in Symposium I ("A Detective Story: Is the Prenatal Toxicity of a Therapeutic in Rats Relevant to Human Risk?", J.F. Holson and L. B. Pearce, co-chairpersons) at the Forty-Third Annual Meeting of the Teratology Society, Philadelphia, PA, June 26, 2003.
This presentation will provide you the details of a special category of the so called Medical Nanorobots known as "Microbivores" or the artificial white blood cells.
know more about nanomaterials and its apllication in future as well as current situation, and what wil we reserch on basis of nanomaterials and carbon structure and its aplication in such futuriastic manner.
nanotechnology. INTRODUCTION TO BIONANOTECHNOLOGY
Group : L01-B01 (LAB)
Class Date & Time : 02-Apr-2024, 08:00 - 10:00 AM
All students will be tagged as ABSENT until student scanned QR code OR lecturer manually update attendance status
Construction and design of a novel drug delivery systemBalaganesh Kuruba
Over the years upon the evolution in the field of nanotechnology various materials are introduced and its applications are being explored in reality proving its usefulness. Applications of the same in drug/gene delivery systems is being carried out since past decade and unbelievable results are being achieved. However, problem lying in these techniques being either in cellular uptake of the material or the degradability of the material being used. My work shall concentrate upon introducing a biocompatible and inert systems with molecules fabricated on the surface triggering cellular intake. Genetic system implemented in the system shall rely upon the mechanism of Viral genes assisted integration of the "GOI (Gene of Interest)" into the target specific location in the nucleus. And the GOI is also tagged with the Green Fluorescent Protein expressing Gene so as to confirm the presence of integration of GOI into the genome. This method shall provide a fast , reliable and non-invasive method of tracking down the delivery system from the point of injection to until it delivers the cargo.
Abstract
In the last decade, developments in nanotechnology have provided a new field in medicine called “Nanomedicine”. Nanomedicine has provided new tools for photodynamic therapy. Quantum dots (QDs) are approximately spherical nanoparticles that have attracted broad attention and have been used in nanomedicine applications. QDs have high molar extinction coefficients and photoluminescence quantum yield, narrow emission spectra, broad absorption, large effective stokes shifts. QDs are more photostable and resistant to metabolic degradation. These photosensitizing properties can be used as photosensitizers for Photodynamic Therapy (PDT). PDT has been recommended for its unique characteristic, such as low side effect and more efficiency. Therefore, nanomedicine leads a promising future for targeted therapy in cancer tumor. Furthermore, QDs have recently been applied in PDT, which will be addressed in this review letter. Also this review letter evaluates key aspects of nano-particulate design and engineering, including the advantage of the nanometer scale size range, biological behavior, and safety profile.
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This 60-minute webinar, sponsored by Adobe, was delivered for the Training Mag Network. It explored the five elements of SPARK: Storytelling, Purpose, Action, Relationships, and Kudos. Knowing how to tell a well-structured story is key to building long-term memory. Stating a clear purpose that doesn't take away from the discovery learning process is critical. Ensuring that people move from theory to practical application is imperative. Creating strong social learning is the key to commitment and engagement. Validating and affirming participants' comments is the way to create a positive learning environment.
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Enterprise Excellence is Inclusive Excellence.pdfKaiNexus
Enterprise excellence and inclusive excellence are closely linked, and real-world challenges have shown that both are essential to the success of any organization. To achieve enterprise excellence, organizations must focus on improving their operations and processes while creating an inclusive environment that engages everyone. In this interactive session, the facilitator will highlight commonly established business practices and how they limit our ability to engage everyone every day. More importantly, though, participants will likely gain increased awareness of what we can do differently to maximize enterprise excellence through deliberate inclusion.
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Falcon stands out as a top-tier P2P Invoice Discounting platform in India, bridging esteemed blue-chip companies and eager investors. Our goal is to transform the investment landscape in India by establishing a comprehensive destination for borrowers and investors with diverse profiles and needs, all while minimizing risk. What sets Falcon apart is the elimination of intermediaries such as commercial banks and depository institutions, allowing investors to enjoy higher yields.
The world of search engine optimization (SEO) is buzzing with discussions after Google confirmed that around 2,500 leaked internal documents related to its Search feature are indeed authentic. The revelation has sparked significant concerns within the SEO community. The leaked documents were initially reported by SEO experts Rand Fishkin and Mike King, igniting widespread analysis and discourse. For More Info:- https://news.arihantwebtech.com/search-disrupted-googles-leaked-documents-rock-the-seo-world/
Memorandum Of Association Constitution of Company.pptseri bangash
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A Memorandum of Association (MOA) is a legal document that outlines the fundamental principles and objectives upon which a company operates. It serves as the company's charter or constitution and defines the scope of its activities. Here's a detailed note on the MOA:
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Name Clause: This clause states the name of the company, which should end with words like "Limited" or "Ltd." for a public limited company and "Private Limited" or "Pvt. Ltd." for a private limited company.
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Registered Office Clause: It specifies the location where the company's registered office is situated. This office is where all official communications and notices are sent.
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Capital Clause: This clause specifies the authorized capital of the company, i.e., the maximum amount of share capital the company is authorized to issue. It also mentions the division of this capital into shares and their respective nominal value.
Association Clause: It simply states that the subscribers wish to form a company and agree to become members of it, in accordance with the terms of the MOA.
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Legal Requirement: The MOA is a legal requirement for the formation of a company. It must be filed with the Registrar of Companies during the incorporation process.
Constitutional Document: It serves as the company's constitutional document, defining its scope, powers, and limitations.
Protection of Members: It protects the interests of the company's members by clearly defining the objectives and limiting their liability.
External Communication: It provides clarity to external parties, such as investors, creditors, and regulatory authorities, regarding the company's objectives and powers.
https://seribangash.com/difference-public-and-private-company-law/
Binding Authority: The company and its members are bound by the provisions of the MOA. Any action taken beyond its scope may be considered ultra vires (beyond the powers) of the company and therefore void.
Amendment of MOA:
While the MOA lays down the company's fundamental principles, it is not entirely immutable. It can be amended, but only under specific circumstances and in compliance with legal procedures. Amendments typically require shareholder
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4. What are quantum dots
• Unique Spectral properties
Broad absorption
Narrow emission
Wavelength depends on size
CdSe/ZnS
QD
samples
Annu. Rev. Anal. Chem. 2013. 6:143–62, Michalet , X. et al. Science. 2005, 307 , 538 – 44
5. Making hydrophobic quantum dots biocompatible
• Various methods for
making them watersoluble
– Derivatizing surface
with bifunctional
ligands
– Encapsulating in
phospholipid
micelles or liposomes
– Polymer coating
Gao , X. et al. Adv.Experim.Med.
Biol. 2007, 620,57-73
6. Conjugating quantum dots to biomolecules
• Avidin or protein-G with
positively charged tail conjugated
to negatively charged DHLA coat
of quantum dots
Goldman E.R. et al.( 2002 ) JACS,124 , 6378 – 82 ;
Analytical Chemistry , 74 , 841 – 7 .
Avidin
protein G
7. Quantum
dots v/s other fluorescent
probes
• Broader excitation spectrum and narrower gaussian
emission spectrum
• No spectral overlap between dots of different size – better
for multiplexing
Jaiswal & Simon 2004
9. Quantum dots for multiplexing
benign prostate
gland
Multiplex
Immunostaining
gland with a single
malignant cell
Malignant
HRS cells
To differentiate
Hodgkin’s from
non-Hodgkin’s
lymphoma
B cells
T cells
Liu J et al. Anal. Chem. 2010, 82, 6237–6243; Am. Chem. Soc. Nano 4:2755–65
10. Quantum dots v/s other fluorescent
probes
Photostability (quantum dots do not photobleach)
3T3 cells
Scale bar 10 µm.
Red: qdot 605 Conjugate
Green: Alexa488 Conjugate
Wu et al. Nat. Biotechnol. 2003;21(1):41-62
11. Quantum dots v/s other fluorescent probes
• Brighter than other fluorophores
Quantum dots
Fluorescein
Larson et al. 2003
12. Quantum dots and imaging
In vivo visualization of capillaries
Quantum dots
FITC-Dextran
Larson et al. 2003, Science 300:1434-1436
13. Quantum dots and imaging
anti-α-tubulin
antibody
anti-Her2
antibody
Cancer cell surface marker red & green Microfilaments
biotinylated
phalloidin
Actin filaments
Nuclear antigens
Wu et al. Nat. Biotechnol. 2003;21(1):41-62
14. Quantum dots and imaging
Glycine Receptors
Diffusion of single
Qdot-GlyRs in
synaptic boutons
Primary antibody ↔ secondary Antibody – biotin ↔ QD Streptavidin
Dahan et al. Science. 2003, 302:442-445
15. Quantum dots and imaging
EGF receptor
EGF-QD
Live imaging of receptor mediated endocytosis
Lidke et al. Nat. Biotechnol. 2004, 22:198
16. Quantum dots and imaging
1 µm
200 nm
200 nm
Single quantum dot crystals can be observed in electron micrographs
18. Quantum dots and imaging: FRET
• Quantum dots have been used in FRET
• In conjunction with Texas Red
• In conjunction with fluorescent quenchers
Willard et al. Nat Materials. 2003, 2:575
20. Advantages
•
•
•
•
Specific labeling of cells and tissues
Useful for long-term imaging
Useful for multi-color multiplexing
Suitable for dynamic imaging of
subcellular structures
• May be used for FRET-based analysis
21. Disadvantages
• Colloidal polymer-coated quantum dots can
aggregate irreversibly
• Toxic in vivo
• Quantum dots are bulkier than many organic
fluorophores
– Accessibility issues
– Mobility issues
• Cannot diffuse through cell membrane
– Use of invasive techniques may change physiology
25. Imaging techniques and related contrast agents
X-ray Iodinated contrast materials
Au
MRI Gadolinium-based
Fe-based
19
F-based
PET Radioactively labelled agents (11C, 18F)
26. X-ray CT
CT is ubiquitous in the clinical setting as. The increasing use
and development of micro-CT and hybrid systems that with PET,
MRI.
The most investigated NPs in this field are gold NPs, since they
have large absorption coefficients against the x-ray source used
for CT imaging and may increase the signal-to-noise ratio of the
technique.
To date, different types of gold NPs have been tested in a
preclinical setting as contrast agents for molecular imaging:
nanospheres, nanocages, nanorods and nanoshells. Gold NPs
formulations as an injectable imaging agent have been utilized to
study the distribution in rodent brain ex vivo
28. PET
The strategy utilized is consisting in incorporating PET emitters
within the components of the NP, or entrapping them within the
core.
brain cancer
Oku et al (2011), Int. J. Pharm. 403 :170–177
29. MRI
MRI relies upon the enhancement of local water proton relaxation in the
presence of a contrast agent (CA). CA are compounds that catalytically shorten
the relaxation times of bulk water protons.
T1 (longitudinal relaxation– in simple terms, the time taken for the protons to
realign with the external magnetic field) Positive CA (Gd)
T2 (transverse relaxation –in simple terms, the time taken for the protons to
exchange energy with other nuclei) Negative CA (Iron oxide agents )
30. Gd-based NP
several nanotechnological approaches have been devised, based on
2 ideas:
-carrying many Gd chelates;
-slow down the rotation of the complex
Examples include liposomes micelles dendrimers fullerenes.
However, this approach has not yet achieved clinical applications.
31. Magnetic Nanoparticles
magnetic NPs (MNPs) are of considerable interest because they
may behave either as contrast agents or carriers for drug
delivery. Among these, the most promising and developed NP
system is represented by superparamagnetic iron oxide agents
31
32. Types of Magnets
•
Ferromagnetic materials: the magnetic moments of
neighboring atoms align resulting in a net magnetic moment.
•
Paramagnetic materials are randomly oriented due to Brownian
motion, except in the presence of external magnetic field
.
• Superparamagnetic Combination of paramagnetic and ferromagnetic
properties. Made of nano-sized ferrous magnetic particles, but
affected by Brownian Motion. They will align in the presence of an
external magnetic field.
B
32
33. The most promising and developed NP system is
represented by superparamagnetic iron oxide
agents, consisting of a magnetite (Fe3O4) and/or
maghemite (Fe2O3) crystalline core surrounded by a
low molecular weight carbohydrate (usually
dextran or carboxydextran) or polymer coat.
Iron oxide NPs can be classified according to their
core structure, such as Monocrystalline (MION;
10–30 nm diameter), or according to their size as
ultra-small superparamagnetic (USPIO) (20–50 nm
diameter), superparamagnetic (SPIO) (60–250 nm).
36. Formation of Nanoparticles
• Solution of Dextran, FeCl3.6H2O and FeCl2.4H2O (acidic
solution)
–
Less Dextran Larger Particles
• Drip in Ammonium hydroxide (basic) at ~2oC
• Stirred at 75oC for 75 min.
• Purified by washing and
ultra-centrifugation
• Resulting Size ~ 10-20 nm
• Plasma half-life: 200 min
36
37. Variation of Formation
• Change Coating Material
• Crosslinking coating material
–
Increases plasma half-life
–
Same Particle Size
Lee H et al. J. AM. CHEM. SOC. 2007,129, 1273-12745
38. Magnetite Cationic Liposomes (MCL)
Fe3O4
• Why Cationic?
–
Interaction between + liposome and – cell
–
membrane results in 10x uptake.
39. Formation of MCL
• magnetite NP dispersed in distilled water
• N-(α-trimethyl-amminoacetyl)-didodecyl-D-glutamate
chloride (TMAG) Dilauroylphosphatidylcholine (DLPC)
Dioleoylphosphatidyl-ethanolamine (DOPE) added to
dispersion at ratio of 1:2:2
• Stirred and sonicated for 15 min
• pH raised to 7.4 by NaCl and Na phosphate buffered and
then sonicated
DLPC
DOPE
40. Uses of Nano Magnets
• Hyperthermia
– An oscillating magnetic field on nanomagnets result
in local heating by (1) hysteresis, (2) frictional losses
(3) Neel or Brown relaxation
41.
42. Cancer Treatment
• Heating due to magnetic field results in two possibilities
Death due to overheating
Increase in heat shock
proteins result in
anti-cancer immunity.
Ito A., Honda H., Kobayashi T. Cancer Immunol Immunother Res 2006 55; 320-328
42
43. Delivery Magnetic nanoparticles
• Magnetite nanoparticles
encapsulated in liposomes
– (1) Antibody conjugated
(AML)
– (2) Positive Surface Charge
(MCL)
• Sprague-Dawley rats injected with
two human tumors.
– Liposomes injected into 1
tumor (black) and applied
Alternating Magnetic Field
Ito A., Honda H., Kobayashi T. Cancer Immunol Immunother Res 2006 55; 320-328
43
45. Uses of Nano Magnets
• External Magnetic field for nanoparticle delivery
– Magnetic nanoparticles loaded with drug can be
directed to diseased site for Drug Delivery or MRI
imaging.
46. Magnetic Drug Delivery System
• Using Magnetic Nanoparticles for Drug
Delivery
• Widder & others developed method in late 1970s
• Drug loaded magnetic nanoparticles introduced through IV or IA
injection and directed with External Magnets
• Requires smaller dosage because of targeting, resulting in fewer side
effects
46
47. Magnetic Nanoparticles/Carriers
M
• Magnetite Core
• Starch Polymer Coating
M
M
M
• Bioavailable
• Phosphate in coating for functionalization
• Chemo Drug attached to Coating
M
Magnetite
Core
Starch Polymer
M
M
• Mitoxantrone
• Drug Delivered to Rabbit with Carcinoma
47
48. Results of Drug Delivery
• External magnetic
field (dark)
• deliver more
nanoparticles to tumor
• No magnetic field
(white)
• most nanoparticles in
non tumor regions
Alexiou C et al ANTICANCER RES 27: 2019-2022 (2007)
48
49. Magnetic nanoparticles in medicine
They consist of a metal or metallic oxide core, encapsulated in
an inorganic or a polymeric coating, that renders the particles
biocompatible, stable, and may serve as a support for
biomolecules.
• Drug or therapeutic radionuclide is bound to a magnetic NP,
introduced in the body, and then concentrated in the target area
by means of a magnetic field.
• Depending on the application, the particles release the drug or
give rise to a local effect (hyperthermia).
• Drug release can proceed by simple diffusion or take place
through mechanisms requiring enzymatic activity or changes in
physiological conditions (pH, osmolality, temperature, etc…).
50. Multifunctional Magnetic Nanoparticles
•
•
•
•
Magnetic nanocrystals as ultrasensitive MR contrast agents: MnFe2O4
Anticancer drugs as chemotherapeutic agents: doxorubicin, DOX
Amphiphilic block copolymers as stabilizers: PLGA-PEG
Antibodies to target cancer cells: anti-HER antibody (HER, herceptin)
conjugated by carboxyl group on the surface of the MMPNs
50
Yang, etal. Angew. Chem. 2007, 119, 8992 –8995.
51. Magnetic nanoparticles
The application of magnetic nanoparticles in cancer therapy is one
of the most successful biomedical exploitations of nanotechnology.
The efficacy of the particles in the treatment depends upon the
specific targeting capacity of the nanoparticles to the cancer cells.
Efficient, surface-engineered magnetic nanoparticles open up new
possibilities for their therapeutic potential.
… effective conjugation of folic acid on the surface of
superparamagnetic iron oxide nanoparticles (SPION) enables their
high intracellular uptake by cancer cells.
Such magnetic-folate conjugate nanoparticles are stable for a long
time over a wide biological pH range: additionally, such particles
show remarkably low phagocytosis as verified with peritoneal
macrophages.
52. Conclusions
• Nanomagnets can be made bioavailable by
liposomal encapsulation with targeting
• Nanoparticles smaller than 20 nm can be useful
for local heat generation
• Intracellular hyperthermia kills the cancer cell
and releases heat shock proteins. These are used
to target and kill other cancer cells.
• Results in reduction in growth of tumor size
• Nanomagnets can be used for MR Imaging in
52
vivo
53. MICROBUBBLES
• Used with ultrasound echocardiography and
magnetic resonance imaging (MRI)
• Diagnostic imaging - Traces blood flow and
outlines images
• Drug Delivery and Cancer Therapy
54. MICROBUBBLES
• Small (1-7 µm) bubbles of air (CO2, Helium) or
high molecular weight gases (perfluorocarbon).
• Enveloped by a shell (proteins, fatty acid esters).
• Exist - For a limited time only! 4 minutes-24
hours; gases diffuse into liquid medium after
use.
• Size varies according to Ideal Gas Law
(PV=nRT) and thickness of shell.
55. ultrasound
• Ultrasound uses high frequency sound
waves to image internal structures
• The wave reflects off different density
liquids and tissues at different rates and
magnitudes
• It is harmless, but not very accurate
56. Ultrasound and Microbubbles
• Air in microbubbles in the blood stream have almost 0
density and have a distinct reflection in ultrasound
• The bubbles must be able to fit through all capillaries and
remain stable
Soft Matter, 2008, 4, 2350–2359
Shell:protects the core from oxidation, prevents the leaching of highly toxic Cd 2+ions, improves the quantum yield and the fluorescence efficiency.
(A) Fluorescent capillaries containing
1 M QDs were clearly visible through the skin at the base of the dermis (100 m deep).
Excitation at 900 nm was delivered through a 20 0.95 NA water-immersion objective lens (40
mW out of the objective, average power at the focal plane unknown); the skin was stabilized by a
dorsal skin clamp. Blue pseudocolor is collagen imaged via its second harmonic signal at
450 nm. Dashed line indicates position of line scan shown in (D).
uspio COATING: it reduces the aggregation tendency of the uncoated particles, thus improving their dispersibility and colloidal stability; protects their surface from oxidation;
provides a surface for conjugation of drug molecules and targeting ligands; increases the blood circulation time by avoiding clearance by the reticuloendothelial system;
makes the particles biocompatible and minimizes nonspecific interactions, thus reducing toxicity;
Without coating, opsonin proteins deposit on Magnetite and mark them for removal by RES
Fe+2Fe2+3O4 = Fe3O4
DDS techniques to develop antibody-conjugated liposomes (immunoliposomes) containing magnetite nanoparticles (antibody-conjugated magnetoliposomes, AMLs). The targeting ability of AMLs mainly depends on the specificity of the antibody and the quantity and quality (including homogenous antigen expression) of the antigen on the tumor cell surface.
enhanced by conferring a positive surface charge to liposomes. We have developed ‘‘magnetite cationic liposomes’’ (MCLs) with improved adsorption and accumulation properties.
Unless tumor specific, damage can be done to all cells.
Intracellular hyperthermia is based on the principle that a magnetic particle can generate heat by hysteresis loss under an alternating magnetic field (AMF). In 1979, Gordon et al. A causa del fenomeno dell’isteresi magnetica, l’energia fornita al nucleo durante la fase di magnetizzazione non viene interamente restituita durante quella di smagnetizzazione, ma, ad ogni ciclo,
rimane immagazzinata nel nucleo. Poi si dissipa in calore
Schematic representation of Néel relaxation of nanoparticles, where the magnetic moment rotates within each particle and Brownian relaxation, where the particle rotates as a whole.
Widder and others developed magnetic micro- and nanoparticles to which cytotoxic drugs could be attached in late 1970s (1978).
The drug/carrier complex is then injected into the subject either via intravenous or intra-arterial injection.
High-gradient, external magnetic fields generated by rare earth permanent magnets (generally NdFeB, neodymium magnet, Neodymium, Iron & Boron) are used to guide and concentrate the drugs at target site (ie: tumor locations).
Once the magnetic carrier is concentrated at the tumor or other target in vivo, the therapeutic agent is then released from the magnetic carrier, either via enzymatic activity or through changes in physiological conditions such as pH, osmolality, or temperature, leading to increased uptake of the drug by the tumor cells at the target sites.
Core-shell structure:
Core = magnetic iron oxide (usually magnetite – [Fe3O4] or maghemite [gamma-Fe2O3])
Shell = generally a polymer such as silica, dextran, or PVA, or metals such as gold to which functional groups can be attached vis cross-linkers
Can be synthesized using both ionic and non-ionic surfactant techniques or encapsulated within a structure such as carbon cage or ferritin protein
Functionalized by attaching carboxyl groups, amines, biotin, streptavidin, antibodies, and others.
A number of groups have developed techniques for the synthesis of magnetoliposomes.
Core = magnetic iron oxide
Shell = artificial liposome
Generally used for magnetic hyperthermia (JAMES), but may be useful in drug delivery
More recently, gold/cobalt nanoparticles with core-shell structure and tailorable morphology have been synthesized in the size range of 5-25 nm
Produced via the rapid decomposition of organometallic precursors in the presence of surfactants that control the size and shape of the particles.
Major advantage = cobalt has a magnetic moment nearly twice that of magnetite or maghemite.
Another strategy for synthesis involves the precipitation of magnetic iron oxide nanoparticles within a porous polymer micro- or nanoparticle scaffold.
Advantage = possible to produce particles with a relatively tight size distribution and well-defined, spherical morphology.