3 research outputs found
Protein Microspheres with Unique Green and Red Autofluorescence for Noninvasively Tracking and Modeling Their in Vivo Biodegradation
Bovine
serum albumin (BSA) microspheres were prepared through a
facile and low-cost route including a high-speed dispersion of BSA
in cross-linking solution followed by spray drying. Interestingly
the as-prepared BSA microspheres possess unique blue-green, green,
green-yellow, and red fluorescence when excited by specific wavelengths
of laser or LED light. The studies of UV–visible reflectance
spectra and fluorescence emission spectra indicated that four classes
of fluorescent compounds are presumably formed during the fabrication
processes. The formation and the potential contributors for the unique
green and red autofluorescence were also discussed and proposed though
the exact structures of the fluorophores formed remain elusive due
to the complexity of the protein system. The effect of spray-drying
conditions on the morphology of spray-dried samples was investigated
and optimized. FTIR was further employed to characterize the formation
of the functional groups in the as-prepared autofluorescent microspheres.
Good in vitro and in vivo biocompatibility was demonstrated by the
cytotoxicity test on the A549 cancer cells and tissue histological
analysis, respectively. The autofluorescent BSA microspheres themselves
were then applied as a novel tracer for convenient tracking/modeling
of the biodegradation of autofluorescent BSA microspheres injected
into mouse model based on noninvasive, time-dependent fluorescence
images of the mice, in which experimental data are in good agreement
with the proposed mathematical model. All these studies indicate that
the as-developed protein microspheres exhibiting good biocompatibility,
biodegradability, and unique autofluorescence, can significantly broaden
biomedical applications of fluorescent protein particles
Fluorescent, Bioactive Protein Nanoparticles (Prodots) for Rapid, Improved Cellular Uptake
A simple and effective method for
synthesizing highly fluorescent,
protein-based nanoparticles (Prodots) and their facile uptake into
the cytoplasm of cells is described here. Prodots made from bovine
serum albumin (nBSA), glucose oxidase (nGO), horseradish peroxidase
(nHRP), catalase (nCatalase), and lipase (nLipase) were found to be
15–50 nm wide and have been characterized by gel electrophoresis,
transmission electron microscopy (TEM), circular dichroism (CD), fluorescence
spectroscopy, dynamic light scattering (DLS), and optical microscopic
methods. Data showed that the secondary structure of the protein in
Prodots is retained to a significant extent and specific activities
of nGO, nHRP, nCatalase, and nLipase were 80%, 70%, 65%, and 50% of
their respective unmodified enzyme activities. Calorimetric studies
indicated that the denaturation temperatures of nGO and nBSA increased
while those of other Prodots remained nearly unchanged, and accelerated
storage half-lives of Prodots at 60 °C increased by 4- to 8-fold.
Exposure of nGO and nBSA+ nGO to cells indicated rapid uptake within
1–3 h, accompanied by significant blebbing of the plasma membrane,
but no uptake has been noted in the absence of nGO. The presence of
nGO/glucose in the media facilitated the uptake, and hydrogen peroxide
induced membrane permeability could be responsible for this rapid
uptake of Prodots. In control studies, FITC alone did not enter the
cell, BSA-FITC was not internalized even in the presence of nGO, and
there has been no uptake of nBSA-FITC in the absence of nGO. These
are the very first examples of very rapid cellular uptake of fluorescent
nanoparticles into cells, particularly nanoparticles made from pure
proteins. The current approach is a simple and efficient method for
the preparation of bioactive, fluorescent protein nanoparticles of
controllable size for cellular imaging, and cell uptake is under the
control of two separate chemical triggers
Long Circulating Self-Assembled Nanoparticles from Cholesterol-Containing Brush-Like Block Copolymers for Improved Drug Delivery to Tumors
Amphiphilic
brush-like block copolymers composed of polynorbonene-cholesterol/polyÂ(ethylene
glycol) (PÂ(NBCh9-<i>b</i>-NBPEG)) self-assembled to form
a long circulating nanostructure capable of encapsulating the anticancer
drug doxorubicin (DOX) with high drug loading (22.1% w/w). The release
of DOX from the DOX-loaded PÂ(NBCh9-<i>b</i>-NBPEG) nanoparticles
(DOX-NPs) was steady at less than 2% per day in PBS. DOX-NPs were
effectively internalized by human cervical cancer cells (HeLa) and
showed dose-dependent cytotoxicity, whereas blank nanoparticles were
noncytotoxic. The DOX-NPs demonstrated a superior <i>in vivo</i> circulation time relative to that of free DOX. Tissue distribution
and <i>in vivo</i> imaging studies showed that DOX-NPs preferentially
accumulated in tumor tissue with markedly reduced accumulation in
the heart and other vital organs. The DOX-NPs greatly improved survival
and significantly inhibited tumor growth in tumor-bearing SCID mice
compared to that for the untreated and free DOX-treated groups. The
results indicated that self-assembled PÂ(NBCh9-<i>b</i>-NBPEG)
may be a useful carrier for improving tumor delivery of hydrophobic
anticancer drugs