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Silk sericin and its applications: A review



Silk consists of two types of proteins, silk fibroin and sericin. Sericin contributes about 20-30 per cent of total cocoon weight. It is characterized by its high content of serine and 18 amino acids, including essential amino acids. There are different methods of isolation of sericin from silk thread. Solubility, molecular weight, and gelling properties of sericin depend on the method of isolation. It has wide applications in pharmaceuticals and cosmetics such as, wound healing, bioadhesive moisturizing, antiwrinkle and antiaging.
Journal of Scientific & Industrial Research
Vol. 63, April 2004, pp 323-329
Silk sericin and its applications: A review
M N Padamwar and A P Pawar*
Department of Pharmaceutics, Bharati Vidyapeeth Deemed University, Poona College of Pharmacy, Erandwane,
Pune 411 038
Silk consists of two types of proteins, silk fibroin and sericin. Sericin contributes about 20-30 per cent of total cocoon
weight. It is characterized by its high content of serine and 18 amino acids, including essential amino acids. There are
different methods of isolation of sericin from silk thread. Solubility, molecular weight, and gelling properties of sericin
depend on the method of isolation. It has wide applications in pharmaceuticals and cosmetics such as, wound healing,
bioadhesive moisturizing, antiwrinkle and antiaging.
Keywords: Silk, Silk proteins, Sericin, Isolation
IPC: Int. Cl.7: D 01 B 7/00, D 01 C 3/02, A 61 P
Sericulture in India
Silk has been a scientific curiosity for centuries
and a new insight about these polymers are surfacing
with improved analytical methods and the tools of
molecular biology. Silk includes a broad range of
primarily protein-based high molecular weight
polymers often associated with insects, silkworm, and
orb weaving spiders1. Sericulture, in India, is
essentially a cottage industry. The post rearing
operations are fairly cost-effective and silkworm
rearing is still only considered as a side activity to the
main farm activity. India is the second largest
producer of silk in the world and has the distinction
of producing all the four varieties of silk. Presently,
India produces nearly 16,700 mt silk/y and reeled silk
prices are in the range of Rs 900-1300/kg, the pierced
cocoons and wastesilk generated at the rearing are
sold at Rs 80-100/kg. This waste contributes nearly
30 per cent of total cocoon production2,3. Wastesilk
can be classified as waste from the cocoon, rearing
waste, and thread waste. Silk wastes can be used as
coarse yarn and spun silk, which can be incorporated
in natural rubber to achieve the physicochemical
properties4. It is also possible to utilize the silk waste
by extracting fibroin and sericin from silk polymer,
which helps to make sericulture a viable agro
Structure of Silk
Silk is a continuous strand of two-filaments
cemented together forming the cocoon of silkworm,
Bombyx mori. Silk filament is a double strand of
fibroin, which is held together by a gummy substance
called silk sericin or silk gum. Silk fibroin is the
protein that forms the filament of silkworm and gives
its unique physical and chemical properties4,5. Silk
adapts various secondary structures, including α-
helix, β-sheet, and crossed β-sheet6.
Fibroin is a glycoprotein composed of two
equimolar protein subunits of 370 and 25 kDa
covalently linked by disulphide bonds. Fibroin
filament is made of both crystalline and amorphous
domains. The amorphous domains are characterized
by the presence of amino acids with bulkier side
chains, whereas the crystalline domains are
characterized by high percentage of alanine, glycine,
and serine (12, 30, 44 per cent, respectively), which
contains short side chains to permit the close packing
densities for overlying sheets7. The β-sheet form (silk
II or β-silk) and crystalline form (silk I) have been
reported for silk fibroin, having relative molecular
masses of 350 – 415K (refs 3,8).
Anti-parallel β-sheet structure forming microfibrils
is responsible for the crystalline nature of the silk
fibre. The microfibrils are organized into fibril
bundles, with several bundles leading finally to a
single silk thread7.
*Ph. No: 91-20-5437237
Fax No: 91-20-5439383
Sericin is a second type of silk protein, which
contains 18 amino acids including essential amino
acids and is characterized by the presence of 32 per
cent of serine. The total amount of hydroxy amino
acids in sericin is 45.8 per cent. There are 42.3 per
cent of polar amino acid and 12.2 per cent of
nonpolar amino acid residues. Sericin contributes
about 20-30 per cent of total cocoon weight. Their
main role is to envelop the fibroin. In presence of
sericin the fibres are hard and tough and become soft
and lustrous after its removal. Sericin occurs mainly
in an amorphous random coil and to a lesser extent, in
a β-sheet organized structure. The randomly coiled
structure easily changes to β-sheet structure, as a
consequence of repeated moisture absorption and
mechanical stretching7,9.
Forms of Silk Sericin
Sericin can be classified into three fractions,
depending on their solubility as sericin A, sericin B,
and sericin C. Sericin A is the outermost layer and
insoluble in hot water. It contains about 17.2 per cent
of nitrogen and amino acids like, serine, threonine,
glycine, and aspartic acid. Sericin B is the middle
layer and on acid hydrolysis it yields amino acid of
sericin A, in addition to tryptophan. It contains 16.8
per cent of nitrogen. Sericin C is the innermost layer,
which is adjacent to fibroin and is insoluble in hot
water and can be removed from fibroin by treatment
with hot dilute acid or alkali. On acid hydrolysis it
yields proline in addition to amino acids of sericin B.
It also contains sulphur and 16.6 per cent of nitrogen
9,10. Sericin has been divided into various species
based on relative solubilities. Various fractions of
sericin are also designated by other researchers
depending on their dissolution behaviour as sericin A
and B, or sericin I, II, III, and IV, or S1, S2, S3, S4,
and S5, and as α, β, and γ modification6,7. The major
molecular conformation of easily soluble sericin is
random coil, whereas the β-sheet structure is more
difficult to dissolve. The repeated moisture
absorption makes molecular aggregation structure
denser and forms more crystalline structure, which is
having reduced solubility.
The γ-ray study shows the three layers in the
sericin structure. The outer layer contained some fibre
direction filaments, middle layer exhibits cross-fibre
direction filaments, and the inner layer shows
longitudinal filaments11. The structure of sericin also
depends on the casting temperature. Lower the
casting temperature more the sericin molecules
assume β-sheet structure rather than random coil12,13.
Properties of Silk Sericin
Gelling Property
Sericin contains random coil and β-sheet structure.
Random coil structure is soluble in hot water and as
the temperature lowers the random coil structure
converts to β-sheet structure, which results in gel
formation14, 15.
Sol-Gel Transition
Sericin has sol-gel property as it easily dissolves
into water at 50-60oC and again returns to gel on
Isoelectric pH
As there are more acidic than basic amino acid
residues the isoelectric point of sericin is about 4.0
(ref. 7).
Solubility of Sericin
Solubility of sericin in water decreases when the
sericin molecules are transformed from random coil
into the β sheet structure. The solubility of sericin
increases by addition of poly (Na acrylate) and
decreases by the addition of polyacrylamide,
formaldehyde, or resin finishing agents17-19.
Molecular Weight
Extracting sericin using 1 per cent sodium
deoxycholate solution followed by precipitation,
using equal volume of 10 per cent trichloroacetic
acid, shows molecular weight in the range of 17100 to
18460 (ref. 20).
Extraction of sericin by hot water shows molecular
weight of 24000 by gel electrophoresis, whereas
spray-drying method produced sericin of molecular
weight 5000-50,000, with enzyme action 300-10,000
and 50,000 when it is extracted with aqueous urea at
100ºC (ref. 21).
Isolation of Silk Sericin
Isolation with Aid of Heat
The removal of gum from crude silk is based
entirely upon its solubility in hot water. The number
of methods illustrated by researchers for removing
gum are as follows:
The removal of gum by dilute solution of
sodium carbonate.
Hot water extraction of raw silk, followed by
evaporation to obtain powder.
Boiling of the crude silk in water and renewing
the water until the extract no longer gives a
precipitate with gallic acid.
Three successive 1 h extractions of silk or
simply heating in water at 100ºC or autoclaving
at 118°C or autoclaving for 3 h under 2.5-3
atmosphere pressure.
Sericin with average molecular weight of 50,000
extracted with aqueous solution of urea at 100ºC
from cocoons21.
Using water at 50-60ºC for 25 d to avoid the
Silk fibres can be completely degummed in
boiling solutions of pH 11 containing 5-6 per
cent bentonite23.
In a series of experiments, it is demonstrated that
most of the sericin is removed by autoclaving for one
and half hour under pressure of 600-700 mm Hg (14
lb), whereas increasing the time of treatment to 2 h
causes no greater loss in weight of fibres. It is also
observed that the extracting sericin at low pressure
(25 cm Hg, 5 lb) shows good results.
When sericin is extracted from cocoons of Bombyx
mori by heating on water bath and autoclaving at
different temperatures the satisfactory yield is
obtained by autoclaving at 105°C for 30 min with
good gelling property and yield. Further increase in
temperature increases the yield but looses its gelling
Extraction of Silk Sericin using Enzymes
Extraction is carried out by using enzyme
alkylase25 or with 2-2.5g/L alkaline protease at 60°C
for 90 min, at pH 10 (ref. 26).
Hydrolysis with trypsin at different concentrations,
temperatures and treatment times is employed for
extraction of sericin. For 1 per cent of trypsin
solution the hydrolysis is almost complete in 10 and
32 h at 37 and 20°C, respectively. The amount of
sericin obtained by 4 h treatment with 1 and 8 per
cent of trypsin solution is 26.4 and 28.7 per cent,
Precipitation of Silk Sericin from Aqueous Solution
Several methods22 proposed for precipitations of
sericin from its aqueous solution are as follows:
Precipitation of sericin with lead acetate from
aqueous solution, which is decomposed by
hydrogen sulphide and the protein is separated
by alcohol.
Evaporation of sericin solution and dissolution
of obtained residue in alkali followed by
precipitation by alcohol.
Precipitation of sericin from aqueous extract by
acetic acid and then treating the precipitate with
alcohol and ether.
According to Shelton and Johnson22 the method
of recovery by evaporation to dryness is least
satisfactory. Protein molecule on continuous
boiling of the aqueous solution in an open kettle
loses its capacity to form gel. A method in
which hot concentrated sericin solution is
poured directly from the autoclave into 7 to 8
vol of 95 per cent alcohol is found to be
satisfactory. The clear supernatant liquor is
separated from the precipitate and the
precipitate is washed with 95 per cent alcohol.
The obtained cake is dried slowly over calcium
chloride in a desiccator to get white and easily
pulverized powder.
Salting out of sericin solution by addition of
15 g solid ammonium sulphate to each 100 mL
of solution results in gelatinous precipitate,
which does not support bacterial growth.
Hamaoka et al.28 have extracted silk with
hexane to remove oils and fats and by heating in
water at 120°C for 30 min. After freeze thawing
the sericin deposited in thawing is washed with
hydrophilic organic solvent and the powdered
sericin is recovered.
Applications of Silk Sericin
Silk sericin due to its proteinous nature is
susceptible to the action of proteolytic enzymes
present in body and hence it is digestible. This
property makes it a biocompatible and biodegradable
material. Because of some additional properties like,
gelling ability, moisture retention capacity, and skin
adhesion. it has wide applications in medical,
pharmaceutical, and cosmetics.
Medical and Pharmaceutical Applications
Sericin is soluble in hot water and as the time
precedes it converts into gel. Jun et al.29 have found
that conversion of α-random coil to β-sheet structure
gives gel. One per cent aqueous sericin solution
produces gel at pH 6-7 at room temperature and
gelation speed increases as the concentration of
sericin increases30-32. The aqueous sericin solution
containing 1.5 and 2 per cent w/w of sericin obtained
by autoclaving at 105°C for 30 min does not show
good gelling. Sericin gel in the presence of glycerin,
propylene glycol, and tween-80 shows synerisis,
whereas sericin with pluronic and carbopol gives
stable gels. In the presence of pluronic sericin gel it
shows concentration dependance24. Kewon et al.33
have shown the effect of concentration of pluronic
and temperature on the gel property of sericin. The
gelling of sericin is accelerated with increase in
temperature and with increase in poloxamer
concentration, whereas the sol-gel transition of
sericin becomes irreversible. Blends of polyvinyl
alcohol and sericin are cross-linked to give hydrogels.
Hydrogels with good mechanical strength and water
resistance are produced by casting aqueous solution
containing sericin and dimethyl urea on a glass plate
and heating at 80 and 120°C for 1 and 3 h,
Sericin gives a very stable emulsion when shaken
with water immiscible liquid22,35. The sericin protein
is also used as horizontal alignment film for the liquid
crystal to achieve uniform optical properties and to
increase the stability of product36.
Fibroin and sericin, when sulphonated show anti-
thrombotic effect37. One stage condensation of
salicylic acid, formaldehyde, and sericin creates a co-
polymer with a molecular mass of 6000-8000 Da. A
concentration of 0.01-1 mg/mL in blood exhibits anti-
coagulant, fibrinolytic, and anti-aggregation activity
towards thrombocytes at 0.5 mg/mL (ref. 38). Sericin
with molecular weight of 1,00,000 shows an
inhibitory action for tyrosinase and lipid per
oxidation with rat brain homogenates39,40. The
addition of 0.1-2 mg/mL of sericin into the aqueous
solution shows heat resistant DNA polymerase
activity41. Sericin has been found to possess wound-
healing property and can be used as wound healing
covering material in the form of film42. Sericin also
has adhesive property due to its chemical
composition. It has affinity to keratin7. Silk threads
obtained from mulberry silkworm can be used for
making surgical sutures43. Silk sericin membranes are
good bandage materials and the film has adequate
flexibility and tensile strength. Due to its good
biocompatibility and infection resistant nature, it is a
novel wound coagulant material. Additionally, its
flexibility and water absorption properties promote
smooth cure for defects in the skin and do not cause
any peeling of the skin under regeneration when
detached from the skin44.
Kurioka45 has explained silk sericin as a
biomaterial. The silk sericin has the potential to find
application in the development of contact lenses. The
graft polymers are prepared with methyl methacrylate
or styrene and are also biocompatible46,47.
Intake of sericin containing food relives
constipation, suppresses development of bowel
cancer and accelerates the absorption of minerals. In
rats, consumption of sericin elevates the apparent
absorption of zinc, iron, magnesium, and calcium by
41, 41, 21, and 17 per cent, respectively48. A dietary
supplementation of 4 per cent of sericin suppresses
induced constipation in rats because of its low
digestibility along with water holding capacity49.
Sericin, when given orally, causes a dose dependent
decrease in the development of colonic aberrant crypt
foci. The incidence and the number of colon tumours
are suppressed by consumption of sericin. Sericin
have anti-tumor activity50-52.
Oxygen permeable membranes are made up of
fibroin and sericin with 10-16 per cent water and are
used for contact lenses, and as artificial skin53. Agar
and/or compounds containing agarose and sericin are
mixed with water to form sheet shaped gels and
which when dried at 0-40°C under load of 0.01-2
kg/cm2 give the polymer membranes54.
Cosmetic Applications
In addition to above-mentioned medical and
pharmaceutical uses of sericin, it has been used as
component of cosmetics. Sericin alone or in
combination with silk fibroin has been used in skin,
hair, and nail cosmetics. Sericin when used in the
form of lotion, cream and ointment shows increased
skin elasticity, antiwrinkle, and antiaging effects7,55-57.
Padamwar et al.58 have shown the moisturizing
property of the sericin gel, evaluated by
hydroxyproline assay, impedance measurement,
trance epidermal water loss (TEWL), and scanning
electron microscopy (SEM). Sericin gels increase the
hydroxyproline content in stratum corneum and
decrease skin impedance, which reveals moisturizing
property of sericin. Sericin gels with pluronic and
carbopol, act as moisturizer by repairing natural
moisturizing factor (NMF) as well as prevent TEWL
by preventing water loss from the skin. SEM has
shown the decrease cracking and flaking as compare
to dry skin and normal skin replicas.
Powder containing 5-30 per cent sericin with
average molecular weight 7,000-3,00,000 and 70-95
per cent silk fibroin when applied as film shows
antistaticity and moisture absorbability59. Sericin
hydrolysate solution shows that dermatitis is
controlled60. Sweat and sebum absorbing type of
cosmetics containing cellulose fibres impregnated
with fibroin dispersion and aqueous sericin solution
are also reported61. Lotion containing 1 per cent w/w
sericin and 4 per cent w/w D-glucose shows
moisturizing and conditioning effect62. Creams
containing 0.001-30 per cent w/w of sericin have
improved cleansing properties with less skin
irritation63. Sericin powder in the form of sericin
hydrolysate coated talc, mica, titania, iron oxide, and
nylon have been used to formulate foundation cream
and eyeliners64. The microcapsules or nanocapsules
consisting of polysiloxane gel, UV absorbent core
and UV scattering agent, silicone treated mica, silicon
treated titanium dioxide, silicon treated iron oxides,
squalene, glycerin trioctanoate, and talc have resulted
in cosmetic foundation having a SPF value of 25.7.
Sericin in sunscreen composition enhances the light
screening effect of UV filter like triazines, and
cinnamic acids ester65.
Nail cosmetics, containing 0.02-20 per cent sericin
are reported to prevent nail from chapping,
brittleness, and imparting the inherent gross to nails66.
Hair and bath preparations, containing 0.02-2 per cent
sericin and 0.01-1 per cent olive oil, fatty acid or their
salts show reducing damage of hair surface by
binding of sericin to hairs67. Sericin hydrolysates with
average molecular weight 300-3000 are used as
conditioners for skin and hair68. Shampoo containing
sericin and pelarogenic acid of pH less than six are
useful for the care and cleaning of hairs69.
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... There are several methods for separating sericin from silk. The separation procedure affected the solubility, molecular weight, and gelling characteristics of sericin [3,4]. Sericin has been studied for a variety of potential uses due to its remarkable biochemical and biophysical characteristics. ...
... Sericin properties such as biocompatibility, biodegradability, and wettability have been employed in skin, hair, and nail cosmetics alone or in conjunction with silk fibroin. Sericin, when utilized in lotions, creams, and ointments, demonstrates a raised skin elasticity, anti-wrinkle, and anti-aging impacts [4,52]. Moisturizers have been developed especially; they are mostly applied for preventing and postponing the dehydration of the skin's top layer [53]. ...
... Recently, polymers, nanoparticles, lipidic carriers, micelles [62], natural proteins [4], and other pharmaceutical carriers also received more attention. Silk sericin-based drug delivery systems are attracting attention among different naturally occurring molecules as admirable vehicles capable of releasing their active content at a particular location and rate in the body [4,[63][64][65]. ...
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Silk has turned into valuable biological material for a wide range of research applications. Sericin in silk can be utilized as a final material for natural or handmade fibers in the textile, cosmetics, and hygiene industries because of its various biological characteristics such as antibacterial, antioxidant, anti-tumor action, UV resistance, and absorbency. Sericin is disposed of annually as sewage in silk industries, according to findings on silk sericin and its application in industry. If sericin is recycled and recovered, it will have significant economic advantages in addition to reducing pollution. Since researches on the utilization of waste produced in the silk industry and the development of mechanical properties for use in many industries have not been performed simultaneously, a gap in this field has remained. The main aim of this review was to investigate sericin recycling in the silk industry while also improving mechanical properties for various applications in the industry. Sericin has a variety of biochemical and biological characteristics, according to past works. However, its mechanical characteristics are poor. There are a few ways to improve mechanical characteristics, the best of which is to increase sericin molecular weight. Better performance could be achieved by enhancing mechanical characteristics for application in various industries such as medical and cosmetics. New methods for obtaining high-value-added products have also been developed to provide environmental, social, and economic advantages. Hence, this review aims to explore some of the uses of sericin in different industries. Moreover, one of the most significant drawbacks of sericin forms is their poor mechanical properties. In addition, the present review considers the solutions of improvement for the mechanical characteristics of sericin.
... Cosmetic industry: Sericin's properties such as biocompatibility, biodegradability and wettability allow the development of cosmetic products for skin, nails and hair (Padamwar & Pawar, 2004;Voegeli et al., 1993). Sericin used in the form of moisturizers is mainly utilized to prevent and delay the dehydration of the top layer of the skin. ...
... This enzyme catalyzes the tyrosinase oxidation, which is the amino acid responsible for the skin melanin biosynthesis, and the enzymatic browning in foods (Norihisa et al., 1998). According to Padamwar & Pawar (2004), sericin has a synergic effect during the intestinal absorption of minerals such as iron, zinc, magnesium and calcium. It helps to modular both fermentation and barrier processes (Okazaki et al., 2011). ...
... Cosmetic industry: Sericin's properties such as biocompatibility, biodegradability and wettability allow the development of cosmetic products for skin, nails and hair (Padamwar & Pawar, 2004;Voegeli et al., 1993). Sericin used in the form of moisturizers is mainly utilized to prevent and delay the dehydration of the top layer of the skin. ...
... This enzyme catalyzes the tyrosinase oxidation, which is the amino acid responsible for the skin melanin biosynthesis, and the enzymatic browning in foods (Norihisa et al., 1998). According to Padamwar & Pawar (2004), sericin has a synergic effect during the intestinal absorption of minerals such as iron, zinc, magnesium and calcium. It helps to modular both fermentation and barrier processes (Okazaki et al., 2011). ...
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Foliar feeding is a technique of feeding plants by applying liquid fertilizers directly to their leaves. Plants are able to absorb materials that are essential through their leaves. The absorption takes place through their epidermis. The application of fertilizers to foliage of crop as spray solution is known as foliar spray. This method is suitable for application of small quantities of fertilizers, especially micro nutrients. Foliar application is not a substitute for soil application but only a supplement to it.
... The protein's core portion is mostly hydrophobic, but the nonrepetitive amino-and carboxy-terminal regions are more hydrophilic [22]. The firm threads are indicative of well-oriented β-sheet, the main secondary structure in silk fibres [23][24][25]. The first Raman spectrum of B. mori silk fibre has clearly shown the predominance of βsheet, matching the results previously obtained from other techniques [26]. ...
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The silkworm, Bombyx mori, produces sericin that surrounds and holds together the two fibroin filaments that make up the thread of the cocoon. A major advantage of reusing sericin that would otherwise be discarded by the textile industry is that it considerably decreases environmental issues and has a high scientific and commercial value.. The molecule's physicochemical properties are crucial in numerous biomedical applications. Sericin's molecular weight and amino acid concentration vary depending on the method used to extract the molecule and the silkworm's ancestry. Food and cosmetics can benefit from the antioxidant and hydrophobic amino acids included in sericin. In addition, sericin is plausibly used for wound healing, cell proliferation, protection from the harmful effects of sunlight and formulation of lotions and shampoos and moisturising agents. Low digestibility of sericin, together with the antioxidant properties, increases the use in the medical sector, such as the treatment of cancer, antibiotic, and anti-inflammatory agent.Computational studies on structural identification of sericin led to determine its functional activities.Additionally, sericin can be used for tissue engineering, cryopreservation, and cell growth, as well as a useful cryoprotectant.
... Removing sericin from silk can be accomplished in a variety of ways. High-temperature, whether or not combined with high pressure by autoclaving; acidic, primarily citric acid solution; alkali, using sodium carbonate solution; and urea [4], [ 5]. The separation technique affected sericin's solubility, molecular weight, and gelling properties [6]. ...
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Because of its adequate biological and mechanical properties, sericin has been considered for different applications. Sericin is found to have anti-tumoral properties against colon cancer, mechanical properties, as well as anticoagulant and cryoprotective properties. According to these findings, sericin is a significant component of the health industry. Silk sericin exhibits biodegradability, non-toxicity, oxidation resistance, UV resistance, and moisturizing characteristics. The present review is mainly focused on considering the mechanical and biological characteristics of silk sericin, as well as its applications in many industries, especially in the medical industry. In addition, one of the most notable limitations of sericin forms in many application fields is their lack of mechanical properties. Better crystallinity and a longer molecular chain result in improved mechanical properties. Additionally, mechanical properties are influenced by the macromolecular structure, notably porosity. The textile silk procedure has the ability to influence the features of sericin samples, such as thermal stability and structure. Therefore, the present study reviews the past works on the improvement solutions of the mechanical characteristics of sericin.
... After that, the samples were placed in PBS for 24 h. At determined intervals of time (0. 5,1,2,4,8,12,16,20, and 24 h), the samples were taken, and their wet weight (Ww) was measured by placing them on filter paper for about 10 min to entrap moisture present in the nanofibers' pores, then they were weighed [22]. The average swelling index was calculated by using the following equation: ...
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Diabetic foot ulceration is the most distressing complication of diabetes having no standard therapy. Nanofibers are an emerging and versatile nanotechnology-based drug-delivery system with unique wound-healing properties. This study aimed to prepare and evaluate silk-sericin based hybrid nanofibrous mats for diabetic foot ulcer. The nanofibrous mats were prepared by electro-spinning using silk sericin mixed with different proportions of polycaprolactone (PCL) and cellulose acetate (CA) loaded with ferulic acid (FA). The in vitro characterizations, such as surface morphology, mechanical properties, swelling behaviour, biodegradability, scanning electron microscopy, and drug release were carried out. The SEM images indicated that nanofibers formed with varied diameters, ranging from 100 to 250 nm, and their tensile strength was found to range from 7 to 15 MPa. In vitro release demonstrated that the nanofibers sustained FA release over an extended time of period. In vitro cytotoxicity showed that the nanofibers possessed a lower cytotoxicity in HaCaT cells. The in vivo wound-healing studies demonstrated an excellent wound-healing efficiency of the nanofibers in diabetic rats. Furthermore, the histopathological studies showed the nanofibers ability to restore the skin's normal structure. Therefore, it was concluded that the prepared silk-sericin-based hybrid nanofibers loaded with FA could be a promising drug-delivery platform for the effective treatment of diabetic foot ulcers.
... composites with other polymers or biomaterials have been used as adhesives or conductive inks for the fabrication of devices but are quite few in number. Cosmetics and the pharmaceutical industries have also opened new frontiers for sericin because of its wound healing, skin adhesion, and moisture retention capacity (Padamwar & Pawar, 2004). These research have significantly reduced sericin's wastage, thereby preventing environmental contamination that occurs due to the high oxygen demand required for degradation of sericin in nature and finding ways to make it a value-added product (Aramwit et al., 2012). ...
Silk is a fibrous protein, has been a part of human lives for centuries and was used as suture and textile material. Silk is mainly produced by members of certain arthropods such as spiders, butterflies, mites, and moths. However, recent technological advances have revolutionized silk as a biomaterial for various applications ranging from heat sensors to robust fibers. The biocompatibility, mechanical resilience, and biodegradability of the material make it a suitable candidate for biomaterials. Silk can also be easily converted into several morphological forms, including fibers, films, sponges, and hydrogels. Provided these abilities, silk have received excellent traction from scientists worldwide for various developments, one of them being its use as a bio-sensor. The diversity of silk materials offers various options, giving scientists the freedom to choose from and personalize them as per their needs. In this review, we foremost look upon the composition, production, properties, and various morphologies of silk. The numerous applications of silk and its derivatives for fabricating biosensors to detect small molecules, macromolecules, and cells have been explored comprehensively. Also, the data from various globally developed sensors using silk have been described into organized tables for each category of molecules, along with their important analytical details. This article is protected by copyright. All rights reserved.
... Fibroin, representing approximately 75% of the weight of the cocoon, is a linear, water-insoluble protein with high tensile strength. On the other hand, sericin represents approximately 25% of the cocoon weight, it is a globular, water-soluble protein whose function is to keep the fibroin fibers together [24]. Silk fibroin is made up of three components, a heavy chain (391 kDa) and a light chain (26 kDa) linked by a disulfide bridge, and a glycoprotein, P25 (25-30 kDa) in a 6: 6: 1 molar ratio to yield a 6.3 MDa megastructure [25]. ...
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The use of nanoparticles in biomedical fields is a very promising scientific area and has aroused the interest of researchers in the search for new biodegradable, biocompatible and non-toxic materials. This chapter is based on the features of the biopolymer silk fibroin and its applications in nanomedicine. Silk fibroin, obtained from the Bombyx mori silkworm, is a natural polymeric biomaterial whose main features are its amphiphilic chemistry, biocompatibility, biodegradability, excellent mechanical properties in various material formats, and processing flexibility. All of these properties make silk fibroin a useful candidate to act as nanocarrier. In this chapter, the structure of silk fibroin, its biocompatibility and degradability are reviewed. In addition, an intensive review on the silk fibroin nanoparticle synthesis methods is also presented. Finally, the application of the silk fibroin nanoparticles for drug delivery acting as nanocarriers is detailed.
Sericin, a silk-derived non-immunogenic protein, has been used to improve cell culture performance by increasing viability, cell concentration, and promoting adherence of several cell lines. Here, we hypothesized that the properties of sericin can enhance the amplification of flaviviruses in cell cultures. The propagation of flavivirus is inefficient and limits scientific research. Zika virus (ZIKV) is an important human pathogen that has been widely studied because of its high impact on public health. There is a need to amplify Zika virus both for research and vaccine development. In this work, we show that sericin improves ZIKV amplification in insect (C6/36) and mammalian (VeroE6) cell cultures, and that it has a cryoprotectant capacity. Supplementation of cell culture media with sericin at 80 µg/mL resulted in a significant increase of 1 log in the concentration of ZIKV infectious particles produced from both cell lines. Furthermore, final virus yields increased between 5 to 10-fold in Vero cells and between 7 to 23-fold in C6/36 cells when sericin was supplemented, compared to control conditions. These results show that sericin is an effective supplement to increase ZIKV production by Vero and C6/36 cells. Additionally, sericin was a suitable cryoprotective agent, and hence an alternative to FBS and DMSO, for the cryopreservation of C6/36 cells but not for Vero cells.
A wound dressing material comprises an amorphous film having a crystallinity of less than 10% and containing fibroin and sericin as the main components.
The structure of sericin is related to the stripping resistance of cocoon filaments. When it was strong, the thermal absorption peak of DSC curve for sericin appeared at higher temperature region, indicating that both beta-structure and random coil structure were present in sericin. On the other hand, when the stripping resistance was weark, sericin had only the random coil structure. The adhesive strength of sericin closely depended on the phase of sericin, being strong when the sericin molecule in solution transformed from the random coil to the beta-structure.
This review covers literature dealing with the regeneration of silk polymer from silk fibre. The silk fibre used is that could not be used in the production of continuous thread, and waste collected during processing. The subjects covered include the classification of waste silk, separation of the polymer from the waste, properties of silk fibroil powder, the formation and properties of thin films and applications in fibres, films and membranes.
Gelation time decreased with rising temperature and increasing sericin concentration. - Chemical Abstracts, 111(4), 1989, abstract 24823
The molecular basis of sol-gel transformation of sericin extracted from cocoons with hot water was investigated by analyzing circular dichroism, infrared spectrum and X-ray analyses of sericin gels during the transformation. Results showed that sericin gel was reversible; it easily dissolved into sol at high temperatures and again returned to gel by cooling. This property was in contrast to the that of fibroin gel which was irreversible and did not become sol by heating. These difference between fibroin and sericin gels may mirror their structural divergence, which may be ascribed to their difference in β-structure, contents of polar amino acids (Ser, Thr, Asp) and mobility of moleules. © 1996, The Japanese Society of Sericultural Science. All rights reserved.
Silk consist of two types of proteins, silk fibroin and silk sericin. Fibroin contributes about 70-80% of total cocoon weight where as sericin contributes about 20-30% of total cocoon weight. About 50% of silk waste is generated during silk processing which has proved to be wide application in pharmaceutical and cosmetics applications including its textile application. Sericin is characterized by it's high content of serine (32%). Sericin can be removed by different methods. It has adhesive and gelling in between pH 6-7 make it suitable for preparation of mouth ulcer gel. FT-IR peaks at 1653 cm -1 and 1541 cm-1 for amide I and amide II respectively confirms the α-random coil of sericin and shifting of degradation peak in DSC thermogram confirms insolubility of brown coloured sericin. The sericin gels were prepared using pluronic was found to be sericin concentration dependent, where as sericin concentration independent with carbopol. The rheological and adhesive properties- of sericin are suitable for preparation of sericin gels containing Choline salicylate.
Rats were examined for the effect of consumption of silk protein, sericin on the intestinal absorption of Zn, Fe, Mg and Ca. Male Wistar rats were fed on the diet containing either 23% egg albumin or 20% egg albumin plus 3% sericin for 12 d. Consumption of sericin elevated the apparent absorption of Zn, Fe, Mg and Ca (41%, 41%, 21% and 17%, respectively), but did not affect serum concentrations of these elements. Urinary excretion of the elements was unaffected by dietary sericin. The results suggest that consumption of sericin enhances bioavailability of Zn, Fe, Mg and Ca in rats.
THE silk thread extruded by the lava of the silk moth of commerce (Bombyx mori) consists of two parts: a central core of two filaments of the protein fibre `fibroin', surrounded and cemented together by a layer of protein material called `sericin'.